AVIATION STRUCTURAL MECHANIC E

cockpit canopy should the canopy jettison/fracturing system fail. After ejection, an on-board multi-mode electronic sequencer automatically controls drogue deployment, man/seat separation and parachute deployment. A barostatic release unit provides for partial or total failure of the electronic sequencer and an emergency restraint release (manual override) system provides a further backup in the event of failure of the barostatic release. The seat is ejected by the gas pressure developed within a telescopic catapult when the cartridges are ignited. An underseat rocket motor is fired as the catapult reaches the end of its stroke and sustains the thrust of the catapult to carry the seat to a height sufficient to deploy the parachute. The seat is stabilized and the forward speed retarded by a drogue and bridle system, followed by automatic deployment of the personnel parachute and separation of the occupant from the seat. Timing of all events after rocket motor initiation is controlled by the electronic sequencer, which utilizes altitude and airspeed information to select the correct mode of operation. 2-2 CATAPULT MANIFOLD VALVE LH PITOT (STOWED) PARACHUTE DEPLOYMENT ROCKET 0.75-SECOND DELAY CARTRIDGE ACTUATED INITIATOR LH BALLISTIC MANIFOLD THERMAL BATTERIES HARNESS LAP STRAP(2) SHOULDER HARNESS CONTROL LEVER SEAT HEIGHT ACTUATOR SWITCH LATERAL THRUST MOTOR LEG RESTRAINT LINES CANOPY BREAKER (2) HEADPAD SEAWARS (2) STICKER STRAP (2) LEG RESTRAINT LINE SNUBBER (2) EMERGENCY RESTRAINT RELEASE HANDLE SAFE/ARMED HANDLE EJECTION CONTROL HANDLE SAFETY PIN Figure 2-2.—Forward ejection seat, LH view (SJU-17(V)2/A).

This chapter provides descriptive and operation information for the SJU-17/A series ejection seats. The seats are installed in F/A-18C, F/A-18D, F-14D and T-45A aircraft as detailed below: AIRCRAFT SEAT F/A-18C SJU-17(V)1/A F/A-18D forward SJU-17(V)2/A F/A18D aft SJU-17(V)9/A F-14D forward SJU-17(V)3/A F-14D aft SJU-17(V)4/A T-45A forward SJU-17(V)5/A T-45A aft SJU-17(V)6/A The seven seat variants are essentially similar but incorporate differences to accommodate the seven aircraft installations. For convenience, the description that follows applies to all variants except where noted. Where reference is made to the single seat configuration, the F/A-18C (SJU-17(V)1/A applies, the description applies equally to the aft seat F/A-18D (SJU-17(V)9/A) aircraft installation, except where noted. GENERAL DESCRIPTION LEARNING OBJECTIVE : Identify the components of the NACES seat and their function. Each ejection seat, as installed in the aircraft, comprises five main assemblies (fig. 2-3), which are briefly described in the following paragraphs: • The catapult assembly secures the ejection seat to the aircraft. • The main beam assembly includes the left hand (LH) and right hand (RH) main beams, upper and lower cross-beams, shoulder harness retraction unit, parachute deployment rocket motor, electronic sequencer system, barostatic release unit, drogue deployment catapult, two 2-3 Figure 2-3.—Forward ejection seat, main assemblies (SJU-17(V)2/A).

multipurpose initiators, and two ballistic mani- folds. • The seat bucket assembly includes the underseat rocket motor, leg restraint system, ejection control handle, safe/armed handle, emergency restraint release system, and shoulder harness release fittings. • The parachute assembly consists of the para- chute container and parachute canopy. • The seat survival kit includes the emergency oxygen system, liferaft, survival aids, lap belts, and release fittings. CATAPULT ASSEMBLY The catapult (fig. 2-4) secures the ejection seat to the aircraft structure and provides the initial power for the ejection of the seat. The catapult consists of an outer barrel, an inner telescopic piston, and a catapult manifold valve. The barrel is attached to the aircraft structure and the piston and barrel are engaged at the top end by the top latch plunger installed in the main beam assembly. Explosive charges are contained in an ejection gun initiator JAU-56A and a secondary cartridge. Gas pressure from the seat firing system or the aircraft 2-4 Figure 2-4.—Catapult assembly, forward seat (SJU-17(V)2/A).

command sequencing system operates twin firing pins in the ejection gun initiator to fire the explosive charge. The resultant gas pressure and the heat operate the ballistic latches in the barrel and fire the secondary cartridge as the piston extends. The catapult is water sealed, having seals fitted to the initiator, the secondary cartridge, the breech, and the guide bush. Barrel The barrel is a built-up structure consisting of a light alloy tube with an accurately lapped bore that has permanently attached top and bottom end fittings; a housing towards the bottom end contains the secondary cartridge. Five brackets support two guide rails bolted on diametrically opposite sides of the tube. The bottom end fitting incorporates the lower mounting bracket for attaching the catapult to the aircraft and studs for attachment of the ballistic latches. The upper mounting consists of a bracket clamped on the barrel towards the upper end. It has an interference shoulder on one side to ensure location of the catapult in the correct cockpit (fig. 2-5). An interference arm mounted on one of the guide rail brackets ensures that the correct main beam assembly is installed. A cross-beam secured to the barrel provides an anchorage point for the RH ballistic manifold quick-disconnect lanyard. The top end fitting of the barrel has a square aperture, the barrel latch, through which the plunger of the top latch mechanism fitted on the seat main beam protrudes when the seat is installed on the catapult. A guide bush, fitted in the internal diameter of the top end fitting, is secured by three dowels that are sheared by the head of the piston striking the guide bush. The piston then separates from the barrel and the guide bush remains on the piston. Two ballistic latches are attached to the bottom end fitting by studs and nuts. Each latch comprises a body, internally drilled to form a cylinder and containing a 2-5 Figure 2-5.—Interference devices, forward and aft seats (SJU-17(V)2/A).

spring-loaded piston. When operated during the ejection sequence, gas pressure from within the catapult acts on the latch pistons, overcoming the springs and retaining the multipurpose initiator static lanyard lower end fittings. Piston The piston consists of a light alloy tube, attached to the lower end of a necked end fitted with piston rings to provide a gas seal between the piston and the barrel. At the upper end of the piston is a breech into which is inserted the ejection gun initiator. The breech has a groove machined around its outer diameter into which the plunger of the top latch mechanism on the seat main beams engages when the seat is installed on the catapult. A V-groove in the top of the breech engages a dowel on the seat top cross-beam when the seat is installed in the aircraft. Catapult Manifold Valve The catapult manifold valve (fig. 2-6) is a body with two gas inlet ports, each with a check valve, connected by drillings to a vertical bore. The top of the bore is sealed by a screwed cap and incorporates a spring-loaded sleeve. The end of a key operated spring-loaded plunger protrudes into the bore below the sleeve and a transverse drilling in the valve body breaks through the vertical bore opposite and level with the spring-loaded plunger. The bore of the valve fits over the ejection gun initiator inlet connector, depressing the sleeve against the spring. The valve is held to the inlet connector by the spring-loaded plunger and a key operated quick-release pin that passes through the transverse drilling and engages in a circular groove in the inlet connector. O-ring seals maintain gas integrity between the components. MAIN BEAM ASSEMBLY The main beam assembly is manufactured almost entirely from light alloy and is comprised of two parallel main beams bridged by top and bottom cross-beams and a top latch assembly. A shoulder harness reel is mounted across the front face of the main beams and provides extra rigidity. An electronic sequencer is mounted above the shoulder harness reel. Bolted to the inside face of each main beam are three slippers, which engage in the guide rails on the catapult. Two seat bucket runner guides are attached to the front face of the each main beam and accommodate the top 2-6 Figure 2-6.—Ejection gun initiator JAU-56/A and catapult manifold valve.

and bottom seat bucket slippers. The slippers provide smooth movement of the seat bucket and have threaded studs to attach the seat bucket to the main beam. Friction pads in the studs restrict lateral movement of the seat bucket. Drogue bridle retaining channels are secured to the rear of both main beams. Locating pins for the parachute container hooked brackets are bolted to the upper outside face of each main beam. Interference blocks on the RH beam (forward seat) or LH beam (aft seat) correspond with interference devices on the catapult and the seat bucket to ensure that only the correct assemblies are installed in forward and aft cockpits (fig. 2-5). Top Cross-Beam The top cross-beam receives and positions the top of the catapult and takes the full thrust of the catapult during ejection. Incorporated into the cross-beam is the upper drogue bridle release unit, which attaches the upper leg of the drogue bridle to the seat. The studs securing the RH main beam to the top cross-beam also retain the RH parachute container mounting bracket. Two of the studs securing the LH main beam to the top cross-beam also retain the top latch assembly. A dowel in the top cross-beam is positioned in one of the catapult breech V-grooves when the seat is installed in the aircraft. Bottom Cross-Beam The bottom cross-beam is machined from solid light alloy and retains the main beams at the bottom end. Incorporated into the cross-beam is a gas passage that forms part of the drogue bridle release system. Top Latch Assembly The top latch assembly fitted to the LH main beam secures the seat structure to the catapult. The assembly consists of a housing with a spring-loaded latch plunger, one end of which is shaped to engage the catapult piston. The plunger may be withdrawn using the top latch withdrawal tool (handwheel). Passing through the center of the latch plunger is a spring-loaded indicator plunger. When the ejection seat is fitted to the catapult and the handwheel is removed, the latch plunger passes through the top cross-beam and engages with the barrel latch. The shaped end of the plunger protrudes still further to engage the groove of the catapult piston. Operation of the top latch is shown in figure 2-7. 2-7 Figure 2-7.—Operation of the top latch assembly.

Drogue Deployment Catapult The drogue deployment catapult (fig. 2-8) is mounted outboard of the RH main beam of the ejection seat. Its function is to deploy the stabilization drogue and bridle assembly rapidly without becoming entangled with the seat. The firing of the drogue deployment catapult is controlled by the electronic sequencer to ensure that the seat has cleared the air- craft before the drogue is deployed. The drogue deployment catapult is a cylindrical body with an electrically operated impulse cartridge CCU0101/A, a two-piece telescopic piston assembly, and an enlarged upper end into which is fitted a drogue and canister assembly. DROGUE AND CANISTER ASSEMBLY .— The drogue and canister assembly is comprised of a 57-inch diameter ribbon drogue, pressure-packed into an 8.25-inch-long light alloy cylinder, closed at the 2-8 Figure 2-8.—Drogue deployment catapult.

upper end. Riveted within the lower end of the canister is a shear ring, incorporating a shouldered portion axially separated from the base of the canister by 0.1 inch. At the lower end of the end cap, the same bolt that secures the drogue strop attaches a link assembly. When installed on the ejection seat, the link assembly attaches to the drogue bridle and the canister assembly is retained in the body by a threaded locking ring. At the upper end of the catapult body is riveted a threaded ring onto which the locking ring is screwed when installing the drogue canister. DROGUE AND BRIDLE SYSTEM .—The drogue and bridle assembly (fig. 2-9) is fitted to decelerate and stabilize the ejection seat prior to deployment of the personnel parachute. The drogue bridle is manufactured from 2000-pound Kevlar cord environmentally protected by heat-shrink sleeving and consists of: • two lower bridle legs, 42 inches long, • an upper bridle leg, 43 inches long, and • an extension strop, 37 inches long. The four lengths of drogue bridle are joined at one point by stitching to a 2.5-inch diameter light alloy ring. When installed on the ejection seat, the lower drogue bridle spools are secured in two lower drogue bridle release units built into the multipurpose initiators on the lower main beams. The upper drogue bridle spool is secured in an upper drogue bridle release unit in the top cross-beam and the extension strop spool is attached to the lower end of the link assembly in the drogue deployment catapult. The drogue bridle is retained in channels on the rear face of the seat main beams and folded into a frangible container mounted at the top rear of the main beams. The three bridle release units are activated at the correct time in the ejection sequence by gas pressure from an electrically operated impulse cartridge CCU-100/A installed in a breech in the RH ballistic manifold. The drogue is an Irvin T108-2, 57-inch diameter, 20-degree conical ribbon drogue, attached at the confluence of the rigging lines to a drogue strap. The opposite end of the strap ends in a spool and is attached by a nut and bolt to the link in the drogue deployment catapult. 2-9 Figure 2-9.—Drogue deployed. GUE BRIDLE RELEASE MECHANISM UPPER BRIDLE LEG RING END CAP LINK ASSEMBLY EXTENSION STROP DROGUE LOWER BRIDLE LEGS LOWER DROGUE BRIDLE RELEASE MECHANISMS UPPER DR O

Parachute Deployment Rocket Motor MK 122 MOD 0 The parachute deployment rocket motor (PDRM) (fig. 2-10) is mounted on the LH main beam of the seat. It extracts the personnel parachute from the parachute container and enables the parachute to deploy and develop rapidly without becoming entangled in the seat. The PDRM is a sealed unit and consists of a cylindrical body containing a gas-operated secondary cartridge in a breech at the lower end of a rocket, with an integral gas-operated igniter cartridge in a barrel at the upper end. In a parallel-connected chamber is an electrically initiated primary cartridge. A gas inlet is connected by gas pipe to the harness release system. The rocket incorporates a top cap with four integral rocket nozzles equally spaced around the perimeter. Fitted around the rocket is a sliding stirrup connected to the parachute withdrawal line that is free to slide down the rocket as it leaves the barrel. A retaining screw mounted at an angle in the body bears down on the flanged base of the rocket igniter 2-10 Figure 2-10.—Parachute deployment rocket motor MK 122 MOD 0.

cartridge to retain the rocket in the barrel. The cartridge flange will shear to permit ejection of the rocket during operation. Electronic Sequencing System The electronic sequencing system consists of an electronic sequencer, two thermal batteries, two pitot assemblies, two sequencer start switch assemblies, and the associated electrical wiring. SEQUENCER.—The sequencer (fig. 2-11) is attached across the front of the seat main beams below the parachute assembly. It is connected by pipes to the pitot assemblies and by electrical wiring to the thermal batteries, the sequencer start switches, and the electrically operated cartridges. The sequencer controls drogue deployment and release, personnel parachute deployment, and the man/seat separation. Timings vary with altitude and airspeed. An external test receptacle is provided for periodic testing of the sequencer. THERMAL BATTERIES .—Two thermal bat- teries supplying power for sequencer operation are mounted together in a manifold on the LH main beam. To provide system redundancy, each battery is initiated independently by a manifold-mounted gas-operated firing mechanism. Both firing mech- anisms are initiated by gas pressure from the seat initiator cartridges or the aircraft command sequencing system. 2-11 Figure 2-11.—Electronic sequencer.

2-12 Figure 2-12.—Pitot assembly, right hand. Figure 2-13.—Pitot assembly, right hand, operation.

PITOT ASSEMBLIES .—Two pitot assemblies incorporating deployable pitot heads (fig. 2-12) are mounted on the main beams behind the parachute container. Removable covers prevent entrance of foreign objects during maintenance. The pitot heads are maintained in the stowed position by locking mechanisms that are released during seat ejection, as the seat separates from the catapult by gas pressure from the multipurpose initiator cartridges (fig. 2-13). When deployed, the pitot head assemblies supply dynamic pressure inputs to the electronic sequencer. When the pitot assembly is installed on the seat beam, the inboard static pressure connector connects to a void in the seat beam. The sequencer is installed on the forward face of both pitot assemblies and connects to the dynamic and forward static pressure connectors. START SWITCH ASSEMBLIES .—Two start switch assemblies are incorporated into the multi- purpose initiators. During ejection, the start switches supply a start signal to the sequencer at the correct time in the sequence. Multipurpose Initiators Two initiators multipurpose (IMP) (fig. 2-14) are attached to the lower outer faces of the seat main beams. During the ejection sequence, the IMPs supply gas pressure to operate the barostatic release unit delay mechanism, the underseat rocket motor, the pitot deployment mechanisms, and the internally mounted start switch assemblies. Each IMP comprises a body, machined and drilled to accept a start switch, a static lanyard assembly, a spring-loaded firing pin, and an impulse cartridge. A 2-13 Figure 2-14.—Multipurpose initiator, left hand. IMPULSE CARTRIDGE GAS OUTLET TO BAROSTATIC RELEASE UNIT , PITOT MECHANISMS AND UNDERSEAT ROCKET MOTOR ELECTRICAL CONNECTOR FIRING PIN DIAPHRAGM SHEAR PIN FIRING PIN SPRING DISCONNECT DEVICE COILED LANYARD START SWITCH ELECTRICAL WIRING START SWITCH PLUNGER STATIC LANYARD LOWER END FITTING LOWER DROGUE BRIDLE RELEASE UNIT PISTON

gas passage through the unit body connects the cartridge breech to the lower end of the start switch plunger. The static lanyard assembly comprises a lanyard precoiled into a cylindrical container with special fittings swaged onto each end. The upper end fitting has a wedge-shaped disconnect device, which engages with the lower end of a spring-loaded firing pin positioned below the cartridge. The lower end fitting protrudes through the lower end of the body and is retained by a shear pin. When the seat is installed on a catapult, the protruding lower end fitting fits in one of the catapult-mounted ballistic latches. The start switch is a series of metal sleeves and insulated sections, installed vertically to form an electrical switch assembly. An internal plunger has a short gold-plated section with piston head at its lower end, and is partially sleeved with insulation. A shear pin prevents movement of the plunger before operation. The impulse cartridge is percussion-operated by the firing pin and is screwed into a breech at the upper end of the body. A gas tube machined in the upper part of the cartridge ensures even distribution of gas pressure when the cartridge fires. Barostatic Release Unit The barostatic release unit (BRU) is located on the RH main beam of the seat and contains an impulse cartridge CCU-102/A. The CCU-102/A normally is initiated by the sequencer to supply gas pressure to release the upper and lower harness locks and fire the secondary cartridge in the parachute deployment rocket motor. If the sequencer fails, the BRU cartridge will be fired by mechanical operation of the BRU. The BRU (fig. 2-15) consists of a body containing the impulse cartridge, a barostat assembly, and a 4-second time delay mechanism. BAROSTAT.—The barostat consists of an aneroid capsule housed in the release unit so that a peg attached to the capsule may engage a starwheel in the delay mechanism. At altitudes in excess of the barostat rating (14,000-16,000 feet), the peg engages the starwheel 2-14 Figure 2-15.—Barostatic release unit.

and prevents the delay mechanisms from operating. As altitude decreases, the capsule peg retracts and allows the mechanism to function. IMPULSE CARTRIDGE .—The impulse car- tridge CCU-102/A consists of a cylindrical brass body containing two output charge chambers separated by a central connecting gas gallery. The upper end of the cartridge has two electrical igniters and is electrically initiated by signals from the electronic sequencer—a primary signal to initiate the cartridge and a backup signal through the second connector to provide system redundancy. The lower end is initiated by the delay mechanism firing pin striking the percussion cap. Output charge initiated at either end will crossfire, via the gas gallery, to ignite the output charge in the other chamber. The resultant gas pressure is discharged from the center of the cartridge into an annular groove via gas ports spaced evenly around the central gas gallery. TIME-DELAY MECHANISM.—The time-delay mechanism consists of a spring-loaded rack assembly in mesh with a gear train controlled by an escapement. The gear train consists of a primary spur and gear, a secondary spur and gear, an idler wheel, a release wheel, and a release rocker. The rack assembly consists of a rack end screwed into a slotted end. The two components are secured together with a locking screw. The upper end of the rack end is shaped to form a firing pin. To retain the rack in the cocked position, one face of a ratchet in the bottom housing engages in the slotted end of the rack assembly. Another face of the ratchet engages in a groove in a gas-operated piston installed in a housing attached to the lower part of the unit body. The piston is held in position by a frangible disc. When the RH multipurpose initiator cartridge fires during ejection, gas pressure from the cartridge enters the piston housing and moves the piston upwards, rupturing the frangible disc and allowing the ratchet to pivot clear of the rack assembly’s slotted end. When the altitude is low enough that the barostat is not restraining the mechanism, the rack assembly will rise under the action of its spring, governed by the delay mechanism. After the delay has elapsed, the rack disengages from the gear train and the firing pin rises rapidly to strike the cartridge. If the cartridge has not previously been fired electrically by the sequencer, the gas produced by the cartridge passes out of the BRU to operate the upper and lower harness locks along with the secondary cartridge in the parachute deployment rocket motor. Shoulder Harness Reel The shoulder harness reel (fig. 2-16) is fitted horizontally across the front faces of the main beams and serves as a center cross-beam for the main beams assembly as well as a means of securing the upper harness. It ensures the occupant will be correctly positioned and locked in for ejection. It permits the seat occupant to lean forward and twist around in the seat for maximum visibility, but restrains forward movement in the event of excessive forward deceleration. For normal flight operations the shoulder harness is free to extend and retract as the occupant moves in the ejection seat. The shoulder harness control 2-15 Figure 2-16.—Shoulder harness reel.

lever on the LH side of the seat bucket can be moved to the forward (locked) position, which will permit the harness straps to retract, but prevent them extending. When in the normal unlocked state, the occupant is protected against rapid forward movement under high g-loading by automatic locks, which respond to an excessive rate of strap extraction or aircraft deceleration. On rapid strap extraction or aircraft deceleration the unit mechanism will lock, and when the extraction or deceleration load is released the unit will revert to its normal free state. A g-limiter assembly is installed within the RH end cap. If the seat is subjected to a horizontal deceleration in excess of 0.7g, a weighted ratchet wheel attached to the RH end of the drive screw will prevent strap extraction. Reduction of deceleration below 0.7g and easing of any tension on the straps allows the ratchet spring to reset itself and disengage the ratchet from 2-16 Figure 2-17.—Shoulder harness control system (SJU-17(V)1/A, 2/A and 9/A).

the ratchet wheel, permitting free withdrawal of the straps. SHOULDER HARNESS CONTROL SYS- TEM.—The shoulder harness control lever (fig. 2-17), on the LH side of the bucket, engages in either one of two positions in a quadrant. The lever is connected by links and levers to a torque tube secured to the rear of the seat bucket. A torque bar engaged within the tube allows for vertical adjustment of the seat bucket. The torque bar is secured to the main beam assembly, together with the LH trombone tubes, by a quick-release pin, its upper end engaging in a torque shaft. The shaft is secured to the harness reel and has a fork-end that engages the ratchet wheel. SEAT BUCKET ASSEMBLY The seat bucket is constructed to form a square pan and houses the seat operating controls. The extended back, the bottom and front are made from sheet aluminum alloy. The sides are solid aluminum alloy plates and extend forward to provide thigh protection and support. The bucket is secured to studs incorporated into sliding runners on the seat main beams by four nuts. Interference devices on the rear of the seat bucket and on the main beam assemblies ensure that only the correct seat bucket is installed in forward and aft cockpits (fig. 2-18). Because of aircraft installation requirements, SJU-17(V)1/A, 2/A and 9/A seat bucket assemblies are one inch wider than SJU-17(V)3/A thru 6A assemblies. Detail assemblies are essentially similar between aft seat buckets. The back of the seat bucket contains a rigid molded pad that forms the backrest. It is contoured so at ejection the seat occupant is automatically pulled back by the shoulder harness reel into the correct ejection posture. The backrest is secured by a screw through each side of the seat bucket. A cushion attached to the backrest provides additional comfort. Underseat Rocket Motor MK 123 MOD 0 An underseat rocket motor MK123 MOD 0 (forward seat) or MK 124 MOD 0 (aft seat) installed under the seat bucket is secured to the side plates by nuts and bolts. Differences in mounting bolt sizes 2-17 Figure 2-18.—Interference devices, seat bucket to main beams for the forward and aft seats (SJU-17(V)2/A).

2-18 Figure 2-19.—Underseat rocket motor mounting bolt sizes (SJU-17(V)2/A). Figure 2-20.—Lower harness release mechanism (SJU-17(V)1/A, 2/A and 9/A).

(fig. 2-19) ensure that the correct rocket motor is installed. A gas pipe to the rocket motor firing mechanism is connected to a trombone tube on the LH rear of the seat bucket. The trombone tubes on the rear of the seat bucket connect to ballistic manifolds mounted on the main beams. Connections are a push fit secured by key operated quick-release pins, gas integrity being maintained by O-ring seals. Leg Restraint System The lower harness locks and release mechanism are within the lower rear corners of the seat bucket (fig. 2-20). Halfway up the inner face of the seat bucket sides are sticker clips. The pin puller is mounted at the rear of the seat bucket on the lower right hand side. Two leg restraint line snubbers, each with a leg restraint line, are attached to the front face of the seat bucket. Pulling inboard on the fabric loops attached to the release plungers on the inboard side of each snubber will release them to adjust the leg lines. The leg restraint lines taper plugs are secured in locks positioned on the seat bucket side plates. Seat Height Actuator The seat height actuator (fig. 2-21) adjusts the seat bucket vertically in relation to the seat beams. The assembly consists of a vertical electric motor and housing assembly connected by a transverse gearbox assembly to the upper end of a screwjack housing. 2-19 Figure 2-21.—Seat height actuator (SJU-17(V)3/A and 4/A).

Operating Controls The ejection control handle (figs. 22 and 23) is on the front of the seat bucket, connected by a link and crossbar to the twin sears of the seat initiator located under the seat bucket. The seat initiator is connected by two fixed pipes attached to two trombone tube assemblies, one on either side at the rear of the seat bucket. An upward pull on the ejection handle withdraws the two sears of the seat initiator to simultaneously fire the two-seat initiator impulse cartridges CCU-105/A. SAFE/ARMED Handle The SAFE/ARMED handle is on the RH side of the seat bucket immediately forward of the emergency restraint release handle. A catch in the handle locks it in either the ARMED or SAFE position. The handle is connected to a linkage terminating in a safety plunger, which passes through the link of the ejection control handle when the handle is in the SAFE position and prevents operation of the ejection control handle. In the ARMED position, the visible portion of the handle is colored with yellow and black stripes and engraved ARMED; in the SAFE position the visible portion is colored white and engraved SAFE. An electrical visual SAFE/ARMED indicator is in the cockpit central warning panel and is operated by a micro-switch actuated by the safety plunger. Emergency Restraint Release System The emergency restraint release handle is connected by two link assemblies to the lower harness lock release mechanism and a firing mechanism housed 2-20 Figure 2-22.—Operating controls (SJU-17(V)1/A, 2/A, and 9/A).

in the rear lower RH side of the seat bucket. The handle is locked in the down position by a catch operated by a thumb button at the forward end of the handle; depression of the thumb button allows the handle to be rotated rearward. Handle operation when the seat is installed is restricted by the pin puller so it releases only the lower torso restraint and leg restraint lines to permit emergency ground egress. On ejection, the pin puller is automatically disengaged from the handle-operating link. Operation of the emergency restraint release handle simultaneously operates the SAFE/ARMED handle to the SAFE position. In the unlikely event of automatic sequence failure, operation of the emergency restraint release handle subsequent to ejection will fire a cartridge to operate the upper and lower harness locks and the parachute deployment rocket motor. Shoulder Harness Control System The shoulder harness control lever is attached to the LH side of the seat bucket and is connected by a linkage, torque tube, and rod to the shoulder harness reel. When the lever is in the forward position the shoulder harness reel is locked, preventing all forward movement of the seat occupant. When moved to the rear position, the seat occupant is free to move forward and aft at will; should the seat occupant move forward rapidly, however, the shoulder harness reel will lock until the load on the webbing straps is eased. To operate the control, the lever is moved along a quadrant until a spring-loaded plunger engages in either one of two positions in the quadrant backplate. The lever will automatically engage where selected. 2-21 Figure 2-23.—Operating controls (SJU-17(V)3/A and 4/A).

On SJU-17(V) seats 1/A, 2/A, 5/A, 6/A, and 9/A the seat height actuator switch is situated immediately forward of the shoulder harness control lever on the LH side of the seat bucket. On SJU-17(V) 3/A and 4/A the switch is situated immediately aft of the emergency restraint release handle on the RH side of the seat bucket. Forward movement of the toggle switch lowers the seat bucket, and aft movement raises the seat bucket. When released, the toggle assumes the center OFF position. PARACHUTE ASSEMBLY The parachute assembly (fig. 2-24) is a 21-foot-diameter GQ Type 5000 personnel parachute packed into a rigid container and connected to the parachute risers. The parachute risers incorporate seawater-activated release switches (SEAW ARS) for attachment to the upper torso harness. These switches will automatically release the ejectee from the parachute following descent into seawater. The parachute assembly is attached to the upper forward face of the ejection seat main beams. Parachute Container The parachute container is made of light alloy, with canopy penetrators fitted to each upper outboard side. The penetrators on the forward seat are longer than those on the aft seat. The SJU-17(V)9/A parachute, installed in the aft cockpit of the TF-18/A, also has a single penetrator installed centrally aft on the container lid. Brackets, integral with the rear of the canopy penetrators, are bolted to brackets on the main beams. A shaped headpad is attached to the front face of the container for head placement during ejection. Hook and pile fasteners are fitted to the front face of the headpad to position the parachute risers. A rigid top cover closes 2-22 Figure 2-24.—Parachute assembly (SJU-17(V)2/A and 5/A).

the container, with a single lug on the RH side and two lugs on the LH side. The RH lug is positioned in a slot in the RH canopy mechanism incorporated into the LH canopy penetrator. The LH lugs deform during parachute extraction, releasing the cover to permit rapid parachute deployment. A fairing on the LH rear corner of the cover protects the parachute withdrawal line where it exits the container. The lid and withdrawal are fitted with seals to prevent the entry of moisture. Parachute Canopy The parachute canopy is comprised of 20 gore and shroud lines, and incorporates water pockets and steering facilities. The canopy is packed peak first into a deployment bag, the closed end of which is attached via a withdrawal line to the stirrup on the parachute deployment rocket. During the ejection sequence the parachute deployment rocket motor fires, extending the withdrawal line that withdraws the parachute in its bag. The parachute canopy emerges from the bag, perimeter first, followed progressively by the remainder of the canopy. The extractor rocket and bag clear the area. At high airspeeds the crown section inflates and surplus air is vented through a circumferential netted slot and the peak vent. The lower section remains closed until airspeed is reduced to safe opening speed, when the lower portion inflates normally. SEAT SURVIV AL KIT The survival kit (figs. 2-25 and 2-26) fits into the seat bucket and consists of a rigid contoured platform to which is attached an emergency oxygen system and a 2-23 Figure 2-25.—Seat survival kit, top view. Figure 2-26.—Seat survival kit, bottom view.

fabric survival package. A cushion on top of the platform provides a firm and comfortable seat for the occupant. There are three different survival kit configurations for the various NACES platforms: KIT AIRCRAFT CONFIGURATION SKU-7/A F-14D SJU-17(V)3/A and 4/A SKU-10/A F/A-18C/D SJU-17(V)1/A, 2/A and 9/A SKU-11/A T-45A SJU-17(V)5/A and 6/A Basic differences between survival kits are as follows: KIT CHARACTERISTICS SKU-7/A Narrow kit 50-cubic-inch oxygen cylinder (100 liters) Used in conjunction with Personnel Services Disconnect installed on the LH SKU-10/A Wide kit 100 cubic inch oxygen cylinder (200 liters) SKU-11/A Narrow kit 100 cubic inch oxygen cylinder (200 liters) Rigid Platform The rigid platform forms a hard protective cover to the survival package and oxygen system and is retained in position in the seat bucket by brackets at the front and lugs at the rear to secure the lower harness locks. Attached to the lugs are two adjustable lap belts with integral quick-release fittings. Emergency Oxygen System An emergency oxygen cylinder, a pressure reducer, and associated plumbing are mounted on the underside of the platform. A green manual operating handle is mounted on the LH side of the platform and a cylinder quantity gauge is on the inside of the face of the left-hand thigh support. The emergency oxygen is automatically activated during ejection by a lanyard connected to the cockpit floor. An oxygen/communications hose is connected to unions on the LH rear top of the rigid platform and provides connections between the seat occupant, aircraft, and survival kit systems. URT-33/A Radio Locator Beacon The URT-33/A radio locator beacon is located in a cut-out in the left thigh support. The beacon is actuated during ejection by a lanyard connected to a common anchorage point with the emergency oxygen lanyard. Survival Package The survival package is held on the underside of the rigid platform by five fabric straps and a double cone and pin release system. The package accommodates a liferaft and the survival aids. Yellow manual deployment handles mounted on the kit enable the occupant to deploy the package onto a lowering line after man/seat separation. The liferaft inflates auto- matically on survival package deployment. SAFE/ARMED Indicator Switch The SAFE/ARMED indicator switch is located on the front of the seat bucket, left of the ejection control handle linkage. The SAFE/ARMED indicator switch is made up of a switch, plunger, and a wiring harness that mate to the electrical connector housing in the seat bucket. The ejection control handle mechanical safety lock actuates the plunger on the SAFE/ARMED indicator switch when the SAFE/ARMED handle is up in the SAFE position. The SAFE/ARMED handle is set to the ARMED position (seat armed) when the aircraft is ready for flight. When in the ARMED position, the visible portion of the handle is colored with yellow and black markings and placarded as ARMED. When in the SAFE position, the visible portion is colored white and placarded as SAFE. Q2-1. List the five main assemblies of the NACES. Q2-2. What is the purpose of the drogue and bridle system? Q2-3. What component supplies dynamic pressure inputs to the electronic sequencer? Q2-4. The SAFE/ARMED handle displays what color when in the ARMED position? Q2-5. An F/A-18C aircraft uses what type of seat survival kit? EJECTION LEARNING OBJECTIVE : Identify the ejection sequence and the different modes of operation. 2-24

When the ejection control handle is pulled, the sears are withdrawn from the seat initiator firing mechanisms (fig. 2-27) and the two impulse cartridges are fired, catapulting the seat free of the aircraft and starting the sequencer modes for seat/occupant separation and parachute deploy- ment. EJECTION SEQUENCE On firing of the impulse cartridges, gas from the RH and LH cartridges is routed as described. RH Initiator Cartridge Gas from the RH cartridge is piped as follows: 1. To the pin puller (fig. 2-28), which withdraws a piston from engagement in the lower operating 2-25 Figure 2-28.—Emergency restraint release system (SJU-17(V)1/A, 2/A, and 9/A). GAS PIPE FROM SEAT INITIATOR PIN PULLER HANDLE FIRING MECHANISM LEG RESTRAINT LINE OPERATING LINK SPRING-LOADED PLUNGER GUIDE BRACKET PLUNGER PISTON CROSS-SHAFTGAS PASSAGE PISTON GROOVE SLOT OPERATING TANK RS IMPULSE CARTRIDGE BODY LH FIRING MECHANISM RH FIRING MECHANISM IMPULSE CARTRIDGE CCU-105/A SEARS Figure 2-27.—Seat initiator. CONNECTO

link of the emergency restraint release mech- anism. 2. To the inboard connector of the command sequencing system quick-disconnect on the RH ballistic manifold (fig. 2-29) to operate the command sequencing system. 3. SJU-17(V)1/A, 6/A and 9/A only. To the cartridge actuated initiator on the RH ballistic manifold. Gas from the initiator passes to the RH inlet of the catapult manifold to initiate the catapult. 4. To the breech of the shoulder harness reel where it fires the impulse cartridge to pull the seat occupant into the correct position for ejection. 5. To the thermal batteries. 6. SJU-17(V)2/A thru 5/A only. To the cartridge actuated initiator on the LH ballistic manifold (fig. 2-30). Gas from the initiator passes to the LH inlet of the catapult manifold valve to initiate the catapult. 7. All configurations. If the seat is command ejected (i.e., the ejection control handle on the other seat has been pulled) gas from the command sequencing system enters the RH seat initiating system through the inboard connector of the command sequencing quick-disconnect on the RH ballistic manifold. On SJU-17(V)2/A thru 5/A, gas pressure also enters the outboard connector on the command sequencing quick-disconnect and is passed to the catapult manifold valve to initiate the catapult. This gas pressure is also piped, via a check valve, to the shoulder harness reel and thermal batteries. LH Initiator Cartridge Gas from the LH cartridge is piped as follows: 1. To the thermal batteries. 2-26 Figure 2-29. RH ballistic manifold (SJU-17(V)2/A thru 5/A).

2. SJU-17(V)1/A thru 5/A and 9/A only. To the cartridge actuated initiator on the LH ballistic manifold. Gas from the initiator passes to the LH inlet of the catapult manifold valve to initiate the catapult. 3. SJU-17(V)6/A only. To the LH inlet of the catapult manifold valve to initiate the catapult. Gas from the cartridge actuated initiator(s) or the command sequencing system is piped to the ejection gun initiator via the manifold valve. Gas pressure developed by the ejection gun initiator passes down the catapult to operate the ballistic latches, retaining the IMP lanyard end fittings. As the pressure increases within the catapult, the catapult piston rises, releases the top latch, and begins to move the seat upwards. Further movement of the piston uncovers the catapult secondary cartridge, which is fired by the heat and pressure of the ejection gun initiator gas. Staggered firing of the catapult cartridges provides a relatively even increase in gas pressure during catapult stroke to eliminate excessive g-forces during ejection. As the seat ascends the guide rails: 1. The IMP lanyards begin to withdraw. 2. Personnel services between the seat and aircraft are disconnected. 3 . The command sequencing system quick-disconnect is disconnected. 4. The emergency oxygen supply is initiated. 5. The URT-33/A beacon is activated. 6. The leg restraint lines are drawn through the snubbers and restrain the occupant’s legs to the front of the seat bucket. When the leg restraint lines become taut, the special break rings in the leg lines fail and the lines are freed from the aircraft. The lines being restrained by the snubbers prevent forward movement of the legs. Near the end of the catapult stroke, the IMP lanyards become taut and operate the firing mechanisms. Gas pressure from the IMP cartridges passes: 1. To the start switch plungers. Closure of the start switches commences sequencer timing. 2. To the barostatic release unit release piston (from the RH IMP only). 2-27 Figure 2-30. LH ballistic manifold (SJU-17(V)2/A thru 5/A).

3. To the pitot mechanisms to deploy the pitot heads. 4. Via the LH ballistic manifold and trombone tube to the underseat rocket motor (fig. 2-31). The rocket motor ignites, sustaining the thrust of the catapult to carry the seat clear of the aircraft. Sequencer Modes Figures 2-32 and 2-33 identify the various modes. Electronic sequencer timing (table 2-1) commences 2-28 Figure 2-31.—Underseat rocket motor MK 123 MOD 0 (SJU-17(V)2/A, 3/A, and 5/A). Figure 2-32.—Ejection modes.

2-29 5 a. PARACHUTE INFLATES b. PARACHUTE DEPLOYMENT ROCKET CLEARS AREA c. SURVIVAL KIT RETAINED 6 DESCENT ON PARACHUTE 4 a. DROGUE RELEASES AT BAROSTAT ALTITUDE b. PARACHUTE DEPLOYMENT ROCKET FIRES c. HARNESS TO SEAT CONNECTIONS RELEASE 2 2 3 DROGUE STABILIZING AND RETARDING SEAT 1 1 a. EJECTION CONTROL HANDLE PULLED b. REEL RETRACTS SHOULDER STRAPS c. CANOPY JETTISONS/FRACTURES d. THERMAL BATTERIES ACTIVATE e. CATAPULT INITIATES f. BALLISTIC LATCHES CLOSE 2 a. EMERGENCY OXYGEN ACTIVATES b. RADIO BEACON ACTIVATES c. SERVICES DISCONNECT d. LEGS RESTRAINED e. PITOT HEADS DEPLOY f. START SWITCHES CLOSE g. U/SEAT ROCKET MOTOR FIRES h. DROGUE DEPLOYMENT CATAPULT FIRES 3 a. DROGUE DEPLOYS b. DROGUE RELEASES c. PARACHUTE DEPLOYMENT ROCKET FIRES 2 2 1 MODE 5 MODE 1 MODES 2,3 AND 4 1 Figure 2-33.—Ejection sequence (sheet 1 of 2).

2-30 3 DROGUE STABILIZING AND RETARDING SEAT 4 PARACHUTE DEPLOYMENT ROCKET FIRES 6 DESCENT ON PARACHUTE 5 a. HARNESS TO SEAT CONNECTIONS RELEASE b. PARACHUTE INFLATES UNDER CONTROL OF CROWN BRIDLE c. PARACHUTE DEPLOYMENT ROCKET CLEARS AREA d. SEAT SEPARATES AND FALLS CLEAR e. SURVIVAL KIT RETAINED 5 a. HARNESS TO SEAT CONNECTIONS RELEASE b. PARACHUTE INFLATES c. PARACHUTE DEPLOYMENT ROCKET CLEARS AREA d. SEAT SEPARATES AND FALLS CLEAR e. SURVIVAL KIT RETAINED 4 PARACHUTE DEPLOYMENT ROCKET FIRES 6 DESCENT ON PARACHUTE Figure 2-33.—Ejection sequence (sheet 2 of 2).

when the start switches close. Mode selection is dependent on altitude and airspeed parameters. SEQUENCER MODES When the ejection seat is fired, two onboard thermal batteries are immediately energized, supplying usable electrical power to the sequencer after just 100 milliseconds, with the seat having traveled about 5 inches up the ejection catapult. The sequencer microprocessors then run through an initialization routine and by 120 milliseconds the sequencer is ready and waiting to perform. As the seat rises from the cockpit, two steel cables (approximately 42 inches) are pulled from the multipurpose initiators, actuating two pyrotechnic cartridges. The gas generated by these two cartridges is piped around the seat to perform the following functions: • Initiate the underseat rocket motor • Deploy the pitot tubes from the sides of the seat headbox • Close two electrical switches (sequencer start switches) The sequencer responds to the closure of either start switch by changing to the ejection mode. The switch starts an electronic clock and all subsequent events are timed from this point. In the absence of a 2-31 Altitude (ft): 0-8K 8K-18K 18+ KEAS: 0-300 300-500 500-600 ALL ALL MODE: 12 3 4 5 1. Gas pressure from seat initiator cartridges, delay cartridge, or command sequencing system initiates catapult and thermal batteries. 0.00 0.00 0.00 0.00 0.00 2. Start switches close after 32 inches of seat travel. 0.18 0.18 0.18 0.18 0.18 3. Sequencer supplies dual pulse to fire drogue deployment catapult. 0.22 0.22 0.22 0.22 0.22 4. Sequencer supplies dual pulse to fire drogue bridle release cartridge and release drogue bridle. 0.32 —— — — 5. Sequencer supplies dual pulse to fire parachute deployment rocket. 0.45 1.10 1.30 2.90 4.80 +t 6. Sequencer supplies dual pulse to fire drogue bridle release cartridge and release drogue bridle. — .125 1.45 3.05 4.95 +t 7. Sequencer supplies dual pulse to fire barostatic release unit cartridge and release harness locks. 0.65 1.30 1.50 3.10 5.00 +t 8. Sequencer supplies dual pulse to fire barostatic release unit cartridge (backup). 0.66 1.31 1.51 3.11 5.01 +t NOTES TO TABLE 2-1 1. All times are referenced to seat catapult initiation. To obtain times referenced to sequencer start switches, subtract 0.18 second. 2. Mode selection environmental sensing takes place between 0.245 second and 0.305 second (8 microprocessor cycles). 3. In mode 5 operation, altitude sensing recommences at 4.80 seconds, continuing until the seat falls to 18,000 ft. (t)=time interval between 4.80 seconds and falling to 18,000 ft. Table 2-1.—Sequencer Timings

start switch signal, the sequencer will simply continue in thewait mode. This mode is a safety feature designed to ensure that the drogue and parachute can only be deployed after the seat has physically separated from the aircraft. The ignition of the underseat rocket motor is timed to occur just as the seat separates from the ejection catapult, at about 200 milliseconds, so as to maintain a uniform vertical acceleration profile on the seat and occupant. The motor has a burn time of 250 milliseconds. Once the sequencer is switched into the ejection mode, its first action is to electrically fire the drogue deployment canister, which occurs at precisely 40 milliseconds after the start switch (approximately 220 milliseconds from seat initiation), while the seat rocket motor is burning. This happens regardless of the speed and altitude conditions. The sequencer then enters its most crucial period, when it will sense the seat airspeed and altitude and choose the appropriate timings from a set of five available sequences. This occurs during a 60 millisecond environmental sensing time window that starts just after the drogue canister is fired, and is completed before the drogue is fully deployed and pulling on the back of the seat. The sequencer measures the speed and altitude from the information it receives from three types of sensor: pitot pressure, base pres- sure, and accelerometer. Several samples of each parameter are taken during the environmental window. These are used to determine the ejection conditions. The sequencer then selects the appropriate times for the remaining events, known as mode selection, and completes the sequence accordingly. ALL MODES .—The start switches close after approximately 32 inches of the seat travel, and after 0.04 seconds the drogue deploys onto the bridle to stabilize and decelerate the seat. MODE 1: LOW SPEED – LOW ALTITUDE.— The drogue bridle is released, the parachute deploy- ment motor fires to deploy the personnel parachute and the harness release system operates to free the occupant from the seat. The occupant is momentarily held in the seat bucket by the sticker straps. MODES 2, 3 and 4: MEDIUM and HIGH SPEEDS/LOW ALTITUDE and ALL SPEEDS/MEDIUM ALTITUDE .—The drogue bridle is released, the parachute deployment rocket fires to deploy the parachute, the drogue bridle is released, and the harness release system operates to free the occupant from the seat. The occupant is momentarily held in the seat bucket by the sticker straps. MODE 5: ALL SPEEDS/HIGH ALTITUDE.— The drogue bridle remains connected until the seat has descended to 18,000 feet. This arrangement prevents prolonged exposure to low temperature and un- substantial air. This enables the occupant to ride down in the seat supplied with emergency oxygen to a more tolerable altitude. When the seat has descended to 18,000 feet, the parachute deployment rocket motor fires to deploy the personnel parachute, the drogue bridle is released and the harness release system operates to free the occupant from the seat. The occupant is momentarily held in the seat bucket by the sticker straps. ALL MODES.—The personnel parachute, when developed, lifts the occupant and survival kit from the seat, pulling the sticker straps from their clips. This arrangement ensures that there is no possibility of collision between the seat and occupant after separation. Q2-6. For all configurations, if the seat is command ejected, gas from the command sequencing system enters through what initiating system? Q2-7. During ejection, what distance does the seat have to travel before the drogue chute deploys? Q2-8. MODE 1 occurs at what speed and altitude? 2-32

CHAPTER 2 ANSWERS TO REVIEW QUESTIONS A2-1. The catapult, main beam assembly, seat bucket assembly, parachute assembly, and seat survival kit A2-2. Used to decelerate and stabilize the ejection seat prior to deployment of the personnel parachute A2-3. Pitot assemblies A2-4. Yellow and black stripes A2-5. SKU-10/A A2-6. RH seat initiating system A2-7. 32 inches A2-8. Low speed—low altitude 2-33

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CHAPTER 3 CANOPY SYSTEMS The canopy on modern high-performance aircraft serves several purposes. It protects the crew, provides enhanced visibility, and serves as an avenue of escape in case of emergency. The canopy system includes the canopy itself, plus all the components used in opening and closing the canopy for normal entrance and exit, as well as those used in jettisoning the canopy during an emergency. Inspection and maintenance of canopy actuating systems are important responsibilities of the AME. Aircraft manufacturers have designed various methods of actuating the canopy. Normal opening and closing may be done pneumatically (compressed air), electrically, manually, or hydraulically. Emergency opening (jettisoning) is done pneumatically or explosively. In most instances, more than one method is provided for normal opening and closing of the canopy; thus, if one system fails, the other may be used. The same holds true for jettisoning the canopy. This chapter will discuss the pneumatic canopy system on the F-14 and the frangible escape canopy system on the S-3 aircraft. DESCRIPTION LEARNING OBJECTIVE : Describe the F-14 pneumatic canopy system. The pneumatic canopy system provides normal opening and closing of the canopy in the F-14 aircraft. The system is controlled with the canopy control handle at each crew station or with the external canopy control handle on the fuselage left side. Pneumatic pressure from externally serviced reservoirs supplies the power for the different modes of canopy operation. The canopy also can be manually opened and closed. A reference mark is painted on the fuselage and canopy. When the canopy is closed and locked, the marks are aligned. Q3-1. What provides the power for the different modes of canopy operation? Q3-2. What is painted on the canopy to provide a visual display of being closed and locked? COMPONENTS LEARNING OBJECTIVE: Identify compo- nents of the pneumatic canopy system and their function. This section will cover the canopy and following components: canopy hydraulic actuator, canopy-lock pneumatic actuator, lock actuator restrictor, canopy pneumatic timer, canopy pneumatic control module, canopy pneumatic reservoir, pneumatic servicing charging module, canopy switch, auxiliary pneumatic reservoir, unlock shuttle valve, and the lock actuator check valve. CANOPY The canopy is a transparent enclosure for the cockpit; it consists of two acrylic panels in a metal frame. During normal operation, a pneumatically controlled canopy hydraulic actuator opens and closes the canopy. A canopy-lock pneumatic actuator moves it to the locked or unlocked position. It is locked in the closed position by 14 locking hooks that engage latches on the cockpit sill. An inflatable rubber seal in the canopy is closed and locked. Three rearview mirrors are mounted on the pilot forward canopy frame; one, on the naval flight officer (NFO) forward canopy frame. The canopy can be jettisoned in an emergency on the ground and during the ejection sequence. Figure 3-1 displays the canopy pneumatic systems component locations. CANOPY HYDRAULIC ACTUATOR The canopy hydraulic actuator (fig. 3-1, Item D) opens and closes the canopy. It consists of a double-acting hydraulic cylinder, two transfer cylinders, and two hydraulic control modules. The transfer cylinders transfer pneumatic pressure from the canopy pneumatic control module to hydraulic power. The hydraulic control modules contain pneumatically actuated shutoff valves that hydraulically lock the canopy actuator in any position. When the canopy pneumatic control module is in the neutral position, flow regulators control actuator speed by permitting free flow of hydraulic fluid to the actuator and restricted flow from the actuator, and thermal relief valves relieve pressure from the double-acting cylinder to the transfer 3-1

cylinders. The canopy hydraulic actuator is accessible from the NFO station when the canopy is opened and the NFO ejection seat is removed. CANOPY-LOCK PNUEMATIC ACTUATOR The canopy-lock pneumatic actuator (fig. 3-1, Item G) locks and unlocks the canopy. It operates with nitrogen pressure from the canopy pneumatic control module and the canopy pneumatic timer. The actuator moves the canopy forward or aft the RETR (locked) or EXT (unlocked) position, respectively. When the actuator piston reaches its full EXT (unlock) travel limit, the timer check valve permits pneumatic-pressure flow from the canopy hydraulic actuator. While the canopy closes, the timer check valve vents pneumatic pressure from the canopy hydraulic actuator through the canopy pneumatic control module. When the canopy-lock pneumatic actuator piston moves toward the RETR (locked) position, the timer check valve reseats. LOCK ACTUATOR RESTRICTOR The lock actuator restrictors (fig. 3-1, Item G) regulate the speed of the canopy-lock pneumatic actuator during locking and unlocking of the canopy. CANOPY PNEUMATIC TIMER The canopy pneumatic timer (fig. 3-1, Item E) permits pneumatic pressure flow from the canopy pneumatic control module to the lock side of the canopy-lock pneumatic actuator and vents or pressurizes the canopy hydraulic actuator shutoff valves. The last closing motion of the canopy actuates the timer. 3-2 Figure 3-1.—Canopy pneumatic system components. 01 AUXILIARY UNLOCK PNEUMATIC RELEASE VALVE AND UNLOCK SHUTTLE VALVE ACCESS CANOPY-LOCK PNEUMATIC ACTUATOR AND LOCK ACTUATOR RESTRICTOR AUXILIARY PNEUMATIC RESERVOIR FILLER MANIFOLD CANOPY SWITCH ACCESS AUXILIARY PRESSURE REDUCER AND AUXILIARY PNEUMATIC RESERVOIR AND RELIEF VALVE CANOPY CANOPY PNEUMATIC CONTROL MODULE (NFO STATION) LOCK ACTUATOR CHECK VALVE CANOPY PNEUMATIC TIMER CANOPY PNEUMATIC RESERVOIR AND RESERVOIR CHECK AND RELIEF VALVES LOCK ACTUATOR RESTRICTOR PNEUMATIC SERVICING CHARGING MODULE AND FILLER VALVE CANOPY PNEUMATIC CONTROL MODULE CANOPY HYDRAULIC ACTUATOR G H, J H D C F B AMEf0 A E D D G G 3

CANOPY PNEUMATIC CONTROL MODULE The canopy pneumatic control module (fig. 3-1, Item C) regulates pressure from the canopy pneumatic reservoir and directs it to the canopy pneumatic timer, the timer check valve, canopy hydraulic actuator, and the canopy-lock pneumatic actuator. The module contains a filter, a restrictor, two pressure reducers, two relief valves, a low-pressure sensor, and control valves. If canopy pneumatic reservoir pressure drops below 225 pounds per square inch (psi), the low-pressure sensor causes the module valves to lock the remaining pressure in the canopy hydraulic actuator to counterbalance the weight of the canopy. Canopy unlocking is done by the auxiliary unlock mode. CANOPY PNEUMATIC RESERVOIR The canopy pneumatic reservoir (fig. 3-1, Item A) stores high-pressure dry nitrogen for operation of the canopy pneumatic system. The reservoir is serviced to 3,000 psi; it has a 225-cubic inch capacity. Servicing is done through the pneumatic servicing charging module, which is remote from the reservoir. The reservoir relief valve (fig. 3-1, Item A), on the canopy pneumatic reservoir, prevents overpressuriza- tion of the reservoir. The valve opens at 4,500 psi and reseats at 4,100 psi. PNEUMATIC SERVICING CHARGING MODULE The pneumatic servicing charging module contains a filler valve, a filter, two check valves, and two pressure gauges. The filler valve enables filling both the canopy pneumatic reservoir and the emergency landing gear reservoir from a single point. The check valve prevents reverse flow when one reservoir has a lower pressure than the other. CANOPY SWITCH The canopy switch (fig. 3-1, Item G) is actuated by the canopy locking mechanism lock pin. The switch closes when the canopy unlocks. This completes a circuit to the canopy caution indicator lights on the pilot and NFO caution advisory indicators. When the canopy locks, the switch opens. AUXILIARY PNEUMATIC RESERVOIR The auxiliary pneumatic reservoir (fig. 3-1, Item H) has a 14.6-cubic-inch capacity. It stores high-pressure dry nitrogen for unlocking the canopy in the auxiliary mode. The reservoir is serviced, through the filler manifold, to 3,000 psi. Auxiliary Pneumatic Reservoir Filler Manifold The auxiliary pneumatic reservoir filler manifold (fig. 3-1, Item J) is connected to the auxiliary pneumatic reservoir. It consists of a nitrogen filler valve and pressure gauge. Auxiliary Pneumatic Reservoir Relief Valve The auxiliary pneumatic reservoir relief valve (fig. 3-1, Item H), adjacent to the auxiliary pneumatic reservoir, is connected to the reserve outlet port. It is a spring-loaded poppet valve that prevents over- pressurization of the auxiliary pneumatic reservoir. Valve cracking pressure is 4,500 pounds per square inch gauge (psig); full flow occurs at 5,100 psig. The valve reseats when the auxiliary pneumatic pressure drops to 4,100 psig. Auxiliary Pressure Reducer The auxiliary pressure reducer (fig. 3-1, Item H) is downstream of the auxiliary pneumatic reservoir. It reduces pneumatic pressure to 760 ± 30 psi applied to the auxiliary unlock pneumatic release valve. Auxiliary Unlock Pneumatic Release Valve The auxiliary unlock pneumatic release valve (fig. 3-1, Item G) is a lever-operated shutoff valve that is connected by a cable and pulley assembly to the canopy control handle in the pilot and NFO stations. It is a two-position valve operated by a cam mechanism, which maintains it in the open position. An internal vent releases pneumatic pressure when the auxiliary mode is not selected. When the auxiliary mode is selected to unlock the canopy, the vent port is blocked to permit pneumatic pressure application to unlock shuttle valve. After each auxiliary mode operation, the cam must be reset manually to return the system to normal. UNLOCK SHUTTLE V ALVE The unlock shuttle valve (fig. 3-1, Item G) is a three-port, pressure-operated valve. An internal spool is shuttled by pneumatic pressure at either end of the valve housing to block one of the two end inlet ports. When the canopy control handle is moved to the OPEN 3-3

position, pneumatic pressure flows from the canopy pneumatic control module, through the shuttle valve and the unlock actuator restrictor, to the unlock side of the canopy-lock pneumatic actuator. In the auxiliary mode (AUX OPEN), auxiliary pneumatic pressure shuttles the valve spool in the opposite direction to route auxiliary pneumatic flow from the auxiliary unlock release valve to the unlock end of the canopy-unlock release valve to the unlock end of the canopy-lock pneumatic actuator. LOCK ACTUATOR CHECK V ALVE The lock actuator check valve (fig. 3-1, Item G) prevents nitrogen from venting overboard during the canopy normal closing and holding modes. Q3-3. The canopy is made of what type of material? Q3-4. How is the canopy actuator locked? Q3-5. Describe the function of the lock actuator restrictor. Q3-6. At what pressure does the low-pressure sensor cause the module valves to lock the remaining pressure in the canopy hydraulic actuator? Q3-7. The canopy pneumatic reservoir is (a) what cubic capacity and (b) serviced to what psi? Q3-8. What item prevents overpressurization of the reservoir? Q3-9. Where is the auxiliary pressure reducer? Q3-10. What type of valve is the unlock shuttle valve? OPERATION LEARNING OBJECTIVE : Describe the modes of operation of the pneumatic canopy system. The canopy pneumatic system is operated by setting any one of the three canopy control handles, which positions valves within the pneumatic control module to route pneumatic pressure to or from the system. The modes of operation that can be selected are: normal opening mode, holding mode, normal closing mode, boost closing mode, and auxiliary opening mode. The function of all three control handles is the same; the following modes describe the operation using the pilot handle. NORMAL OPENING MODE Setting the pilot canopy control handle to OPEN pulls the lock pin and positions valves no. 1, 2, and 6 within the control module. This directs nitrogen (325 psi), through the C1 and C3 ports of the module, to the timer check valve and unlock port of the canopy lock pneumatic actuator. Simultaneously, the shutoff valves in the open and close modules of the canopy hydraulic actuator are vented to atmosphere through the C5 port of the actuator, through the canopy pneumatic timer, and through valve no. 3 in the control module. The lock port of the canopy lock pneumatic actuator is vented overboard through the pneumatic timer; the piston of the actuator extends and, by means of torque tube, cranks, and links, moves the canopy aft to unlock it from the still locks. When the extending piston reaches the end of its stroke, ball locks engage to hold it in that position. The extended piston also actuates the timer check valve, which directs the 325-psi nitrogen to the C1 port of the canopy hydraulic actuator. The nitrogen that enters the hydraulic actuator acts against the piston of the open transfer cylinder. This pressure, acting against the piston, causes the hydraulic fluid on the opposite side of the piston to extend the actuator. The extending actuator rotates the canopy on the aft hinge to open the canopy. As the actuator extends, fluid displaced from the close side of the actuator acts against the piston of the close transfer cylinder. The nitrogen on the opposite side of this piston is vented overboard through the C2 port of the hydraulic actuator and through valve no. 4 of the control module. Pulling the lock pin at the beginning of the opening cycle closes the canopy switch, which provides 28 volts from the essential dc no. 2 bus, through the CAN/LAD CAUTION/EJECT CMD IND circuit breaker, to the canopy caution indicator light on the pilot and NFO CAUTION ADVISORY indicators. HOLDING MODE The HOLD position stops canopy motion at any desired opening. Valve no. 3 in the control module directs 325-psi nitrogen through the C5 port of the module, through the pneumatic timer to the C5 port of the hydraulic actuator. The nitrogen that enters the C5 port closes the shutoff valves in the open and close modules. The closed shutoff valves trap hydraulic fluid on the open and close side of the actuator piston, stopping piston travel. 3-4

NORMAL CLOSING MODE Setting the control handle to CLOSE positions valves no. 1, 2, 4, and 5 in the control module to vent both transfer cylinders and the unlock port of the canopy-lock pneumatic actuator overboard. The weight of the canopy closes it; pneumatic power is not required. The closing time, approximately 10 seconds from the fully open position, is controlled by the flow regulators in the open and close control modules of the hydraulic actuator, unlatching the ball locks. The actuator piston retracts and, by means of a torque tube, cranks, and links, moves the canopy forward to engage the canopy hooks in the sill locks. With the canopy in its fully forward position, the lock pin engages and prevents aft transition of the canopy. The final motion of the lock pin opens the canopy switch, breaking the circuit to the canopy caution indicator light on the CAUTION ADVISORY indicators; the lights go off. BOOST CLOSING MODE To close the canopy under high-headwind conditions, the canopy control handle must be moved to BOOST. Valve no. 4, in the control module, is positioned to direct 790 psi nitrogen through the C2 port of the canopy hydraulic actuator to the close transfer cylinder, and through the lock actuator check valve to the P5 port of the pneumatic timer. This nitrogen, acting against the transfer cylinder piston, causes the hydraulic fluid on the opposite side of the piston to retract the actuator, closing the canopy. The final closing motion of the canopy actuates the pneumatic timer, directing 790 psi nitrogen to the lock port of the canopy lock pneumatic actuator; this unlatches the ball locks. The system functions in the same manner to complete the locking action as in the normal closing mode. The other valves in the control module are positioned as when CLOSE is selected. The flow regulators in the open and close control modules of the hydraulic actuator also control the closing time for this mode of operation. After completion of boost mode operation, the canopy control handle shall be positioned to NORMAL close position; otherwise, depletion of nitrogen pressure from the canopy pneumatic reservoir will occur as shown in table 3-1. Table 3-1.—Nitrogen Pressure Depletion N2 Pressure (psi) Time Charged at 3,000 Initial time 0 1,000 After 1 minute 800 After 2 minutes 600 After 3 minutes 500 After 4 minutes AUXILIARY OPENING MODE The auxiliary opening mode is used to unlock the canopy when normal pneumatic system reservoir pressure drops below 225 psi. To prevent further depletion of nitrogen pressure in the normal system, a low-pressure sensor repositions valves no. 5 and 6 in the control module. The canopy must be unlocked by activating the auxiliary opening mode. When the control handle is set to AUX OPEN, the auxiliary unlock pneumatic release valve releases pressurized nitrogen from the auxiliary pneumatic reservoir. Nitrogen pressure from the reservoir flows through a 760 ± 30 psi pressure reducer through the release valve and pneumatic unlock shuttle valve, to shift position of the unlock shuttle internal spool. This directs nitrogen pressure to the unlock port of the canopy-lock pneumatic actuator, unlocking the canopy. Valve no. 1 in the control module directs reservoir pressure to open the transfer cylinder of the hydraulic actuator. This low-pressure nitrogen, acting against the transfer cylinder piston, counterbalances the weight of the canopy. The canopy can then be opened and closed manually with nominal effort; the canopy cannot be locked closed under these conditions. To return the system to normal operation, the control handle must be set to OPEN. The release valve eccentric cam must be manually reset to block auxiliary nitrogen pressure flow to the shuttle valve and to vent the pressure in the canopy-lock pneumatic actuator. Q3-11. How many modes of operation are there for the F-14 canopy system? Q3-12. In what mode can the canopy stop at a desired opening? 3-5

Q3-13. On a fully opened canopy, what is the approximate closing time? Q3-14. When reservoir pressure drops below 225 psi, what mode is used to unlock the canopy? CANOPY INFLATABLE SEAL SYSTEM LEARNING OBJECTIVE : Describe the canopy inflatable seal system and its compo- nents. The canopy inflatable seal system (fig. 3-2) provides an airtight seal between the canopy assembly and the aircraft structure to maintain cockpit pressurization. This section will cover the description, components, and operation of the canopy inflatable seal system. The system, using cooled engine bleed air from the service air heat exchanger core, inflates the canopy seal in response to movement of the canopy locking linkage. The system deflates the seal when the canopy is 3-6 M BOOTSTRAP TURBINE- COMPRESSOR TO ANTI-G , PRESSURE/ VENTILATION SUIT , EQUIPMENT PRESSURIZATION SYSTEMS AND SERVO AIR SUPPLY SERVO AIR GROUND CONNECTION SERVICE AIR HEAT EXCHANGER FROM EMERGENCY RAM AIR SYSTEM WARM AIR FROM PRIMARY HEAT EXCHANGER CANOPY INFLATABLE SEAL TO AVIONIC EQUIPMENT BAYS TEMPERATURE CONTROL SYSTEM RELIEF/ VENT PORT CANOPY SEAL PRESSURE REGULATOR 1 1 RELIEF VALVE STEM BELLOWS SHUTOFF VALVE BALL SEAT FLANGE PLUNGER INLET CHECK VALVEPRESSURE GAUGE TEST PORT NOTE LEGEND Warm Air Regulated Pressure Cool Air Mechanical Linkage Check Valve Canopy seal pressure regulator vents pressure from seals when plunger is depressed and pressurizes seals when plunger is released. Plunger is actuated by locking and unlock action of canopy. AMEf0 02 Figure 3-2.—Canopy inflatable seal system. 3

unlocked. On aircraft modified by AFC 581, the canopy structure also contains a flat rain seal to prevent water intrusion into the cockpit when the aircraft is in static conditions. COMPONENTS Components of the canopy inflatable seal system are the canopy inflatable seal and the canopy seal pressure regulator. Canopy Inflatable Seal The canopy inflatable seal (fig. 3-3) is retained in a channel around the circumference of the canopy assembly frame. When inflated, the seal fills the gap between the frame and aircraft structure. Canopy Seal Pressure Regulator The canopy seal pressure regulator (fig. 3-4) is on the turtle deck. It consists mainly of a check valve, shutoff valve, bellows, spring-loaded ball, and plunger. The regulator regulates its 80-psi bleed air input to the 25 ± 5 psi required by the canopy seal system, and controls inflation and deflation of the canopy inflatable seal. The regulator also receives pressures in excess of 6 to 8 psi above regulated value. 3-7 04 CANOPY SEAL PRESSURE REGULATOR OUTBD F W D VIEW LOOKING DOWN THROUGH ACCESS 20131-2 Figure 3-4.—Canopy seal pressure regulator location. AMEf03 CANOPY INFLATABLE SEAL RETAINER INFLATABLE SIDE CANOPY INFLATABLE SEAL TYPICAL CANOPY INFLATABLE SEAL REMOVED Figure 3-3.—Canopy inflatable seal (removed). AMEf0303

OPERATION The canopy seal pressure receives cooled engine bleed air, at approximately 80 psi, from the service air heat exchanger. When the canopy is closed and locked, the regulator plunger is released; this opens the shutoff valve. Air from the regulator inlet then flows past the check valve and shutoff valve, through the outlet port to the canopy inflatable seal. As air pressure in the seal increases, pressure buildup in the regulator chamber moves the bellows seat away from the flange. The interior of the bellows is vented to ambient. When pressure in the seal reaches 25 ± 5 psi above ambient, the bellows has moved sufficiently to seat the shutoff seal, which fills the gap between the canopy frame and the mating aircraft structure, preventing loss of cockpit pressure. If pressure downstream of the regulator increases to 6 to 8 psi above the regulated pressure, additional bellows movement causes the relief valve stem to unseat the ball in the seat to vent the excess pressure through the relief/vent port. The check valve prevents loss of pressure from the inflatable seal should the air supply to the system fail. When the canopy is unlocked, the regulator plunger is depressed. The plunger moves the bellows seat toward the relief valve stem to close the shutoff valve and unseat the ball, venting downstream pressure through the relief/vent port. Q3-15. What is the purpose of the canopy inflatable seal system? Q3-16. The canopy seal pressure regulator regulates 80-psi bleed air input down to what pressure? Q3-17. Where does the canopy seal system receive its pressure? Q3-18. What prevents loss of pressure should the air supply to the system fail? CANOPY EMERGENCY JETTISON SYSTEM LEARNING OBJECTIVE : Describe the components and operation of the canopy emer- gency jettison system. The canopy emergency jettison system jettisons the canopy clear of the cockpit during emergency conditions that necessitate seat ejection and/or ditching. The canopy is jettisoned clear of the cockpit for normal ejection mode. Through the use of pyrotechnics, the canopy is automatically unlocked and jettisoned when ejection is initiated. It also may be jettisoned without initiating ejection by the aircrew (with canopy jettison initiator handles in the aircraft) or by a groundcrew (with an external canopy jettison initiator handle at each side of the aircraft). Figure 3-5 3-8 Figure 3-5.—Canopy emergency jettison system components. NFINED DETONATING CORD (FCDC) (2) EXPLOSIVE MANIFOLD EXPLOSIVE MANIFOLD EXPLOSIVE MANIFOLDS EXPLOSIVE MANIFOLDS PILOT AFT BULKHEAD FORWARD BULKHEAD INERT CONNECTOR (TEE) (TYPICAL) INERT CONNECTOR (INLINE) (TYPICAL) INERT CONNECTOR (90 ) (TYPICAL) o 05 EXPANDING SHIELDED MILD DETONATING CORD (XSMDC) (20 CANOPY LOCK HOOKS (14)SHIELDED MILD DETONATING CORD (SMDC) EXPLOSIVE MANIFOLDS (13) ONE-WAY EXPLOSIVE TRANSFER (8) ONE-WAY EXPLOSIVE TRANSFER FLEXIBLE C FLEXIBLE CONFINED DETONATING CORD (FDC) (2) AMEf03

displays the canopy emergency jettison system com- ponents. The following paragraphs will discuss the components and operation of the canopy emergency jettison system. COMPONENTS Components of the emergency jettison system include pyrotechnic cords, internal and external canopy jettison initiators, shielded mild detonating cord (SMDC)/gas initiators, gas generators, inert connectors and manifolds, explosive manifolds, and one-way explosive transfers. Pyrotechnic Cords Three types of pyrotechnic cords are used in the F-14 escape systems: expanding shielded mild detonating cord (XSMDC), flexible confined detonating cord (FCDC), and SMDC. Two XSMDC cords are routed parallel through each side of the canopy sills. When charged, the cords expand diametrically and sever hardware in all 14 canopy lock hooks, freeing the canopy. The firing of the canopy gas generator then jettisons the canopy. The FCDC, which is used in areas requiring mechanical movement, connects the canopy jettison gas generator to the SMDC, and starboard XSMDC to port XSMDC. The SMDCs are rigid tubes located throughout the cockpit fuselage and bulkheads. Internal Canopy Jettison Initiators Two internal canopy jettison initiators enable the aircrewman to jettison the canopy during emergency conditions without initiating seat ejection. One initiator is actuated with the CANOPY JETTISON handle on the pilot right instrument panel; the other initiator, with the CANOPY JETTISON handle on the NFO right instrument panel. External Canopy Jettison Initiator An external jettison initiator (fig. 3-6) enables the groundcrew to jettison the canopy during ground emergency conditions. Each initiator is manually actuated with its external canopy jettison handle. Initiators (SMDC to Gas/Gas to SMDC) The system has four SMDC to gas (two pilot and two NFO) and four gas SMDC initiators (two pilot and two NFO). The initiators are behind each ejection seat, mounted on an initiator manifold and connected to each seat with a pyrotechnic quick-disconnect. The gas to SMDC initiators are activated by pyrotechnic gas signals which result from pulling the ejection control handle. They provide the initial explosive signal for canopy jettison and seat ejection. The SMDC to gas initiators are activated by the aircraft sequencing system, sending a gas signal to the seat to eject the crewmember. 3-9 CANOPY EXTERNAL JETTISON INITIATOR FS 248 VIEW LOOKING INBOARD Figure 3-6.—External canopy jettison initiator. AMEf0306

Canopy Jettison Gas Generator The canopy jettison gas generator (fig. 3-7) is attached to the lower end of the canopy actuator. The canopy jettison gas generator provides high-pressure gas to the canopy actuator to jettison the canopy from the aircraft. Inert Connectors and Manifolds Inert connectors and manifolds (fig. 3-5) throughout SMDC lines allow the interconnection of SMDC lines. Explosive Manifolds Explosive manifolds within SMDC line routing incorporate an internal explosive crossover that permits SMDC to fire both output SMDC lines. The manifolds also provide structural support for mounting the SMDC lines to the aircraft structure. One-Way Explosive Transfers One-way explosive transfers (fig. 3-5), within SMDC line routing, provide unrestricted explosive transfer in one direction only. If an explosive signal is introduced in the opposite direction, it is blocked. OPERATION Pulling the pilot or NFO ejection control handle initiates ejection. When the seat firing handle is pulled, a sear is pulled from dual redundant cartridges, sending a gas signal through the seat disconnect to the gas SMDC initiators mounted on the initiator manifold. This sends an explosive signal through SMDC lines to safe-and-arm firing pins, canopy-separation charge (XSMDC), and canopy jettison gas generator. XSMDC lines, routed through the latch hooks, break the canopy latch frangible bolts. This allows the hooks to rotate upward, releasing the canopy. The canopy jettison gas generator produces high-pressure gas that forces the canopy actuator shaft upward, ballistically jettisoning the canopy. As the canopy leaves the aircraft, the lanyard becomes taut and removes the sear. This fires an explosive charge within the safe-and-arm seat ejection module. This signal is routed to the ejection seat via the sequencing system SMDC lines to fire the SMDC to gas initiators. The SMDC to gas initiators send a gas signal through the pyrotechnic quick-disconnect, ejecting the crew- member by firing the primary cartridge. During ground emergency conditions, the canopy may be jettisoned clear of the cockpit by actuating the external canopy jettison initiator handle at either side of the aircraft. The pilot or NFO also may jettison it without initiating ejection with the internal canopy jettison handle. The explosive signal provided by the canopy jettison initiator is blocked from entering the SMDC lines of the seat ejection system by the one-way explosive transfers. Inert connectors joining the SMDC lines transfer the explosive stimuli through the bulkheads, straight runs, tee connections, and 90° bends. The canopy lock separates SMDC explosive manifolds within SMDC lines, which allows output SMDC lines to be initiated from one SMDC input. This assures system redundancy by providing dual-line initiation for the canopy-separation charge. Q3-19. What types of pyrotechnic cords are used in the F-14 escape system? Q3-20. What component enables the aircrewman to jettison the canopy during emergency condi- tions without initiating seat ejection? 3-10 AMEf0307 CANOPY HYDRAULIC ACTUATOR FLEXIBLE CONFINED DETONATING CORDS (FCDC) JETTISON CANOPY GAS GENERATOR Figure 3-7.—Canopy jettison gas generator.

Q3-21. What provides high-pressure gas to the canopy actuator to jettison the canopy? Q3-22. What component provides interconnection of SMDC lines? Q3-23. Explosive manifolds provide support for mounting the lines to the aircraft structure. Q3-24. What component prevents explosive transfer in one direction only? Q3-25. The external canopy jettison handles are used for what purpose? FRANGIBLE ESCAPE CANOPY SYSTEMS LEARNING OBJECTIVE : Describe the frangible escape system and its components. The S-3 aircraft frangible escape system (fig. 3-8) provides a means of escape from the aircraft for crewmembers after ditching or after a wheels-up landing by initiation of explosive charges to blow out windows and hatches. The emergency egress system uses SMDC instead of hot gas, as well as explosive charges instead of actuators found in hot gas systems. The S-3 emergency egress system is less susceptible to inadvertent actuation than hot gas systems, and more convenient and safer for maintenance per- sonnel. This section will describe the components and operation of the frangible escape canopy system. COMPONENT DESCRIPTION The emergency egress system consists of two window/hatch external jettison handle/initiators, three window/hatch internal jettison handles/initiators, window and hatch explosive charges, fillet-severance and fillet-support severance explosive-shaped charges, SMDC, FCDC, and SMDC one-way transfers. 3-11 SUPPORT SEVERANCE EXPLOSIVE-SHAPED CHARGE TRANSFER BLOCK (RIGHT OPPOSITE) PILOT/COPILOT WINDOW/HATCH INTERNAL JETTISON HANDLE/INITIATOR SMDC TUBING ASSEMBLY (TYP) LEFT SMDC ONE-WAY TRANSFER (RIGHT OPPOSITE) LEFT HATCH-SEVERANCE EXPLOSIVE CHARGE TRANSFER BLOCK (RIGHT OPPOSITE) LEFT FILLET- SEVERANCE EXPLOSIVE-SHAPED CHARGE TRANSFER BLOCK (RIGHT OPPOSITE) LEFT WINDOW-SEVERANCE EXPLOSIVE CHARGE TRANSFER BLOCK (RIGHT OPPOSITE) LEFT WINDOW/HATCH EXTERNAL JETTISON HANDLE/INITIATOR (RIGHT OPPOSITE) Figure 3-8.—Emergency egress system components and plumbing. AMEf0308 SENSO HATCH INTERNAL JETTISON HANDLE/INITIATOR TACCO HATCH INTERNAL JETTISON HANDLE INITIATOR LEFT FILLET FAIRING (RIGHT OPPOSITE) LEFT FILLET

Window/Hatch External Jettison Handle/Initiator Two external jettison initiators (fig. 3-9) are installed inside access doors on each exterior side of the aircraft just below and forward of the windshield aft posts. The external jettison initiator is a mechanically fired device, with the firing pin relaxed (not precocked) before handle actuation. The sear mechanism is a conventional ball-and-node type, which disengages completely after 3/4 inch of travel. During travel, the firing pin withdraws, but the handle does not disengage. The primer fires into a lead charge, which fires the output charge. The external jettison initiators have no safety pins, but use a 10-foot lanyard to protect against inadvertent initiation. Any partial withdrawal of the handle from the external jettison initiator is cause for rejection and replacement. Either external initiator will cause all windows, hatches, fillets, and fillet supports to blow away from the aircraft. Window/Hatch Internal Jettison Handle/Initiator Three internal jettison initiators (fig. 3-10) are located in the crew compartment: one at the eyebrow panel and one each at the tactical coordinator (TACCO) and sensor operator (SENSO) instrument panels. The internal jettison initiators are the squeeze-to-pull type, which have a quick-release safety pin in the squeeze segment of the operation for safetying. The pilot/copilot handle will blow all windows and hatches, whereas the TACCO and SENSO handles will blow only the hatch above the crewmember. The basic internal jettison initiators are similar to the external jettison initiators except for the handle and the absence of the lanyard feature. Window-Severance Explosive Charge An explosive charge is attached to the inside periphery of the pilot and copilot windows. An SMDC or FCDC connects to a transfer block at the lower front corner of the explosive charge. The window explosive charge is actuated by the pilot/copilot internal jettison initiator or by either external jettison initiator through the SMDC and FCDC segments. The explosive charge acts as the cutting device for the window glass. Hatch-Severance Explosive Charge The hatch explosive charge is similar to the window explosive charge. The explosive charges of the 3-12 Figure 3-9.—External canopy and hatch jettison initiator. AMEf0309 INITIATOR (INSTALLED) DOOR CAP BOOSTER ASSY OUTLET PORT FOR SMDC ASSY BODY FIRING PIN WIRE LANYARD (10 FT) SEAR PINSHIELD HANDLE PULL HATCH SEVERANCE

hatches can be actuated by the external jettison initiators or by the pilot/copilot internal jettison initiator. The TACCO or SENSO hatch explosive charges can be actuated individually by the respective TACCO or SENSO handle/initiator. Fillet-Severance Explosive-Shaped Charge Each right and left upper wing-to-fuselage fillet has an explosive-shaped charge attached near the outer and rear fillet attachments (fig. 3-11). The explosive-shaped charge cuts the attached fillet from the aircraft to allow complete egress of the respective hatch. A fillet support is cut by a second explosive-shaped charge attached at the bottom. The fillet-support severance explosive-shaped charge is attached at the bottom of the internal fillet support to cut the support, allowing the fillet to separate from the aircraft during the emergency egress system operation. 3-13 Figure 3-11.—Fillet FLSC assembly. CAP SPRING TRANSFER BOOSTER ASSEMBLY OUTLET PORT FOR SMDC ASSEMBLY SAFETY PIN SEAR PIN FIRING PIN BODY AMEf0310 Figure 3-10.—Internal canopy and hatch jettison initiator. AMEf0 113 FILLET HATCH CANOPY CHARGE HOLDER (SILICONE RUBBER) VOID FIBERGLASS RETAINER FLEXIBLE LINEAR SHAPED CHARGE (LEAD SHEATH) SQUEEZE-TO-PULL TYPE HANDLE QUICK-RELEASE PIN STRUCTURE INTERNAL HANDLE INITIATOR

Shielded Mild-Detonating Cord and Flexible Confined Detonating Cord The SMDC and FCDC segments act as the plumbing for the emergency egress system. The SMDC and FCDC connect all external and internal jettison initiators; all connectors, tees, and manifolds or one-way transfers; all explosive charges; and all explosive-shaped charges. When initiated, the extremely high velocity and pressure of the cord is focused onto the end of the next adjacent SMDC segment, which acts as acceptor charge. Shielded Mild-Detonating Cord One-Way Transfer Two SMDC one-way transfers are located on the pilot and copilot bulkhead. The SMDC one-way transfer acts as a check valve or one-way detonating transfer device. The SMDC one-way transfer is a self-contained unit housing a sealed receptacle for dual-shaped charges. Any detonating entering the in ports will transfer to the out port. Any detonation originating from the aft port (TACCO or SENSO) segment of the SMDC one-way transfer will not transfer forward. This would occur when either the TACCO or SENSO elects to cut the respective hatch; the remaining two windows and the opposite hatch would not be affected. OPERATION The emergency egress system is initiated from any one of the five positions: two on the outside of the flight station, and three located in the crew compartment at the eyebrow panel and at the TACCO and SENSO instrument panels. All windows and hatches are cut and blown outward by the actuation of either external jettison initiator and by the pilot/copilot internal jettison initiator. The TACCO and SENSO internal jettison initiators cut only the respective panel next to the crewmember. The emergency egress system is used primarily for ground and water rescues. The handle/initiators have a trigger action. Once the emergency egress system is actuated, the emergency egress system will respond to completion without further action by crewmembers. The functional sequence is from the handle/initiator (anyone), to the SMDC, to the explosive charge, which is the actual cutting tool for the window or hatch glass. If either or both the TACCO and SENSO hatches are to be blown, the respective fillet and fillet support will be cut to allow complete egress of the hatch. When either the TACCO or SENSO crewmember actuates the handle/initiators, the opposite hatch and the two flight stations windows will not be cut, since the SMDC one-way transfer (check valve) restricts transfer of pyrotechnic energy flow in one direction. The emergency egress system is entirely self-sufficient and completely independent. The emergency egress system does not depend on any other aircraft system, nor does the emergency egress system air, assist, or sequence with another system. The SMDC is considered to be more reliable and much faster than a comparable hot gas system. The emergency egress system is safer from the standpoint of inadvertent actuation due to the extremely high initiating velocities and pressures. The high operating velocity is much too fast to permit emergency egress system initiation by ordinary sawing, filing, drilling, or hammering. With quick-release safety pins properly installed, the emergency egress system is virtually inert. Q3-26. What is the purpose of the frangible escape system? Q3-27. The S-3 emergency egress system is more susceptible to inadvertent actuation than hot gas systems. True or false? Q3-28. Instead of safety pins, the external jettison initiators use what type of component to protect against inadvertent initiation? Q3-29. How many internal jettison initiators are located in the crew compartment? Q3-30. The and connect all external and internal jettison initiators. Q3-31. What component restricts transfer of pyrotechnic flow in one direction? Q3-32. The emergency egress system is virtually inert when what component is properly installed? 3-14

CHAPTER 3 ANSWERS TO REVIEW QUESTIONS A3-1. Pneumatic pressure from externally serviced reservoirs A3-2. Reference mark A3-3. Acrylic A3-4. Hydraulically A3-5. It regulates the speed of the canopy-lock pneumatic actuator during locking and unlocking of the canopy. A3-6. 225 psi A3-7. (a) 225 cubic inch, (b) 3,000 psi A3-8. Reservoir relief valve A3-9. Downstream of the auxiliary pneumatic reservoir A3-10. Three-port pressure operated A3-11. Five A3-12. Hold A3-13. 10 seconds A3-14. Auxiliary opening A3-15. To provide an airtight seal between the canopy assembly and the aircraft structure to maintain cockpit pressurization A3-16. 25 ± 5 psi A3-17. Service air heat exchanger A3-18. Check valve A3-19. XSMDC, FCDC, and SMDC A3-20. Internal canopy initiators A3-21. Canopy jettison gas generator A3-22. Inert connectors and manifolds A3-23. SMDC A3-24. One-way explosive transfers A3-25. Ground emergency conditions A3-26. Provides a means of escape from the aircraft for crewmembers after ditching or after a wheels-up landing by initiation of explosive charges to blow out windows and hatches A3-27. False A3-28. 10-foot lanyard A3-29. Three 3-15

A3-30. SMDC, FCDC A3-31. SMDC one-way transfer valve A3-32. Safety pins 3-16

CHAPTER 4 EXPLOSIVES HANDLING PERSONNEL QUALIFICATION AND CERTIFICATION PROGRAM Improper handling, loading, processing, disposal, demilitarization or testing of explosive devices has resulted in many mishaps with injuries, loss of life, damage amounting to millions of dollars, and reduced operational effectiveness. The purpose of this program is to eliminate these mishaps through proper qualification and certification of personnel. ORDNANCE CERTIFICATION OVERVIEW NOTE: The Explosives Handling Personnel Qualification and Certification (Qual/Cert) Program is governed by the OPNA VINST 8020 instruction, which directs type com- manders (TYCOMs) to issue a Qual/Cert instruction for their cognizant commands. This chapter was referenced using the OPNA VINST 8020.14 joint instruction for COMNA V AIRPAC, COMNA V AIRLANT, COMNA VRESFOR, and CNATRA. LEARNING OBJECTIVE: Identify the pur- pose and terminology of the Explosives Handling Personnel Qualification and Certification Program, OPNA VINST 8020.14. The intent of the Qualification/Certification (Qual/Cert) Program is to ensure that before an individual performs any task involving explosives/explosive devices, they are qualified and formally certified by the command to which they are assigned. Each person must satisfactorily demonstrate the qualifications to properly and safely perform all required functions and tasks involving the explosives/explosive device. Accident-free explosive operations require command attention that includes certified workers, direct supervision, use of standard operating procedures (SOP), technical manuals and checklists for the task at hand, and a total quality assurance (QA) process where required. When properly managed and used, this program assures qualification of all personnel who work with explosives/explosive devices. This section will describe the background of the ordnance program and definitions of program terminology. BACKGROUND The Explosives Handling Personnel Qualification and Certification Program was established by the Chief of Naval Operations as a result of the catastrophic MK-24 parachute flare accident on the USS ORISKANY in 1966 that led to significant loss of life and major ship damage. The flag board of inquiry concluded the accident was attributed to a lack of training, direct supervision, and a method to determine personnel qualifications prior to being authorized to handle explosives. Qual/Cert, with proper oversight and management, can prevent similar accidents. Although Qual/Cert has been in effect for over 30 years, improper handling, loading, processing, or testing of explosive devices continues to result in death, injury, and extensive high-dollar damage to equipment. Research has shown personnel error due to inadequate training, lack of adequate supervision, lack of or inadequate SOP, or just plain failure to follow the governing technical directives causes the majority of explosive mishaps. Qual/Cert is intended to be the cornerstone for a ZERO DEFECT SAFETY PROGRAM. DEFINITIONS NOTE: All explosives, ammunition, weapons, and devices using conventional ex- plosives, pyrotechnics, or incendiary material for their operation are included in the general term explosive devices. Before you read about ordnance certification, you need to know the terminology that will be used in this discussion. The following definitions will help when working with the Qual/Cert program and completing the ordnance certification format (fig. 4-1). Storage/Stowage . Physical act of stowing explosives/explosive devices in designated and approved magazines and ready service lockers. Demonstrated knowledge of afloat/ashore storage/stowage requirements per applicable instructions/directives. 4-1

5-2 Figure 5-1.—Bleed air leak sensing element loop schematic diagram.

Engine Start Port Leak Detector The leak detector is mounted inside the right main landing gear door. The leak detector is a heat-sensitive element that completes a ground circuit when subjected to temperatures in excess of 225°F. Its purpose is to detect leakage from the engine ground start port in the event of a check valve failure. The leak detector is wired in parallel with the loop 2 (2 BL LEAK) sensing elements. OPERATION The bleed air leak detection system is powered by a single-phase, 400-hertz (Hz), 115-volts alternating current (Vac) power from the essential ac bus. The test circuit uses 28 volts direct current (Vdc) power from the essential bus. When the bleed air leak detect switch on the elect panel is held in the TEST position, 28 Vdc is applied to the test relays. This completes the transformer circuit through the sensing elements to ground. The transformer conducts and applies a signal to a transistor circuit, which closes control relays. A ground circuit is completed through the control relay contacts to turn on the 1 BL LEAK, 2 BL LEAK, CAB BL LEAK, and APU BL LEAK indicator lights on the annunciator panel. When the momentary BLEED AIR LEAK DETECT switch is released to the OFF position, the annunciator panel indicator lights go off. In normal operation, when the temperature of a section or a short segment of the sensing element exceeds 255°F, the chemical in the tube conducts electric current, which completes a transformer circuit to ground similar to the test relay. The indicator light on the annunciator panel will come on to indicate the loop is overheating. This system will function even if there is an open (break) in the loop. During test position, the open element will prevent the indicator light from turning on. The individual loops will function separately or simultaneously if a leak is located in an area common to two loops. This will allow the pilot to take action to minimize damage due to bleed air leakage. Q5-3. Describe an S-3 aircraft bleed air leak detection system. Q5-4. During normal operation, describe what happens when the temperature in the sensing element exceeds 225°F . Q5-5. What are the major components of a bleed air leak detection system? Q5-6. How many modules make up the bleed air leak detector control? ANTI-ICING SYSTEMS LEARNING OBJECTIVE : Recognize the operating principles and components for an anti-icing system. On days when there is visible moisture in the air, ice can form on aircraft leading edge surfaces at altitudes where freezing temperatures start. Water droplets in the air can be super-cooled to below freezing without actually turning into ice unless they are disturbed in some manner. This unusual occurrence is partly due to the surface tension of water droplet not allowing the droplet to expand and freeze. However, when aircraft surfaces disturb these droplets, they immediately turn to ice on the aircraft surfaces. The ice may have a glazed or rime appearance. Glazed ice is smooth and hard to detect visually. Rime ice is rough and easily noticed. Frost is formed as a result of water vapor being turned directly into a solid. Frost can form on aircraft surfaces in two ways. First, it can accumulate on aircraft parked in the open and overnight when the temperature drops below freezing and proper humidity conditions exist. Second, it can form on aircraft surfaces, caused by flying at very cold altitudes and descending rapidly into warm, moist air. In this case, frost deposits will result before the structure warms up because of the marked cooling of air adjacent to the cold skin. Ice or frost forming on aircraft creates two basic hazards: • The resulting malformation of airfoil, which could decrease the amount of life; and • The additional weight and unequal formation of the ice, which could cause unbalancing of the aircraft, making it hard to control. Enough ice to cause an unsafe flight condition can form in a very short period of time; thus some method of ice prevention or removal is necessary. An anti-icing system is designed to prevent ice from forming on the aircraft. A deicing system is designed to remove ice after it has formed. An example of this is the deice boot system for the E-2 aircraft. An aircraft anti-ice system removes ice from propellers and the leading edges of wings and stabilizers. These systems may use electrical heaters, hot air, or a combination of both to remove the ice formation. As an AME, you are primarily concerned with hot air as a method to remove the formation of ice on wings and stabilizers. The P-3 wing anti-icing system is used as an example in this chapter to describe a hot-air system. 5-3

The P-3 aircraft uses an ice detector system to warn the pilot, visually, of an icing condition. A warning light is installed on the center instrument panel in the flight station. COMPONENTS The hot bleed air is directed and regulated to the leading edge ejector manifold through shutoff valves, modulating valves, thermostats, skin temperature sensors, and overheat warning sensors (fig. 5-2). Shutoff Valves The wing anti-ice system contains several shutoff valves. The fuselage bleed air shutoff valves, installed in the cross-ship manifold on the right and left wings, isolate the wings from the fuselage duct section. In addition, they may be used to isolate one wing duct from the other wing duct. Each valve is individually controlled by a guarded toggle switch mounted on the bleed air section of the ice control protection panel. A bleed air shutoff valve is also installed in each engine nacelle. These shutoff valves are physically identical. They are of the butterfly-type and are actuated by an electric motor. An indicator, located on top of the valve housing, shows the position of the valve—open or closed. This indicator enables you to visually check the operation of the valve while it is still installed in the anti-ice system. Modulating Valves The P-3 anti-icing system has three modulating valves installed in each wing. These valves are thermostatically controlled and pneumatically operated. They maintain the constant engine compressor bleed air temperature required for the wing leading edge. When anti-icing is not required, the valves operate as shutoff valves. The modulating valves (fig. 5-3) have pilot solenoid valves that are electrically controlled by three switches on the bleed air section of the ice protection panel. When the solenoid is energized, it admits filtered, regulated, bleed air pressure to one side of a diaphragm chamber in the valve. The other side of the diaphragm chamber is spring-loaded to the closed position. Movement of the diaphragm operates a main line butterfly valve. When the valve opens, hot air is admitted to the leading edge distribution system. The hot air goes 5-4 Figure 5-2.—Wing leading edge anti-icing cross section.

through the modulator valve to the ejector manifold, out the jet nozzles, and into the wing leading edge plenum area. The bleed air is then directed across a pneumatic thermostat. Increased temperature across the thermostat actuates the sensor and opens a bleed passage from the diaphragm chamber. This reduces the pressure on the diaphragm and allows a spring to close the main valve. Thermostats The wing leading edge pneumatic thermostat is installed adjacent to each modulating valve (fig. 5-2). The thermostat controls air pressure on the modulating valve diaphragm, and thereby controls the valve opening. The unit is composed of a probe and a valve assembly (fig. 5-4). The probe is a core made of layers 5-5 Figure 5-3.—Anti-icing modulating valve. Figure 5-4.—Wing leading edge thermostat.

of high- and low-expansion material that is locked to a sliding piston. In addition, the piston contains an override spring and ball-type metering valve. Airflow from the leading edge flows over the core and causes the materials to expand or contract. As temperature rises, the core pulls the piston and metering ball from the seated position. This allows pressure from the modulating valve diaphragm to vent. Increasing temperature causes more air to be bled from the diaphragm chamber. Because of spring action, the modulating valve moves toward the closed position. This restricts flow through the modulator valve and drops the skin temperature. The thermostats in the outboard leading edge plenum areas are set at 145°F. The wing inboard and center section thermostats are set at 120°F. Leading Edge Skin Temperature Indicator and Overheat Circuit Caution Light Circuit The temperatures of the wing leading edge sections are displayed on the LEAD EDGE TEMP indicator on the engine bleed air control panel. Six sensors are used in the system, one in each leading edge section. These sensors form part of the circuitry of the airfoil temperature sensors amplifier. When the temperature at one or more of the sensors exceeds 230°F, a relay energizes, providing a ground for the LE HOT caution light circuit, causing the light to come on. Whenever a leading edge skin overheat condition is detected, the location can be determined by setting WING LEADING EDGE SKIN TEMP BOMB BAY TEMP rotary switch to each position while observing the indicator. Since there is always a possibility of more than one section overheating, all six-wing leading edge sections should be checked. The airfoil temperature sensor amplifier is at the forward load center and is powered through the AIRFOIL IND & OVHT W ARNING circuit breaker. The circuit receives power from the AIRFOIL IND & OVHT W ARNING circuit breaker. The caution light is energized through the indicator lights power system and the indicator light control. The indicator circuit does not disturb the caution function of the system. High temperature within the leading edge is generally caused by bleed air leakage or malfunctioning modulator valves. You can detect the portion of the leading edge that has the over-temperature by placing the rotary selector switch, located on the ice control protection panel (fig. 5-5), to the different sensor positions: INBD (inboard), CTR (center), and OUTBD (outboard). The temperature at the selected sensor is then read at the indicator adjacent to the rotary switch. An excessive temperature reading on the indicator denotes a malfunction within the area being tested. OPERATION The P-3 aircraft wing anti-icing system prevents ice formation on wing leading edges during icing conditions. This is a hot wing type system utilizing hot compressed air from the engines. Engine bleed air, ducted from two ports at the 14th stage of each engine compressor, is orifice regulated. The supply is maintained at essentially a fixed percentage of engine airflow for all flights speeds and attitudes. The air from both ports, after passing through the two 14th stage duct check valves, is ducted through a single universal flexible joint to the bleed air shut-off valve aft of the 14th stage firewall (fig. 5-6). The bleed air section of the ice protection panel in figure 5-5 shows a basic diagram of the wing anti-ice system. An engine number labels each engine. Directly below each engine block (in the diagram) is an OPEN light that illuminates when the bleed air valve is open 2 degrees or more. The cross-ship manifold from the bleed air valves goes to each modulating valve and the fuselage shutoff valves. The fuselage bleed air shutoff valves are normally in the CLOSE position during normal anti-icing operation. The bleed air pressure gauge reads cross-ship manifold pressure when one or both switches are opened. A leak test switch is mounted on the upper right-hand side of the panel. This switch is used to determine if the leakage of the system is acceptable. Three modulating valve control switches are located on the left side of the wing and empennage ice panel. The OUTBD switch controls the outboard modulating valve on the left and right wing, the CTR switch controls the two center modulating valves, and the INBD switch controls the two inboard modulating valves. 5-6

5-7 Figure 5-5.—Engine bleed air and anti-icing control panels.

5-8 Figure 5-6.—P-3 wing anti-icing system schematic.

During normal operation of the anti-icing system, all four-engine bleed air valves are open to supply bleed air to the cross-ship manifold, and both fuselage bleed air shutoff valves are closed. The modulating valves, which are controlled by pneumatic thermostats, maintain a controlled flow of bleed air to the leading edge distribution system. The complete system is monitored for hot spots by heat-sensing switches. Before flight, the anti-icing manifold system may be tested for leakage. This leak test is performed by pressurizing the system: OPEN the No. 4 engine bleed air valve; the Nos. 1, 2, and 3 engine bleed air valves remain CLOSED, and both fuselage shutoff valves are in the OPEN position. When the bleed air pressure on the bleed air manifold reads 70 psi, the No. 4 engine bleed air valve is closed and the leak test switch is actuated. As the bleed air pressure drops, the time-delay relay will illuminate the ACCEPT light after an 8-second delay if the system is tight. The light will go out when the test switch is released. Q5-7. Describe the difference between an anti-icing system and a deicing system. Q5-8. In an anti-ice system, what method(s) are used to remove ice formation? Q5-9. Identify the four major components of a P-3 anti-ice system. Q5-10. The OPEN light on the ice protection panel will illuminate when what condition occurs? WINDSHIELD ANTI-ICE/RAIN REMOV AL SYSTEM LEARNING OBJECTIVE : Recognize the components and operating principles for a windshield anti-ice/rain removal system. This system is designed to provide a means of maintaining visibility from the aircraft. The F-18 windshield anti-ice/rain removal system is typical of systems found in jet aircraft. This system supplies controlled temperature air from the air cycle air-conditioning system (ACS) to provide airflow over the external surface of the windshield for rain removal and windshield anti-icing. COMPONENTS Components of the windshield anti-ice/rain removal system include a warm air temperature control valve, temperature sensors, a flow/temperature limiting anti-ice modulating valve, an air control regulating valve, and an anti-ice/rain removal switch. Warm Air Temperature Control Valve The warm air temperature control valve operates to control temperature entering the windshield anti-ice and rain removal ducts. The valve is modulated by muscle pressure, which is controlled by the warm air temperature sensor. Warm Air Temperature Sensor The warm air temperature sensor (fig. 5-7, item A) is located downstream of the warm air temperature 5-9 Figure 5-7.—Windshield anti-ice and rain removal system component locator.

control valve and opens to prevent muscle pressure to the warm air temperature control valve when duct temperature exceeds sensor settings. Flow/Temperature Limiting Anti-Ice Modulating Valve The flow/temperature limiting anti-ice modulating valve (fig. 5-7, item B), located downstream of the warm air temperature control valve, is a dual function valve. It is a pneumatically actuated flapper valve and a muscle pressure that is controlled by the warm air over-temperature sensor. The valve is normally open during system operation and modulates toward closed only if an over-temperature condition occurs. The muscle pressure regulator on this valve is the source of regulated muscle pressure used by the environmental control systems. It is a dual diaphragm regulator and uses source air pressure from either the windshield anti-ice and rain removal duct or the air cycle air-conditioning system, depending on which pressure is greater. Warm Air Over-Temperature Sensor The warm air over-temperature sensor (fig. 5-7, item C) is located downstream of the flow/temperature limiting anti-ice modulating valve. It opens if duct temperature reaches 375°F ±25°F to vent muscle pressure from the flow/temperature limiting anti-ice modulating valve. This causes the valve to modulate toward closed and restricts airflow to protect the windshield from overheat damage. Anti-Ice/Rain Removal Air Control Regulating Valve The anti-ice/rain removal air control-regulating valve (fig. 5-8) completes the final pressure regulation and flow control before airflow reaches the anti-ice/rain removal nozzle. The valve regulates pressure and flow rate relative to position of the WINDSHIELD ANTI-ICE/RAIN removal switch. Windshield Overheat Temperature Sensor The windshield overheat temperature sensor, located downstream of the anti-ice/rain removal air control regulating valve, is a temperature-activated switch, which opens if airflow temperature reaches 290° ±5°F. It closes when airflow temperature drops to 280° ±5°F. When the switch is open, a ground is lost to the signal data converter and the signal data computer, causing the digital display indicator to display a WDSHLD HOT caution message. Windshield Anti-Ice/Rain Removal Switch This is a three-position control switch. The switch in OFF position removes power from the anti-ice/rain removal air control regulating valve to close the valve and shutoff airflow to the windshield. The switch in RAIN position allows low pressure (5.4 pounds per square inch gauge [psig]) and low volume (20 pounds per minute [lbs/min]) air at 250°F directed across the windshield through the anti-ice/rain removal nozzle. The switch in ANTI-ICE position allows high pressure (29.5 psig) and high volume (57 lbs/min) air at 250°F directed across the windshield through the anti-ice/rain removal nozzle. OPERATION The windshield anti-ice and rain removal system is used to supply controlled airflow to the anti-ice/rain removal nozzle to remove ice and/or rain from the windshield. The WINDSHIELD ANTI-ICE/RAIN removal switch controls the modes of operation. 5-10 Figure 5-8.—Anti-ice/rain removal air control regulating valve.

Rain Removal Positioning the WINDSHIELD ANTI-ICE/RAIN removal switch to RAIN controls the rain removal mode of operation. This will actuate the low pressure solenoid of the anti-ice rain removal air control regulating valve to supply low pressure (5.4 psig) and low flow (20 lbs/min) air at 250°F to the windshield. Windshield Anti-Ice Positioning the WINDSHIELD ANTI-ICE/RAIN removal switch to ANTI-ICE controls the anti-ice mode of operation. This will actuate the high pressure solenoid of the anti-ice rain removal air control regulating valve to supply high pressure (29.5 psig) and high flow (57 lbs/min) air at 250°F to the windshield. Q5-11. What is the purpose of an F-18 windshield anti-ice/rain removal system? Q5-12. Name the seven major components of an F-18 windshield anti-ice/rain removal system. Q5-13. What component controls the temperature entering the windshield anti-ice and rain removal ducts? Q5-14. The modes of operation for the anti-ice/rain removal system are controlled by what component? WINDSHIELD-W ASHING SYSTEM LEARNING OBJECTIVE : Recognize the components and operating principles for a windshield-washing system. The windshield-washer system on an EA-6B is typical of this system and provides cleaning for the pilot’s windshield. The WINDSHIELD switch located on the DEFOG/ANTI-ICE & RAIN REMOV AL control panel controls the windshield-washing system. The system cleans the windshield by directing a stream of 50 percent water-methyl alcohol mixture over the outside surface of the glass. The water-methyl alcohol is dried by engine bleed air through the rain-removal nozzles. The system uses cooled bleed air supplied by the auxiliary heat exchanger of the forward refrigeration unit to pressurize the windshield-washing tank, which stores the washing fluid. The pressure forces the windshield-washing fluid through a series of five nozzles located at the base of the pilot’s windshield. The windshield-washing shutoff valve controls the cool bleed airflow to the top of the windshield-washing tank. COMPONENTS Components of the windshield-washing system include a shutoff valve, tank, switch, and a nozzle assembly. Windshield-Washing Shutoff Valve The windshield-washing shutoff valve is mounted to a bracket on the right wing beam in the forward air-conditioning compartment (fig. 5-9). It is a solenoid-operated valve that controls air pressure to the windshield-washing tank. The WINDSHIELD switch on the DEFOG/ANTI-ICE & RAIN REMOV AL PANEL controls operation of the valve. The valve consists of a pressure-reducer valve, a check valve, a solenoid-operated combination shutoff and dump valve, and relief valve. When the solenoid is deenergized, the valve is closed and the outlet port is vented to the atmosphere. This shuts off the flow of cooled bleed air to the windshield-washing tank and reduces the pressure in the tank to zero. When the solenoid is energized, the valve opens and regulates the pressure of cooled bleed air to the windshield-washing tank at 10 ±1 psig. If the pressure in the tank goes above 13 ±0.5 psig, a relief valve inside the valve opens and pressure in the tank is reduced. 5-11 Figure 5-9.—Windshield-washing shutoff valve.

Windshield-Washing Tank The windshield-washing tank is built into the outside structure of the right engine inlet duct. A windshield-washing tank cap is removed to fill the tank. The tank holds 1 1/2 gallons of washing fluid, which is a mixture of 50 percent methanol (methyl alcohol) and 50 percent water. Windshield Switch The WINDSHIELD switch is a single-pole, three-position switch mounted on the DEFOG/ANTI-ICE & RAIN REMOV AL PANEL (fig. 5-10). The three positions are OFF, AIR, and W ASH. This switch controls the operation of the windshield-washing shutoff valve and rain-removal pressure-regulator shutoff valve. The WINDSHIELD switch is momentarily in either W ASH or AIR position. When released, the switch returns to OFF. Placing the switch to W ASH directs streams of washing fluid against the base of the pilot’s windshield; placing the switch at AIR directs a wide stream of hot air across the glass. Windshield-Washing Nozzle Assembly The windshield-washing nozzle assembly consists of five nozzles connected to a common inlet tube (fig. 5-11). The nozzles protrude through the rain-removal nozzle assembly at the base of the pilot’s windshield. OPERATION The WINDSHIELD switch controls the windshield-washing system. Holding the switch to W ASH routes 28 Vdc to open the windshield-washing shutoff valve. With the valve open, regulated air pressure from the auxiliary heat exchanger of the forward refrigeration unit is routed to the top of the windshield-washing tank. The valve controls the pressure in the tank at 10 ±1 psi. If the pressure in the tank exceeds 13 ±0.5 psi, the relief portion of the shutoff valve opens, reducing tank pressure. The 10-psi air pressure in the windshield-washing tank forces the mixture of 50 percent methyl alcohol and 50 percent water through five nozzles of the windshield-washing assembly. Releasing the WINDSHIELD switch allows it to return to OFF. This closes the windshield-washing shutoff valve and the supply of air to the windshield-washing tank. Excess pressure in the tank is vented into the atmosphere. Q5-15. Describe the mixture content on an EA-6B windshield-washer system. Q5-16. What type of valve is the windshield-washing shutoff valve? Q5-17. What event takes place if the pressure in the windshield-washing tank goes above 13 ±0.5 psig? Q5-18. What is the capacity of the windshield-washing tank? ANTI-G SYSTEM LEARNING OBJECTIVE : Recognize the components and operating principles for an anti-g system. The anti-g system automatically regulates air-pressure to the pilot anti-g suit. The anti-g suit reduces the fatiguing effect of repeated exposure to positive or negative g-forces that can cause grayout and/or blackout. The anti-g system also provides a method by which the pilot can relieve fatigue and physical tension during extended flight. Air pressure to the anti-g system is supplied from the air cycle air-conditioning system. 5-12 Figure 5-10.—Windshield switch. Figure 5-11.—Windshield-washing nozzle assembly.

Most anti-g systems are similar to the one illustrated in figure 5-12. This system consists of a supply line, an air filter, a pressure regulating valve, a connecting hose, and a suit attachment fitting (single quick-disconnect or composite quick-disconnect). The air pressure used in this system may be taken directly from the engine compressor bleed air ducting, but is usually taken off the air-conditioning ducting downstream from the heat exchanger. COMPONENTS Components of the anti-g system include a valve, a system filter, and quick-disconnects. Anti-g Valve The anti-g valve (fig. 5-13) is automatically controlled by any positive or negative g-force. The anti-g valve receives air from the high-pressure bleed system and regulates it to a maximum of 10 psi for delivery to the g-suit. The anti-g valve incorporates an internal demand, exhaust, and relief valve. The internal relief valve relieves excessive suit pressure and maintains pressure at a maximum of 11 psi. When a force of approximately 1.5 g’s is exerted on the aircraft, the activating weight overcomes the upper spring tension and closes the exhaust valve (fig. 5-14, 5-13 Figure 5-12.—Anti-g system. Figure 5-13.—Anti-g pressure regulating valve. Figure 5-14.—Anti-g valve operation.

view A). As the weight travels downward, it further depresses the valve assembly, forcing the demand valve from its seat, thus overriding the pressure of the lower spring and opening the demand valve. Air pressure then flows past the open demand valve, through the valve outlet into the valve outlet line, through the suit quick-disconnect, and into the anti-g suit. As the g-forces being applied to the aircraft are stabilized and become constant, the pressure under the activating weight diaphragm builds up sufficiently to lift the weight and to reduce the pressure on the valve assembly enough to close the demand valve (fig. 5-14, view B). The demand valve closes under pressure of the heaver lower spring, while the exhaust valve remains closed by the activating weight. The suit pressure is then trapped in the pressure outlet chamber of the anti-g valve and remains constant until the g-forces change. As the g-forces decrease, the downward force on the activating weight diminishes to a point at which the upper spring lifts the weight off the exhaust valve. The pressure in the suit is then vented through the exhaust port (fig. 5-14, view C) into the cockpit. Pressing the button at the top of the valve manually operates the anti-g valve. This button should be used to test the anti-g system prior to takeoff. Intermittent manual operation of the anti-g valve is performed during flight to relieve leg stiffness and static fatigue. Anti-G System Filter Most anti-g systems use a filter to prevent particles of dust, trash, and other foreign material from entering the regulating valve. This filter may be located in the supply line or it may attach to the anti-g valve on the inlet side. A typical anti-g system filter is shown in figure 5-15. Quick-Disconnects The anti-g suit is connected to the anti-g system by means of a quick-disconnect coupling. This quick-disconnect may be either a single unit that connects the anti-g suit only, or it may be a composite quick-disconnect that connects the pilot to the various personal service lines (oxygen, ventilating air, anti-g system, and communications). The anti-g system quick-disconnect is used on aircraft that are not equipped with a composite quick-disconnect attached to the ejection seat. This disconnect is on a hose that protrudes through the pilot’s console. It is attached by a flexible hose to the outlet port of the anti-g valve. This disconnect may be pulled up to a bumper stop to aid in connecting the anti-g suit hose. A spring-loaded cover on the disconnect prevents the entry of foreign material when the system is not in use. OPERATION As high-g conditions occur, the anti-g valves activating weight is forced down to close the exhaust valve and open the demand valve. This allows cooled engine bleed air from the refrigeration system service heat exchanger to flow through the anti-g valve, where it is regulated, to inflate the g-suit. Pressure to the g-suit is varied in proportion to the g-force acting upon the aircraft and crewmembers, to a maximum of 10 psi. As g-forces decrease, the activating weight is forced upward by spring tension. This reduces the pressure of the airflow to the g-suit and exhausts excess suit pressure into the cabin. As this occurs, the demand valve closes, blocking air from the g-suit. Q5-19. Identify the purpose of an anti-g system. Q5-20. Most anti-g systems consist of what compo- nents? Q5-21. The anti-g valve regulates high-pressure bleed air to what maximum pressure for delivery to the g-suit? Q5-22. Describe the operation of an anti-g system. VENT-AIR SYSTEM LEARNING OBJECTIVE : Recognize the components and operating principles for a vent-air system. Vent-air systems provide a flow of air to the aircraft’s seat or back cushions or to the ventilating air 5-14 Figure 5-15.—Anti-g system filter.

connection of the anti-exposure suit when worn by the pilot and/or crewmembers. The system provides a measure of personal comfort, offsetting the discomfort caused by the wearing of the anti-exposure suit or heat created by cockpit equipment and resulting high-temperature ambient air. The vent-air system for the F-18 aircraft supplies temperature controlled and pressure regulated air to the pilot’s vent suit from the air cycle air-conditioning system. COMPONENTS The vent-air system components include a vent suit temperature valve and sensors, a regulating and a relief valve, and a vent suit air hose assembly. Vent Suit Temperature Valve The vent suit temperature valve is normally closed, pneumatically actuated, torque motor controlled, dual poppet valve, which mixes warm and cold air. The location of the valve is shown in figure 5-16, item A. The vent suit temperature valve torque motor regulates muscle pressure to control hot and cold airflow. The ACS temperature/flow controller controls the torque motor. The torque motor control in this valve can be overridden by a vent suit over temperature sensor, which vents muscle pressure to close the valve if an over temperature condition exists. Vent Suit Temperature Sensor The temperature sensor is located in a manifold downstream of the vent suit temperature valve (fig. 5-16, item B). The sensor sends signals to the ACS temperature/flow controller. Vent Suit Over-Temperature Sensor The over-temperature sensor is a pneumatic bleed-off sensor, located in a manifold downstream of the vent suit temperature valve (fig. 5-16, item C). If manifold temperature reaches 120°±15°F, the sensor vents muscle pressure from the vent suit temperature valve, causing the valve to close. Vent Suit Pressure Regulating Valve The valve is located downstream of the sensor manifold and limits flow rate of 14 cubic feet per minute (cfm) at a pressure of 3 psi above cabin pressure. The flow rate can be manually reduced below maximum by use of the manual flow control on the vent suit air hose assembly. Vent Suit Pressure Relief Valve The pressure relief valve is a tube assembly containing an integral spring-loaded poppet valve, which prevents rupture of the vent suit air hose assembly by a failed vent suit pressure regulator. The 5-15 Figure 5-16.—Vent suit system component locator.

pressure relief valve begins to open at 10 psi and is fully open at 18 psi. Vent Suit Air Hose Assembly The air hose assembly located on the left console is made up of a manual flow control and a vent suit disconnect. The manual flow control allows the pilot to manually regulate airflow entering the vent suit through the vent suit disconnect. OPERATION The F-18 vent suit system operates when the air cycle air-conditioning system is on. Vent suit system operation is switched from automatic to manual when the environmental control system (ECS) MODE switch on the ECS panel assembly (fig. 5-17) is set from AUTO to MAN. Automatic Mode When the ECS MODE switch is in AUTO position, the ACS temperature/flow controller modulates the vent suit temperature control valve as required to maintain a constant temperature in the vent suit sensor manifold. The vent suit temperature sensor signals the controller if manifold temperature changes and the controller makes torque motor current adjustments to the temperature valve accordingly. In this mode, the temperature selected on the SUIT TEMP control is maintained without manual adjustments. Manual Mode When the ECS MODE switch is in MAN position, the ACS temperature/flow controller adjusts and holds the vent suit temperature valve torque motor in position determined by the SUIT TEMP control knob. In this mode, input from the vent suit temperature sensor is not used by the ACS temperature/flow controller and SUIT TEMP control may have to be adjusted periodically to maintain desired temperature. Also, in this mode the vent suit system can be operated in a wider temperature range. Q5-23. A vent-air system is used for what purpose? Q5-24. Where is the vent suit temperature sensor located? Q5-25. Identify the six major components of a vent-air system. Q5-26. What are the two modes of operation for a vent-air system? RADAR LIQUID COOLING SYSTEM LEARNING OBJECTIVE : Describe the radar liquid cooling system and its compo- nents. The F-18 aircraft radar liquid cooling system (fig. 5-18) circulates liquid coolant to remove heat from the radar transmitter high-voltage RF energy modules. Coolant heated by the transmitter is routed through a closed loop system to a heat exchanger. The heat exchanger converts heated coolant to cooling air. A temperature control valve is integral to the heat exchanger to maintain a minimum coolant temperature level. One of the three sources of air is induced across the heat exchanger to provide coolant temperature control. During normal flight operations, ram air is induced across the heat exchanger by an electrically powered ram air scoop. At high ram air temperature conditions (hot day-low altitude or high speed-high altitude), the ram air scoop is closed by a signal from the air data computer (ADC), and conditioned air from the ACS is delivered to the heat exchanger. For ground operation, with aircraft weight on wheels, a cooling fan supplies cooling air to the heat exchanger. When cooling air is supplied from the ACS, a coolant temperature sensor operates through the 5-16 Figure 5-17.—ECS panel assembly, ECS MODE switch suit/cabin temp control.

temperature/flow controller to modulate an airflow valve and limit preconditioned air to the heat exchanger. The coolant is filtered and the system monitored for filter contamination, ram air door actuator position, low pressure, high temperature, and coolant quantity. COMPONENTS Components of the radar liquid cooling system include a cooling liquid-to-air heat exchanger, a liquid coolant pump, an airflow valve, a ground cooling fan, a filter, a low-pressure sensor, and temperature sensors. Cooling Liquid-to-Air Heat Exchanger The liquid-to-air heat exchanger (fig. 5-19, item A) extracts heat from the liquid coolant that flows through the two pass counter flow channels within the heat exchanger. A single-pass air circuit dissipates heat extracted by the heat exchanger. A thermostatic temperature control valve is mounted in the inlet/outlet manifold of the heat exchanger, and senses coolant temperature. The control valve mixes bypass and core fluid to maintain a delivery temperature of 80° to 90°F to the radar transmitter. In the cold position (bypass valve fully closed), a bleed flow of 0.05 to 0.10 gallons per minute (gpm) is provided to aid in purging the core during system servicing. Liquid Coolant Pump The liquid coolant pump (fig. 5-19, item B) assembly is a self-priming, submerged, centrifugal pump with a cylindrical two-section reservoir and a fill level gauging mechanism. Air bleeding of the reservoir is done by manually actuating a bleed valve connected to the reservoir. The gauging mechanism in the pump unit combines inputs from coolant temperature and reservoir piston position to change a fluid level indicator on the service panel and produces a signal to the digital display indicator (DDI) to display a low fluid maintenance code. 5-17 Figure 5-18.—Radar liquid cooling system. Figure 5-19.—Radar liquid cooling system component locator.

Airflow Valve The airflow valve (fig. 5-20, item A) is pneumatically modulated to limit, as necessary, conditioned air to the radar liquid cooling liquid-to-air heat exchanger. The ACS temperature/flow controller supplies electrical power to the airflow valve torque motor, which opens or closes muscle pressure to the airflow valve. The airflow valve is spring-loaded closed, and a built-in test is monitored by the ACS temperature/flow controller. If the airflow valve fails, the ACS temperature/flow controller produces a signal to produce a faulty maintenance code in the DDI. Ground Cooling Fan The ground cooling fan (fig. 5-19, item C) is electrically powered and supplies a flow of ambient air for heat transfer from the liquid cooling heat exchanger during aircraft ground operations. Coolant System Filter Coolant is filtered before passing through the radar transmitter. When the replaceable filter element (fig. 5-21, item A) is contaminated, resulting differential pressure will extend a manually reset indicator on the filter assembly, providing a visual contamination indication. Low-Pressure Sensor The low-pressure sensor (fig. 5-20, item B), located in the coolant line, provides a ground to the maintenance status display and recording system until the coolant pressure falls below presets limits. The loss of ground causes a weapon system fail code in the DDI. High-Temperature Sensor The coolant high-temperature sensor (fig. 5-20, item C), located in the coolant line, provides a ground to the maintenance status display and recording system until coolant temperature rises above preset limits. The loss of ground causes a weapon system fail code in the DDI. Coolant Temperature Sensor The coolant temperature sensor (fig. 5-21, item B), located in the coolant line, provides coolant tempera- ture reading to the ACS temperature/flow controller, allowing the controller to modulate the airflow valve. Q5-27. Describe the purpose of the F-18 aircraft radar liquid cooling system. Q5-28. During ground operation, what component supplies cooling air for the heat exchanger? Q5-29. Name the eight major components of the radar liquid cooling system. Q5-30. Describe the operation of the ground cooling fan. FIRE-EXTINGUISHING SYSTEM LEARNING OBJECTIVES : Describe a fire-extinguishing system and its components. Identify an auxiliary power unit fire detection and extinguishing system. 5-18 Figure 5-20.—Radar liquid cooling system component locator. Figure 5-21.—Radar liquid cooling system component locator.

CF 3 BR (the chemical symbol for triflourobromomethane) is a fluorinated hydrocarbon. It is the most common extinguishing agent used in aircraft fire-extinguishing systems. It is a more efficient extinguishing system than CO 2, and under normal atmo- spheric pressure and temperature, it is an odorless and tasteless gas. CF 3BR exists as a liquid only when contained under pressure. CF 3BR is nontoxic, non-corrosive, leaves no residue, does not deteriorate with age, is an electrical insulator, and goes farther than CO 2. NOTE:C F3BR is very volatile. It is nontoxic, but a danger of suffocation exists because, like carbon dioxide, CF 3BR replaces oxygen when breathed. Among the many fire-extinguishing agents, only CF 3BR will be discussed in this chapter. The P-3 aircraft uses a typical CF3BR fire-extinguishing system. The P-3 fire-extinguishing system (fig. 5-22) controls fires within the engines and nacelles and is equipped with two similar independent electrically controlled fire-extinguishing systems, no. 1 and no. 2. One system is used for fire extinguishing in no. 1 and no. 2 engines and nacelles. The second system is used for no. 3 and no. 4 engines and nacelles. Both systems are electrically controlled from the flight station. Each system utilizes two fire-extinguishing system container and valve assemblies located in the inboard nacelles. The fire-extinguishing system container and valve assemblies are accessible through the main landing gear wheel wells and an access door on the power plant firewall. A pressure gage mounted on each container is visible under a hinged access door on the firewall. Each container is pressurized to 600 (+25, –0) psi and charged with 10.5 (+25, –0) pounds of fire-extinguishing agent. A chart with a minimum pressure versus container temperature curve is shown in table 5-1. There are no plumbing interconnections between the two fire-extinguishing systems, no. 1 (left wing, 5-19 Figure 5-22.—P-3 Engine fire extinguishing system. NOTE Pressures listed are minimum for known temperature of container to ensure proper operation of the system. Ambient temperature may be used to determine container temperature, if at least 4 hours have elapsed since last engine operation. If pressure gauge reads in excess of 100 psig above minimum, container must be removed not later than next phased inspection. A pressure reading of 50 psig maximum below chart pressure is acceptable for container use. CONTAINER TEMPERATURE °C –51 –40 –29 –18 –7 –1 5 10 16 21 27 32 38 43 49 51 60 65 °F –60 –40 20 0 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Table 5-1.—Engine and APU Fire Extinguisher Container and Valve Assembly Minimum Pressure Versus Temperature

no. 1 and no. 2 engine nacelles) or no. 2 (right wing, no. 3 and no. 4 engine nacelles). Each system has only two containers; one container for each engine or two containers for the same engine. Either system is no longer effective for fire extinguishing after the two containers in the system have been discharged. The two main plumbing lines from each container for a system are connected to transfer check valves and then to outlets in the engine fire zones. Installed in the plumbing between container and transfer check valve is a test plug. COMPONENTS Fire-extinguishing system components include transfer check valves, drain valves, check valves, and a container assembly. Transfer Check Valve A transfer check valve (fig. 5-23, item A) has two inlet ports and one outlet port, and a poppet that shuts off one inlet port. Therefore, only one inlet port is utilized for the direct position, and the other inlet port is used for transfer position. There is no restriction on the outlet port. Drain Valves Drain valves (fig. 5-23, item B) are provided in the plumbing immediately forward and aft of each transfer check valve, and when the tubing is routed from an inboard engine to the wing front beam. A drain valve constructed in the same manner as a check valve is spring-loaded to the open position to drain any condensation at the low points in the system plumbing. When a container is discharged, pressure of the agent overcomes the spring force and closes the drain valve, allowing all agents to go to the engine outlets. As pressure is relieved in the tubing, the drain valve opens under spring force. Check Valve Each engine nacelle zone has one fire-extinguishing outlet. The outlets for zones 1 and 2 incorporate a check valve (discharge nozzle) (fig. 5-23, item C) installed at the end of the plumbing outlet. Zone 3 has an unrestricted outlet. Container Assembly The container (fig. 5-24) is a welded steel sphere approximately 9 inches in diameter, and is cadmium 5-20 Figure 5-23.—Engine fire extinguishing system schematic diagram.

plated for corrosion prevention. The internal volume of the container is 400 (+20, -15) cubic inches. The container is filled with 10.5 (+0.25, -0.00) pounds of fire-extinguishing agent and pressurized with nitrogen to 600 (+25, -0) psi. Total weight of the charge is 10.81 to 11.22 pounds including 0.47 pounds of nitrogen. A mounting bracket, which is welded to the container, attaches to the forward face of the firewall and protrudes through the aft side of the firewall. Each container is equipped with two valve assemblies to discharge a container; however, only one assembly is fired at any one time to discharge a container. Each valve assembly contains a high-temperature electrically controlled dual squib cartridge with a slug attached. OPERATION When a fire-extinguishing discharge switch is actuated to complete the circuit, the cartridge is electrically fired to allow its slug to rupture the frangible disc in the neck of a container. A screen adjacent to the disc retains the six frangible disc segments when the cartridge is fired. The extinguishing agent is expelled from the container. A safety disc plug is installed inside the overboard discharge port and has a burst range of 1450 to 1800 psi at 200°F. There are eight circuit breakers used in the engine fire-extinguishing system. These circuit breakers are located at the forward load center and supply 28 Vdc, when a closed electrical path has been provided through the discharge switch to ignite the cartridges in the fire-extinguishing container and valve assembly. Four emergency shutdown handles and four fire-extinguishing discharge switches arm and dis- charge the system. Normally, a discharge switch is not actuated until the respective emergency shutdown handle for that engine has been pulled aft. A protective guard around the switch prevents inadvertent actuation of the discharge button although the switch can be pushed. With an engine fire indicated by the fire warning lights on the fire-extinguishing control panel, the respective and individual emergency engine shutdown handle is pulled aft approximately 6 inches to gain access to the discharge switch for the engine nacelle indicating the fire. As a specific example, if a fire is indicated in no. 3 engine nacelle, pull no. 3 engine emergency handle aft and press the no. 3 engine fire-extinguishing discharge button. If the fire persists and it becomes necessary to discharge the second container of the same fire-extinguishing system into no. 3 engine nacelle, the transfer switch, which is guarded and shear-wired in the DIRECT TO ENGINES position, must be set to TRANSFER TO ADJACENT ENGINES, and the no. 3 engine fire-extinguishing discharge button must be pressed again. This action electrically ignites the cartridge in the transfer container valve assembly of the second fire-extinguishing container in that system. The rate of discharge of a fire-extinguishing system is approximately 0.4 seconds. All containers, distribu- tion lines, nozzles, and fittings are of stainless steel. AUXILIARY POWER UNIT (APU) FIRE DETECTION AND EXTINGUISHING SYSTEM The APU compartment fire detection and extinguishing system provides automatic fire control on the ground and in flight. The automatic system is backed up by audible and visual warnings and manual release of the extinguishing agent. The warning light and MAN REL AUX PWR UNIT EXTINGUISHER switch are located adjacent to the no. 4 nacelle discharge switch on the glareshield APU FIRE W ARNING AND EXTINGUISHER panel. In addition to the flight station warning horn, another identical horn is located at the main load center, which is 5-21 Figure 5-24.—Fire extinguishing system container and valve assembly.

operable on the ground only. The automatic ex- tinguisher system is a dual channel system energized from the detector signal. The primary channel fires a dual cartridge squib by means of a limit switch that actuates when the APU exhaust door is fully closed (approximately 15 seconds is required for exhaust door closure). If the primary channel fails to operate, the secondary channel, through a time delay relay, fires the cartridge in approximately 20 seconds. The glareshield-mounted MAN REL AUX PWR UNIT EXTINGUISHER switch may be used to energize both fire extinguisher channels and thus bypass the detector system. In addition to operating the warning light, horns, and extinguisher automatic discharge, the detector system also provides output signals to accomplish complete electrical shutdown of the APU. This includes intake and exhaust door closure, fuel valves closed, fuel pumps off, and ignition circuit deenergized. The fire detector is armed from the aircraft ac-dc distribution system at all times that the aircraft generator or ground power is available. In the absence of ac power, the detector is armed from the aircraft battery. The detector is disarmed when the battery is disconnected. A maintenance switch accessible through an access door may disarm the detector and the extinguisher functions. Closure of the access door rearms the system. An APU TEST switch is mounted adjacent to the four nacelle test switches on the overhead panel in the cockpit. Upon setting the APU TEST switch, the fire warning lights will come on and the horn will sound, indicating the system is working properly. Q5-31. Under normal atmospheric pressure and temperature, describe the characteristics of CF 3BR. Q5-32. How many independent fire-extinguishing systems does a P-3 aircraft use? Q5-33. List the different ports for a transfer check valve. Q5-34. What is the internal volume of a P-3 fire-extinguishing container? Q5-35. Describe the procedures if a fire is indicated in no. 3 engine nacelle. Q5-36. Describe the purpose of an auxiliary power unit. Q5-37. What is/are the indication(s) given if a fire is present in the APU? 5-22 Figure 5-25.—Waveguide pressurization system.

W A VEGUIDE PRESSURIZATION SYSTEM LEARNING OBJECTIVE : Identify the waveguide pressurization system and its com- ponents. The purpose of the F-18 waveguide pressurization system (fig. 5-25) is to contain and transport the regulated, filtered, dry air to the radar and electronic countermeasures (ECM) waveguide cavities. COMPONENTS The waveguide pressurization system is made up of a filter, two pressure regulating valves, two desiccators, two ground test ports and tubing. Avionics Pressurization Filter Assembly The avionics pressurization filter assembly (fig. 5-26, item A) in the nose wheelwell is made up of a filter element and a relief valve. During normal operation, regulated muscle pressure from the flow/temperature limiting anti-ice modulating valve (windshield anti-ice/rain removal system) passes through the filter element, which removes 100 percent of particles larger than 25 microns and 98 percent of particles larger than 10 microns. When the filter element is contaminated, a pressure differential of 4 to 5 psi will open a relief valve and bypass air around the filter element without interrupting system operation. Waveguide Fluid Pressure Regulating Valve The ECM (fig. 5-26, item B) and radar (fig. 5-26, item C) waveguide pressure regulating valves are located in the nose wheelwell and function identically. One is for the ECM waveguide and the other is for the radar waveguide. These waveguide fluid pressure regulating valves receive filtered muscle pressure airflow and regulate this airflow from 0.3 to 4.3 pounds per square inch absolute (psia) outlet pressure. Each waveguide fluid pressure regulating valve has two aneroid assemblies to regulate air pressure. Primary aneroid assembly force is balanced against spring force through an orifice on which a ball is seated. An auxiliary aneroid assembly functions as an added adjustment and as a trigger assembly to allow internal pressure relief to atmosphere if regulated pressure exceeds 4.3 psia. A resettable indicator is visible when an overpressure condition has occurred. A check valve next to the outlet port of the waveguide fluid pressure regulating valve closes to maintain waveguide pressure during an overpressure condition. 5-23 Figure 5-26.—Waveguide pressurization system component locator.

Air Desiccators There are two waveguide air desiccators in the system. One is for ECM (fig. 5-26, item D) and one is for radar (fig. 5-27). They are located downstream from the waveguide fluid pressure regulating valves. The waveguide air desiccators contain a blue desiccant and silica gel material, which absorbs moisture as airflow passes through the waveguide air desiccators. When the desiccant and silica gel material becomes saturated with moisture, the material color changes from blue to pink. The silica gel is visible through a moisture indicator port on the housing of the waveguide air desiccators. Test Ports The waveguide pressurization system has two test ports: one for ECM and one for radar. The test ports are located downstream from the regulators and are used as gauge connection points when testing system pressure. OPERATION The waveguide pressurization system provides regulated, filtered dry air to the ECM and radar waveguide cavities. The waveguide fluid pressure regulating valves controls this air pressure. Each waveguide fluid pressure regulating valve has an indicator that pops out and vents downstream pressure in excess of 4.3 psia. The indicator remains popped until manually reset. The system functions automatically whenever source air pressure (muscle pressure) is on. Q5-38. What is the purpose of an F-18 waveguide pressurization system? Q5-39. What percentage of particles will the filter assembly remove if they are 25 microns or larger? Q5-40. The waveguide pressure regulating valve has how many aneroid assemblies to regulate air pressure? MISSILE LIQUID COOLING SYSTEM LEARNING OBJECTIVE : Identify the operating principles and maintenance safety precautions for the missile liquid cooling utility system. The missile liquid cooling system in the F-14 aircraft provides thermal conditioning for the radar system of the weapon control system (WCS) and missile. The temperature control system consists of a WCS cooling loop for the radar system and a missile cooling loop for the missile system; both loops are controlled by a common controller. In each loop, a motor-driven pump circulates a dielectric coolant fluid. The fluid is filtered to remove air, moisture, and foreign matter. The right Phoenix missile fairing (fig. 5-28) contains the missile coolant pump assembly and the missile-air-moisture contaminant remover. When the missile cooling loop is not required, the fairing is removed from the aircraft. The ultimate heat sink is ram air and/or refrigeration system air for cooling; hot air from the bleed manifold 400°F temperature control system provides heating. The WCS/missile temperature control system also uses cooling air from the ground cooling system when ground operation is required. COMPONENTS Components of the missile liquid cooling system include a cold and a hot air modulating valve, an air-to-coolant heat exchanger, a coolant pump, a coolant fluid expansion tank, a bypass valve, an air-moisture-contaminant remover, a missile controller, a coolant temperature sensor, a fairing interlock switch, and a liquid cooling control panel. Missile Cold Air Modulating Valve The cold air modulating valve (fig. 5-29) is mounted on the air-to-coolant heat exchanger. The 5-24 Figure 5-27.—Radar air desiccator.

5-25 Figure 5-28.—Missile fairing. Figure 5-29.—Missile cooling system component locator.

valves modulate the flow of refrigeration system air to their respective heat exchanger section in response to electrical signal from the WCS/missile controller. The valve has a butterfly, a diaphragm-type pneumatic actuator that is mechanically linked to the butterfly, an electro-magnetic torque motor, and butterfly position switches. Electrical signals from the missile controller govern the torque motor, which allows regulated air pressure to be vented. The smaller the amount of air pressure vented, the larger the valve opening. If the electrical power of air pressure is interrupted, the valve closes. Missile Hot Air Modulating Valve The missile hot air modulating valve (fig. 5-29) is mounted on the air-to-coolant heat exchanger. The valve modulates the flow of hot air from the 400°F bleed manifold temperature control system in response to electrical signals from the controller. The hot air heats the coolant during system warm-up. The operation of the valve is the same as the missile cold air-modulating valve. Missile Air-to-Coolant Heat Exchanger The air-to-coolant heat exchanger (fig. 5-29) consists of two sections: weapons control system (radar) loop, and missile loop. The heat exchanger is similar to an automobile radiator. The coolant flows though the core while air flows around the core. When the radar portion of the heat exchanger is being used, the missile cold and hot air modulating valves are closed to prevent reverse flow through the missile section. Missile Coolant Pump The coolant pump (fig. 5-30) is a single-stage, centrifugal pump driven by a low-slip, two-pole induction motor. When the pump is operating, it circulates 18 gallons of coolant per minute through the system. The pump is lubricated and cooled by a small portion of the coolant, which is circulated through the motor. A pressure switch in the pump outlet opens when the pump output pressure drops to 60 ±5 psi. The pressure switch causes the MSL COND (missile 5-26 Figure 5-30.—Missile cooling system component locator.

condition) advisory light to illuminate. Also, a thermal switch will open when 230° ±5°F is reached. This switch causes the pump to stop and also illuminates the MSL COND light. The coolant pump is located in the right Phoenix fairing. Coolant Fluid Expansion Tank The expansion tank (fig. 5-30) is located in the right Phoenix fairing. The tank maintains a constant coolant fluid pressure at the pump inlet, accommodates thermal expansion of the coolant, and provides a coolant reserve for the missile loop in case of leakage. The tank has a bellows, fluid sight and level indicator, fluid relief valve, and a pneumatic pressure indicator. The bellows is pressurized to maintain a positive fluid pressure of 30 to 70 psi at the pump inlet. Should pressurization reach 45 ±2.3 psi, the fluid pressure relief valve will open and vent fluid. The fluid sight and level indicator displays fluid level, and the pneumatic pressure indicator extends to indicate air pressure by tem- perature degrees. Missile Bypass Valve The missile bypass valve is used to bypass the missile when the fluid pressure within the missile reaches 89 +0, -5 psi. When the condition exists, the bypass valve opens. This allows a portion of the coolant fluid to flow from the supply line to the return line without passing through the missile. Missile Air-Moisture-Contaminant Remover The remover (fig. 5-30) is mounted in the right Phoenix fairing. It removes air, moisture, and foreign particles from the coolant, but it does not remove standing water. The remover consists of a cleanable filter element, a replaceable removal cartridge, a fail-safe valve and indicator, a relief valve, and an automatic shutoff valve. If the removal cartridge fails, the fail-safe valve prevents coolant loss by securing the air-water removal overboard port. If this occurs, a yellow indicator button is released to warn of cartridge failure. If the pressure drop across the filter element exceeds 16 ±3 psi, the red differential pressure indicator button extends to warn of a clogged filter. If the pressure drop exceeds 21 to 25 psi, the relief valve passes coolant around the filter element. When the filter bowl is removed, an automatic shutoff valve closes to prevent loss of coolant. Missile Controller The controller (fig. 5-30) is the brain of the liquid cooling system. It receives electrical input from the sensors and controls component operation. It keeps the hot and cold modulating valves from opening at the same time. The controller also provides electrical signals to the naval flight officer (NFO) caution advisory indicator. Coolant Temperature Sensor Two sensors are located in the cooling loop. The sensors are isolated from the coolant by being installed in wells that are filled with thermal grease. Both sensors are identical in construction, but each has a different purpose in the system. One sensor is mounted in the missile return line. The other sensor is in the missile supply line of the missile loop. Each sensor contains two sensing elements. One performs the primary sensing function, and the other is used for the built-in test (BIT). Fairing Interlock Switch The fairing interlock switch provides an electrical connection for the missile coolant pump motor and pressure switch circuits. The switch is closed when the Phoenix fairing is installed. Liquid Cooling Control Panel The liquid cooling control panel is located on the NFO’s left side console. When the liquid coolant switch is set to the AWG-9/AIM-54 position, it activates both the radar and missile cooling loops of the system. 5-27

The functional relationship of the components is represented in figure 5-31. OPERATION Setting the LIQ COOLING (liquid cooling) switch to the AWG-9/AIM-54 position starts the missile coolant pump motor. The pump circulates 8 gallons of coolant per minute through the missile air-moisture-contaminant remover, the missile section of the WCS/missile air-to-coolant heat exchanger, the weapons rails, left and right pylon, missile launchers, and through as many as six Phoenix missiles. The heat absorbed by the coolant from the missiles is removed in the air-to-coolant heat exchanger. When the loop is operating in the cooling mode, the missile inlet coolant temperature sensor controls the fluid temperature at 70° ±3°F by opening or closing the cold air modulating valve. The valve varies the amount of cold air flowing from the refrigeration system through the missile heat exchanger. When the temperature of the coolant fluid returning from the missile is below 40° ±3°F, as sensed by the missile outlet coolant temperature sensor, the cooling system automatically switches to the warm-up mode. In this mode, the cold air modulating valve closes and the hot air modulating valve opens. This valve varies the amount of hot air from the 400°F bleed manifold tem- perature control system used to warm the coolant fluid. When the heat exchanger outlet fluid temperature reaches 104° ±4°F and the missile outlet fluid temperature reaches 85° ±3°F, the hot air modulating valve will close. This prevents the cold and hot modulating valves from being open simultaneously. The missile supply line sensor, located at the outlet of the heat exchanger, is also used to sense an over-temperature condition. If the coolant temperature exceeds 115° ±3°F, the missile condition (MSL COND) advisory indicator light illuminates. The hot or cold air-modulating valve will close. If the missile pump pressure drops to 60 ±5 psi, a pressure switch causes the MSL COND light to illuminate. If coolant pressure downstream of the coolant pump increases to 89 ±5 psi, the missile bypass valve opens to return the fluid to the pump inlet. 5-28 Figure 5-31.—Missile cooling system.

MAINTENANCE SAFETY PRECAUTIONS The Phoenix missile requires a completely contaminant-free cooling system. Keeping the system clean requires the use of toxic fluids that must be used with special care. It is important to handle this system with the same care as you would handle an oxygen system. The following information is of special interest and should be kept in mind when working on this system. • If more than 1 gallon of coolant is required to fill the expansion tank, you should flush and refill the system, using the liquid coolant service unit (LCSU). For detailed LCSU operating procedures, you should refer to the applicable MIM. • The cooling system should only be serviced with Flo-cool 180, Coolanol 25, or Coolanol 25-R. If you use another type of coolant, you may damage the missile components. It is a requirement that you wear a respirator or work in an area with forced ventilation while working with these coolants. Additionally, you must wear chemical splash-proof goggles and gloves. • When you use trichlorotrifluoroethane, MIL-C-81302, type I or II, to clean fittings and hoses, exercise extreme caution. You must wear a respirator and chemical splash-proof goggles and gloves. The task should be performed in an area with forced ventilation. Smoking is prohibited in the area where the chemical is being handled. Keep trichlorotrifluoroethane from coming in contact with your skin, eyes, and clothes. Do not breathe the toxic vapors. • To prevent contamination of the temperature control system and possible damage to its components, absolute cleanliness of your equipment, work area, and coolant must be maintained. You should ensure the dust caps, flushing jumpers, hoses, and bleed lines are thoroughly cleaned with trichlorotrifluoroethane and lint free cloth. The cleaned components should be air dried before installation. Do not allow O-ring seals to soak in cleaning fluid before or after cleaning because this will cause hardening of the O-rings and premature failure. • When adding coolant with the fluid make-up unit, add the coolant slowly. Rapid pumping may cause the pressure relief valves on the make-up and in the aircraft to open. • Coolant spilled on the aircraft can damage the paint. Spillage should be wiped up immediately. Spillage on a coaxial cable may cause the cable to come apart. • To take a coolant sample, the coolant must have been circulated for at least 5 minutes by the aircraft powered pump. This circulation ensures that the sample will be representative of coolant in the entire system. The sample should be taken from the AIM-54 supply bleed port. Q5-41. Describe the purpose of the missile liquid cooling system. Q5-42. What is the purpose of the missile hot air modulating valve? Q5-43. The coolant pump circulates what amount of coolant per minute? Q5-44. What type of protective measures must you take when servicing the missile liquid cooling system? Q5-45. Prior to taking a coolant sample, the coolant must have circulated for what amount of time? 5-29

CHAPTER 5 ANSWERS TO REVIEW QUESTIONS A5-1. Air-conditioning, pressurization systems, electronic cooling, windshield wash- ing, anti-icing, and anti-g systems A5-2. 125 psi A5-3. Consists of four loops of bleed air leak sensing elements located close to the auxiliary power unit, bleed air ducts, and an engine start port leak detector located near the engine ground start port A5-4. In normal operation, when the temperature of a section or short segment of the sensing element exceeds 255°F , the chemical in the tube conducts electric current, which completes a transformer circuit to ground similar to the test relay. The indicator light on the annunciator panel will come on to indicate the loop is overheating. A5-5. Bleed air leak detector control, bleed air leak sensing elements, and an engine start port leak detector A5-6. Two A5-7. An anti-icing system is designed to prevent ice from forming on the aircraft. A deicing system is designed to remove ice after it has formed. A5-8. Electrical heaters, hot air, or a combination of both A5-9. Shutoff valves, modulating valves, thermostats, and leading edge skin tem- perature indicator and overheat circuit caution light circuit A5-10. When the bleed air valve is open 2 degrees or more A5-11. To provide airflow over the external surface of the windshield for rain removal and windshield anti-icing A5-12. Warm air temperature control valve, warm air temperature sensor, flow/temperature limiting anti-ice modulating valve, warm air over-temperature sensor, anti-ice/rain removal air control regulating valve, windshield overheat temperature sensor, and windshield anti-ice/rain removal switch A5-13. Warm air temperature control valve A5-14. WINDSHIELD ANTI-ICE/RAIN removal switch A5-15. 50 percent water-methyl alcohol mixture A5-16. Solenoid-operated valve A5-17. The relief valve inside the windshield-washing shutoff valve opens and pressure in the tank is reduced. A5-18. 1 1/2 gallons A5-19. Reduces the fatiguing effect of repeated exposure to positive or negative g-forces, also provides a method by which the crewmember can relieve fatigue and physical tension during extended flight A5-20. Anti-g valve, anti-g system filter, and quick disconnects 5-30

A5-21. 10 psi A5-22. As high-g conditions occur, the anti-g valves activating weight is forced down to close the exhaust valve and open the demand valve. This allows cooled engine bleed air from the refrigeration system service heat exchanger to flow through the anti-g valve, where it is regulated, to inflate the g-suit. Pressure to the g-suit is varied in proportion to the g-force acting upon the aircraft and crewmembers, to a maximum of 10 psi. As g-forces decrease, the activating weight is forced upward by spring tension. This reduces the pressure of the airflow to the g-suit and exhausts excess suit pressure into the cabin. As this occurs, the demand valve closes, blocking air from the g-suit. A5-23. Provides a measure of personal comfort, offsetting the discomfort caused by the wearing of the anti-exposure suit or heat created by cockpit equipment and resulting high-temperature ambient air A5-24. In a manifold downstream of the vent suit temperature valve A5-25. Vent suit temperature valve, over-temperature sensor, pressure regulating valve, pressure relief valve, and air hose assembly A5-26. Automatic and manual A5-27. Circulates liquid coolant to remove heat from the radar transmitter high-voltage RF energy modules A5-28. Ground cooling fan A5-29. Cooling liquid-to-air heat exchanger, liquid coolant pump, airflow valve, ground cooling fan, coolant system filter, low-pressure sensor, high-temperature sensor, and coolant temperature sensor A5-30. The ground cooling fan is electrically powered and supplies a flow of ambient air for heat transfer from the liquid cooling heat exchanger during aircraft ground operations. A5-31. It is a more efficient extinguishing system than CO 2, and under normal atmospheric pressure and temperature, it is odorless and tasteless. A5-32. Two A5-33. Two inlet ports and one outlet port, and a poppet that shuts off one inlet port A5-34. 400 (+20, -15) cubic inches A5-35. If a fire is indicated in no. 3 engine nacelle, pull no. 3 engine emergency handle aft and press the no. 3 engine fire-extinguishing discharge button. If the fire persists and it becomes necessary to discharge the second container of the same fire-extinguishing system into no. 3 engine nacelle, the transfer switch, which is guarded and shear-wired in the DIRECT TO ENGINES position, must be set to TRANSFER TO ADJACENT ENGINES, and the no. 3 engine fire-extinguishing discharge button must be pressed again. This action electrically ignites the cartridge in the transfer container valve assembly of the second fire-extinguishing container in that system. A5-36. Provides detection and extinguishing for the APU compartment on the ground and in flight A5-37. A horn sounds and a warning light illuminates A5-38. To contain and transport the regulated, filtered, dry air to the radar and electronic countermeasures (ECM) waveguide cavities 5-31

A5-39. 100 percent A5-40. Two A5-41. To provide thermal conditioning for the radar system of the WCS and missile A5-42. The valve heats the coolant during system warm-up A5-43. 18 gallons A5-44. Respirator or an area with forced ventilation, and chemical splash-proof goggles and gloves A5-45. 5 minutes 5-32

CHAPTER 6 AIR-CONDITIONING AND PRESSURIZATION SYSTEMS The combined pressurization system and air-conditioning of the cabin is the function of the aircraft pressurization and air-conditioning system, now in all naval aircraft. The inspection and maintenance of this system is one of the important duties of the AME. EARTH’S ATMOSPHERE LEARNING OBJECTIVE : Recognize the effect high-altitude flight could have on flight personnel because of decreased atmospheric pressure. Transferring a human being from their natural environment on the Earth’s surface to the environment at 40,000 feet places them in surroundings in which they cannot survive without artificial aids. Even at half that altitude, breathing becomes very rapid, and above 25,000 feet, unconsciousness occurs, quickly followed by death. A brief study of Earth’s atmosphere tells us why this condition exists. The envelope of atmosphere surrounding the Earth is a gaseous mixture consisting chiefly of nitrogen and oxygen. There are traces of other gases, but they have no significance as far as body functions are concerned. Chemical analysis has shown that the proportions of nitrogen and oxygen are constant throughout the thickness of the atmosphere, up through 200,000 feet or more. ATMOSPHERIC PRESSURE Although the chemical content of the atmosphere remains fairly constant, the density (mass per unit volume) of the atmosphere varies with altitude. At 18,000 feet, the density is about one-half of the density at sea level, and at 36,000 feet, it is only about one-fourth of the density at sea level. The atmospheric pressure also varies with altitude. The pressure exerted by the atmosphere may be compared to the pressure of a column of water. If holes are made in the container of the column, the force with which the water spurts out of the upper holes will be considerably less than that at the bottom of the column. Similarly, the pressure exerted by the atmosphere is much greater near the surface of the Earth than it is at high altitudes. For example, the pressure of the atmosphere at sea level is 14.7 pounds per square inch (psi), while the pressure at 40,000 feet above sea level is 2.72 psi, and at 60,000 feet is 1 psi. As an aircraft ascends to higher altitude, the resulting decrease in atmospheric pressure may affect flight personnel in several ways. The most noticeable effect is in breathing. Breathing is a mechanical process that depends heavily on atmospheric pressure. When a person inhales, they automatically raise their ribs and depress their diaphragm so that the chest cavity is enlarged. This reduces the air pressure within the cavity below that of the atmosphere outside. Air is thus pushed into the lungs. When they exhale, they reduce the chest cavity, increasing the pressure within it. This pushes the air out of the lungs. When low atmospheric pressures are encountered, the lungs are not filled so completely when inhaling. With lower density, a person gets fewer molecules of air in each breath. If they get fewer molecules of air in each breath, they also get fewer molecules of oxygen, and no person can live unless they get a sufficient amount of oxygen. This problem may be solved up to certain altitudes by the proper use of oxygen equipment; however, at extremely high altitudes (above 35,000 feet), the atmospheric pressure is so low that the pressure of the blood and other liquids in the body are no longer balanced. The human body then tends to burst. In some cases, blood vessels near the surface may burst, causing hemorrhages in the ears, eyes, and breathing passages. The outside air temperature also changes with altitude. For example, at approximately 18,000 feet, the outside air temperature will be –4°F (–20°C), and at approximately 37,000 feet the outside air temperature will be –67°F (–55°C). Above 37,000 feet, the air continues to thin, but the air temperature will remain constant for several miles and then begin to rise slowly. Thus, the lowest outside air temperature to be encountered by an aircraft could occur at a height of about 7 miles. 6-1

TYPES OF OXYGEN Aviators breathing oxygen (ABO) (MIL-0-27210) is supplied in two types—type I and type II. Type I is gaseous oxygen and type II is liquid oxygen. Oxygen procured under this specification is required to be 99.5 percent pure. The water vapor content must not be more than 0.02 milligrams per liter when tested at 21.1°C (70°F) and at sea level pressure. Technical oxygen, both gaseous and liquid, is procured under specification BB-O-925A. The moisture content of technical oxygen is not as rigidly controlled as is breathing oxygen; therefore, the technical grade should never be used in aircraft oxygen systems. The extremely low moisture content required of breathing oxygen is not to avoid physical injury to the body, but to ensure proper operation of the oxygen system. Air containing a high percentage of moisture can be breathed indefinitely without any serious ill effects. The moisture affects the aircraft oxygen system in the small orifices and passages in the regulator. Freezing temperatures can clog the system with ice and prevent oxygen from reaching the user. Therefore, extreme precautions must be taken to safeguard against the hazards of water vapor in oxygen systems. CHARACTERISTICS OF OXYGEN Oxygen in its natural state is a colorless, odorless, and tasteless gas. Oxygen is considered to be the most important of all the elements to life. It forms about 21 percent of the atmosphere by volume and 23 percent by weight. The remainder of the atmosphere consists of nitrogen (78 percent) and inert gases (1 percent), of which argon is the most abundant. Of all the elements in our environment, oxygen is the most plentiful. It makes up nearly one-half of the Earth’s crust and approximately one-fifth of the air we breath. Oxygen combines with most of the other elements. The combining of an element with oxygen is called oxidation. Combustion is simply rapid oxidation. In almost all oxidations, heat is given off. In combustion, the heat is given off so rapidly it does not have time to be carried away; the temperature rises extremely high, and a flame appears. Some examples of slow oxidation are rusting of iron, drying of paints, and the change of alcohol into vinegar. Even fuels in storage slowly oxidize, the heat usually being rapidly carried away. However, when the heat cannot easily escape, the temperature will rise and a fire may break out. This fire is the result of spontaneous combustion. Oxygen does not burn, but it does support combustion. Nitrogen neither burns nor supports combustion. Therefore, combustible materials burn more readily and vigorously in oxygen than in air, since air is composed of about 78 percent nitrogen by volume and only about 21 percent oxygen. In addition to existing as a gas, oxygen can exist as a liquid and as a solid. Liquid oxygen is pale blue in color. It flows like water, and weighs 9.52 pounds per gallon. EFFECTS OF LACK OF OXYGEN A decrease in the amount of oxygen per unit volume of air results in an insufficient amount of oxygen entering the bloodstream. The body reacts to this condition rapidly. This deficit in oxygen is called hypoxia. When the body regains its normal oxygen supply, one may recover from hypoxia. A complete lack of oxygen, which results in permanent physical damage or death, is called anoxia. Hypoxia There is an enormous increase in oxygen requirements caused by an increase in physical activity. Strenuous exercise like long distance running greatly increases the need for oxygen, which is evidenced by deep and rapid breathing. Even mild exercise like getting up and walking around a room may double the air intake. In the case of the aviator, leaking of an oxygen mask, which may go completely unnoticed while the wearer is at rest, may lead to collapse and unconsciousness when an attempt is made to move from one station to another in the aircraft. A walkaround (portable) oxygen bottle that is sufficient for 24 minutes of quiet breathing may be emptied by 17 minutes of use when the user is moving around inside the aircraft. Effects of Hypoxia People differ in their reactions to hunger, thirst, and other sensations. An individual’s reactions vary from time to time under similar circumstances. Illness, pain, fear, excessive heat or cold, and many other factors govern what the response will be in each particular case. The same thing is true of individual reactions to oxygen starvation. The effects of hypoxia on a given 7-2

person cannot be predicted accurately. For example, a person may be relatively unaffected one day, but highly susceptible the next. It is difficult to detect hypoxia, because its victims are seldom able to judge how seriously they are affected, or if they are affected at all. The unpleasant sensations experienced in suffocation are absent in the case of hypoxia. Blurring of vision, slight shortness of breath, a vague weak feeling, and a little dizziness are the only warnings. Even these may be absent or so slight as to go unnoticed. While still conscious, the aviator may lose all sense of time and spend the last moments of consciousness in some apparently meaningless activity. In such a condition, a person is a menace to the crew as well as to himself. Since the aviator understands that it is the reduced air pressure at higher altitudes that determines the effect on the body, dependence should be upon the altimeter rather than sensations or judgment to determine when oxygen is needed. The effects of hypoxia at various altitudes are discussed in the following paragraphs. BELOW 10,000 FEET.—At or below 10,000 feet, some effects of hypoxia may be present. Generally, the eye is the first part of the body to suffer effects of hypoxia. Even at a relatively low altitude of approximately 5,000 feet, where no other effect of hypoxia can be detected, night vision may be affected, due to mild oxygen starvation. Thus, the use of supplemental oxygen on night flights above 5,000 feet is required. Although hypoxia affects the eyes in the daytime as well as at night, the results during the day are usually not as noticeable below 10,000 feet. BETWEEN 10,000 AND 15,000 FEET .— Although efficiency may be considered impaired at 10,000 to 15,000 feet, death from oxygen starvation at these altitudes is virtually unknown. The greatest dangers are from errors in judgment or performance due to drowsiness or mental confusion. At these altitudes, long flights without oxygen produce persistent drowsiness and excessive fatigue for many hours afterward. Frequently, persistent headaches develop soon after completion of the flight. For these reasons, the use of oxygen on flights above 10,000 feet is required. Portable oxygen systems are available for aircraft that do not have oxygen equipment. BETWEEN 15,000 AND 20,000 FEET.—Flights at 15,000 to 20,000 feet, even for short periods, must never be attempted without the use of oxygen. Collapse and unconsciousness are common. Failure to use oxygen could result in death, especially when the situation is complicated by loss of blood in combat or by shock due to pain or fear. BETWEEN 20,000 AND 25,000 FEET.—During World War II, most military flying was done in unpressurized aircraft at altitudes of between 20,000 and 25,000 feet. Most of the resulting anoxia deaths occurred in this altitude range. The general symptoms of drowsiness, mental confusion, dim vision, and dizziness occur here, as at lower altitudes, but they come on much more quickly, allowing less opportunity for corrective action. Consequently, under no cir- cumstances should aircraft ascend to these altitudes, even for short periods, without the use of oxygen by all persons aboard. The movement of personnel in the aircraft requires the constant use of walk-around equipment. Unusual actions or failure of a crewmember to respond quickly and clearly when called require immediate investigation. BETWEEN 25,000 AND 30,000 FEET .— Between 25,000 and 30,000 feet, collapse, un- consciousness, and death quickly follow interruption of the oxygen supply. Mask leakage at these altitudes may cause a degree of hypoxia that, although not noticed during flight, can produce considerable fatigue and have serious cumulative effects. ABOVE 30,000 FEET .—Above 30,000 feet, unconsciousness and death strike rapidly and often without warning. At such altitudes, it is imperative that all oxygen equipment is functioning correctly and that each breath is taken through a properly fitted oxygen mask. Above a pressure altitude of 35,000 feet, pressure breathing oxygen equipment is required. Q7-1. As an aircraft climbs, what effect occurs to the volume of air? Q7-2. Unless an aviator breathes additional oxy- gen, which three main systems on the body begin to fail? Q7-3. Above 33,000 feet to approximately 35,000 feet, oxygen equipment provides what per- centage of oxygen? Q7-4. Above 43,000 feet, what requirement is the only adequate provision for the safety of an aviator? Q7-5. Oxygen procured under MIL-0-27210 is required to be what minimum percent pure? Q7-6. What color is liquid oxygen? Q7-7. A complete lack of oxygen is referred to by what medical term? 7-3

GASEOUS OXYGEN SYSTEMS LEARNING OBJECTIVE : Identify safety precautions, components, and maintenance procedures for gaseous oxygen systems. Gaseous oxygen systems are used primarily in large, multi-place aircraft where space and weight limitation are less important items and the systems are used only occasionally. HANDLING/SAFETY PRECAUTIONS The pressure in gaseous oxygen supply cylinders should not be allowed to fall below 50 pounds per square inch (psi). If the pressure falls much below this value, moisture is likely to accumulate in the cylinder and could be introduced into the oxygen system of the aircraft, causing component malfunction. All oxygen under pressure is potentially very dangerous if handled carelessly. Personnel servicing or maintaining oxygen systems and components must be extremely careful about preventing grease, oil, hydraulic fluid, or similar hydrocarbons as well as other contamination from coming in contact with lines, hoses, fittings, and equipment, as this contact presents a fire and explosion hazard. If, because of hydraulic leaks or some other unpreventable malfunction, components of the oxygen system do become externally contaminated, they should be cleaned using only approved oxygen system cleaning compounds. While some MIMs specify the use of a variety of cleaning compounds, the preferred compound is oxygen system cleaning compound type I conforming to Military Specification MIL-C-81302. The following safety precautions should be adhered to: • Under no circumstances should a non-approved cleaning compound be used on any oxygen lines, fittings, or components. • When handling oxygen cylinders, the valve protection cap should always be in place. Before removing the cap and opening the valve, ensure that the cylinder is firmly supported. A broken valve may cause a pressurized cylinder to be propelled like a rocket. • Do NOT use oxygen in systems intended for other gases or as a substitute for compressed air. • Cylinders being stored for use on gaseous oxygen servicing trailers or any other use must always be properly secured. Do not handle cylinders or any other oxygen equipment with greasy hands, gloves, or other greasy materials. The storage area should be located so that oil or grease from other equipment cannot be accidentally splashed or spilled on the cylinders. Additional safety precautions may be found in the publications of technical manual NAVAIROSH Requirements for the Shore Establishments , NA V AIR A1-NAOSH-SAF-000/P-5100; Aviators Breathing Oxygen (ABO) Surveillance Program Laboratory Manual and Field Guide, A6-3332AO-GYD-000; and Aviator Crew Systems Technical Manuals , NA V AIR 13-1-6.4 series. SYSTEM COMPONENTS Basically, all gaseous oxygen systems consist of the following: • Containers (cylinders) for storing oxygen supply • Tubing to route the oxygen from the main supply to the users • Various valves for directing the oxygen through the proper tubing • Metering devices (regulators) to control the flow of oxygen to the user • Gauges for indicating the oxygen pressure • Masks to direct the oxygen to each user’s respiratory system Cylinders Gaseous oxygen cylinders used in naval air- craft systems are generally high-pressure and non-shatterable, meaning that the cylinder is designed to resist shattering when punctured by a foreign object, such as gunfire, at a pressure of 1,800 psi. The resistance to shattering is generally achieved by the use of a heat-treated alloy or wire wrapping applied to the outside of the cylinder. The two most common cylinder sizes are 514 and 295 cubic inches. The main advantage of the high-pressure cylinder is that it minimizes space used for storing gaseous oxygen. All high-pressure oxygen cylinders are painted green in accordance with the established color codes provided in MIL-STD-101A. Cylinders come equipped with either a manually operated handwheel valve or an automatic self-opening 7-4

valve (figs. 7-1 and 7-2). Opening the handwheel operated valve assembly releases the contents of the cylinder. The handwheel has four 5/15-inch diameter holes for the attachment of remote operation equipment, if needed. The valve is equipped with a fusible metal safety plug and a safety disc to release the contents of the cylinder if the pressure becomes excessive because of high temperature. The safety plug is filled with a fusible metal designed to melt at temperatures ranging from 208°F to 220°F (97.8°C to 104.5°C). The cylinder and valve assembly is connected to the oxygen tubing by soldering the tubing to a coupling nose and securing the nose to the valve outlet with a coupling nut. The self-opening (automatic) oxygen cylinder valve is automatically opened when it is connected to the oxygen line. The use of this type of valve permits remote location of the oxygen cylinder to places less vulnerable during combat and more readily accessible for servicing. Regulators The success or failure of high-altitude flight depends primarily on the proper functioning of the oxygen breathing regulator. Acting as a metering device, the regulator is the heart of the oxygen system. To perform successfully in an aircraft system, a regulator must deliver the life-supporting oxygen in the quantities demanded throughout its entire range of operation. Although personnel of the Aircrew Survival Equipmentman (PR) rating are primarily responsible for maintenance of regulators, the AME is responsible for performing operational checks in the aircraft and for removal and installation. In other words, the AME removes a malfunctioning regulator from the aircraft and delivers it to the shop where the PR determines the trouble and makes the necessary repairs. When the trouble is corrected, the AME reinstalls the regulator in the aircraft. Tubing Two types of tubing are used in aircraft oxygen systems. Low-pressure aluminum alloy tubing is used in lines carrying pressures up to 450 psi. High-pressure 7-5 1. CYLINDER 2. LABEL–INSTRUCTION ON W ALTER KIDDE CYLINDERS 3. HANDGRIPS 4. HANDWHEEL 5. NUT, HANDWHEEL 6. W ASHER, LOCK EXTENSION TEETH, BRONZE, NO. 10 7. CAPS, V ALVE 8. STEM, UPPER 9. DIAPHRAGM (SET OF 3) 10. BUSHING 11. GASKET, BUSHING 12. CAP, SPINDLE 13. SPRING 14. SEAT, V ALVE 15. PLUG, SAFETY 16. DISC, SAFETY 17. W ASHER, SAFETY DISC 18. CAP, OUTLET 19. W ASHER, OUTLET CAP 20. BODY, V ALVE 21. NUT, COUPLING 22. NOSE, COUPLING Figure 7-1.—Gaseous oxygen cylinder and handwheel valve assembly. 1. SELF-OPENING HIGH-PRESSURE OXYGEN V ALVE ASSEMBLY 2. SAFETY PLUG ASSEMBLY 3. SAFETY DISC 4. DISC W ASHER 5. SPRING NEST 6. SPRING 7. ASSEMBLY CHECK Figure 7-2.—Self-opening oxygen cylinder valve.

copper or aluminum alloy tubing is used in lines carrying pressure above 450 psi. Lines running from the filler valve to each of the cylinders are called filler lines. Those running from the cylinders to the regulators are called distribution or supply lines. Oxygen lines, like all other lines in the aircraft, are identified by strips of colored tape. The strips of tape are wrapped around each line near each fitting and at least once in each compartment through which the line runs. The color code for oxygen lines is green and white with the words Breathing Oxygen printed in the green portion, while black outlines of rectangles appear in the white portion. Resistance to fatigue failure is an important factor in oxygen line design because the line pressure in a high-pressure system will at times exceed 1,800 psi, and at other times be as low as 300 psi. Because of these varying pressures and temperature, expansion and contraction occur all the time. These fluctuations cause metal fatigue, which must be guarded against in both the design and the construction specifications for tubing. Steps are taken during installation to prevent fatigue failure of the tubing. Tubing is bent in smooth coils wherever it is connected to an inflexible object, like a cylinder or a regulator. Every precaution is taken to prevent the accidental discharge of compressed oxygen because of faulty tubing or installation. Although simple in construction and purpose, tubing is the primary means by which oxygen is routed from the cylinders to the regulator stations. High-pressure tubing is used between the oxygen cylinder valve and the filler connection in all systems, between the cylinder valve and the regulator inlet in high-pressure systems, and between the cylinder valve and pressure reducer in reduced high-pressure systems. To connect high-pressure copper tubing, adapters and fittings are silver-soldered to the tubing ends. Due to the high pressures involved, the security (leak tightness) of all high-pressure lines relies primarily on a metal-to-metal contact of all its fitting and connections. A fitting properly silver-soldered to the end of a length of copper tubing will not come loose or leak. Valves Various types of valves are installed in gaseous oxygen systems. Among the most commonly used are check valves, pressure-reducing valves, and filler valves. CHECK V ALVES.—Check valves are installed at various points in the oxygen system. Their purpose is to permit the flow of oxygen in one direction only and to prevent the loss of the entire oxygen supply in the event a cylinder or line is ruptured. Various styles of single, dual, and triple check valves are available, as shown in figure 7-3. The arrows embossed on the valve casting indicates the direction of flow through the valve. PRESSURE-REDUCING V ALVES .— Pressure-reducing valves (or pressure reducers) are used in certain oxygen systems for the purpose of reducing high cylinder pressure to a working low pressure. In most installations the pressure reducers are designed to reduce the pressure from 1,800 psi to a working pressure of 60 to 70 psi. They are always located in the oxygen distribution lines between the cylinders and the flight station outlets. Figure 7-4 illustrates a typical pressure-reducing valve. FILLER V ALVES.—All oxygen systems are designed so the entire system can be serviced (refilled) through a common filler valve. The filler valve is 7-6 Figure 7-3.—Oxygen system check valves.

generally located so it may be reached by a person standing on the ground or wing. The filler valve contains a check valve, which opens during the filling operation and closes when filling is completed. A dust cap keeps out dust, dirt, grease, and moisture. Gauges Gauges are used in gaseous oxygen systems to indicate the oxygen pressure in pounds per square inch. All systems are equipped with at least one gauge that indicates the amount of oxygen in the cylinders. The gauge also indicates indirectly how much longer the oxygen will last. The volume of any gas compressed in a cylinder is directly proportional to the pressure. If the pressure is half, the volume is half, etc. Therefore, if 900 psi of oxygen remains in a 1,800-psi system, half the oxygen is left. A pressure gauge is always mounted at each flight station, usually on the regulator. These gauges are calibrated to indicate from 0 to 2,000 psi on high-pressure systems and 0 to 500 psi on reduced high-pressure systems. TYPICAL GASEOUS OXYGEN SYSTEMS As previously stated, naval aircraft equipped with high-pressure oxygen systems are designed for approximately 1,800 psi, with working pressures reduced to 60 to 70 psi by a reducer or regulator. Systems equipped with a pressure reducer are referred to as reduced high-pressure systems. The reduced high-pressure gaseous oxygen system shown in figure 7-5 is typical of high-pressure cylinders and supplies three regulators—one each for the pilot, copilot, and flight engineer. 7-7 Figure 7-4.—Pressure-reducing valve. Figure 7-5.—Reduced high-pressure oxygen system schematic.

SYSTEM OPERATION The pressure manifold, which is equipped with internal check valves, receives oxygen flow from the cylinders, directs the flow into a common line, and routes it to the pressure reducer. The manifold assembly also connects to a filler line, allowing the three cylinders to be recharged simultaneously from an external supply. The pressure reducer decreases the pressure to 65 psi. Incorporated on the low-pressure side of the pressure reducer is a relief valve, which connects through tubing to an overboard discharge indicator. In the event of excessive pressure developing within the low-pressure section of the pressure reducer, the excess pressure will flow through the relief valve and out the overboard discharge line. This flow will rupture the green disc in the discharge indicator, giving a visual indication of a malfunctioning pressure reducer. A line from the high-pressure side of the pressure reducer connects to a gauge in the cockpit. This gauge gives the pilot an indication of pressure in the three storage cylinders. Portable Oxygen Systems Portable oxygen systems include walkaround cylinders, survival kits, and bailout units. These systems are used primarily to maintain crew functions in the event of failure of the fixed oxygen systems. The survival kit oxygen system also performs the same function during descent after bailout. All of these are small, lightweight, high-pressure, self-contained gaseous systems, which are readily removed from the aircraft. Walkaround cylinders are standard equipment on many transport, patrol, and early warning aircraft, and are used separately or in addition to a permanently installed oxygen system. Each system consists of a reducer and regulator assembly mounted directly on a small oxygen cylinder. Figure 7-6 illustrates a high-pressure walkaround oxygen system. It is a 295- or 514-cubic-inch capacity, 1,800-psi cylinder equipped with a regulator, which is connected to the cylinder with a short coiled length of copper tubing. A short flexible breathing tube, clamped to the outlet of the regulator at one end and fitted with a connector at the other end, provides the assembly for the attachment of the demand mask tube. Straps fastened to the cylinder bracket provide the means for securing the unit to the user’s seat or part of the aircraft’s structure. The cylinder bracket may be placed horizontally or stood on end while in use. The straps can be used as a handle to carry it from place to place. Because of its weight, the walkaround unit should not be carried by its breathing tube, regulator, or copper tubing. SYSTEM MAINTENANCE The maintenance procedures discussed in this section are general in nature. Consult the applicable MIM prior to performing any maintenance on each specific type of aircraft. Routine maintenance includes servicing of cylinders, checking the system and regulators for leaks, operationally checking the system, and troubleshooting malfunctions. 7-8 Figure 7-6.—Portable oxygen system.

Malfunctions may become apparent during inspections, testing, or actual use of the oxygen system. The remedies for some malfunctions will be quite obvious, while in other cases it may require ex- tensive time and effort to pinpoint the actual cause. The effectiveness of corrective action will be dependent on an accurate diagnosis of the mal- function. Troubleshooting of the gaseous oxygen system, as with the other systems, is the process of locating a malfunctioning component or unit in a system or mechanism. To troubleshoot intelligently, you must be familiar with the system and know the function of each component within the system. You can study the schematic diagrams of the system provided in the MIM to gain a mental picture of the location of each component in relation to other components. By learning to interpret these diagrams, you can save time in isolating malfunctioning components. The schematic diagram does not indicate the location of components in the aircraft; however, it will provide the means to trace the oxygen flow from the cylinder through each component to the mask. Installation diagrams provided in either the MIM or the illustrated parts breakdown (IPB) will assist you in locating the particular component in the aircraft. The MIMs provide a variety of troubleshooting charts, which are intended to aid you in discovering the cause of malfunction and its remedy. Table 7-1 illustrates one type of chart. The discrepancy is listed in the first column with the probable cause in the second and the remedy in the third. The list of probable causes is arranged in the order of probability of occurrence. Q7-8. The pressure in gaseous oxygen supply cylinders should not be allowed to fall below what level? Q7-9. What is the preferred compound for use in oxygen system cleaning? Q7-10. True or False. Oxygen systems can be used as a substitute for compressed air. Q7-11. What component is used to direct the oxygen to the user’s respiratory system? Q7-12. What are the two most common cylinder sizes? 7-9 Discrepancy Probable Cause Remedy Excessive leakage of system pressure. Filler valve leaking. Replace filler valve. Leak in lines. Check tubing, fittings, and connections and repair or replace as necessary. Flexible hose leaking. Replace hose. Regulator not shut off. Shut off regulator. Crewmember receives insufficient oxygen at high altitude. Improperly functioning regulator. Replace regulator. Ill-fitting mask. Refit or replace mask. Mask flapper valve not operating properly. Check mask exhaust valve. Flexible tubing to mask crushed or kinked. Replace tubing as necessary. No pressure reading at the regulator Defective regulator. Replace regulator. Oxygen supply turned off. Turn on cylinder hand valve if so equipped. System not charged. Replenish oxygen supply. Regulator pressure gauge indications are incorrect. Gauge defective. Replace gauge. Regulator flow indicator not functioning. Indicator defective. Replace regulator. Table 7-1.—Gaseous Oxygen System Troubleshooting

Q7-13. High-pressure copper or aluminum alloy tubing can withstand what amount of pressure? Q7-14. What is the purpose of oxygen check valves? LIQUID OXYGEN (LOX) SYSTEMS LEARNING OBJECTIVE : Identify safety precautions, components, installation and testing of components, and operating proce- dures for liquid oxygen (LOX) systems. Liquid oxygen, commonly referred to as LOX,i s normally obtained by a combined cooling and pressurization process. When the temperature of gaseous oxygen is lowered to –182°F under 720 psi pressure, it will begin to form into a liquid. When the temperature is lowered to –297°F, it will remain a liquid under normal atmospheric pressure. Once converted into a liquid, oxygen will remain in its liquid state as long as the temperature is maintained below –297°F. The liquid has an expansion ratio of about 862 to 1, which means that one volume of LOX will expand about 862 times when converted to a gas at atmospheric pressure. Thus, 1 liter of LOX produces about 862 liters of gaseous oxygen. SAFETY PRECAUTIONS As already mentioned, the main dangers of LOX are the extremely low temperature of the liquid, its expansion ratio, and its support of violent combustion. The liquid is nontoxic, but will freeze (burn) the skin severely upon contact. Use extreme caution not to touch implements containing LOX unless gloves are worn. Without gloves, bare skin would immediately stick and freeze to the metal surface. Personnel who could be exposed to accidental spillage of LOX must wear a face shield, coveralls, gloves, and oxygen safety shoes to prevent skin and vision damage. Open gloves, low-cut shoes, trousers with cuffs, and similar improper clothing that can form pockets capable of holding a quantity of LOX present a severe hazard. All personnel handling LOX must wear the protective clothing specified in the protective clothing section of NA V AIR 13-1-6.4. A greater danger than freezing is the combustion-supporting potential of oxygen. When LOX is used, it is possible to build up high concentrations of oxygen quickly. Many materials such as cloth, wood, grease, oil, paint, or tar will burn violently when saturated with oxygen, provided an ignition source is supplied. A static electric discharge or spark can serve as an igniter. Once an oxygen-enriched fire is started, it is virtually impossible to extinguish until the oxygen supply is cut off. An added danger exists if a combustible material is saturated with oxygen at low temperatures. Many materials, especially hydrocarbons, tar, etc., will burn with explosive violence when saturated or subjected to very mild shock or impact. Extreme care must be taken not to splash or spill LOX on clothing. When LOX comes in contact with cloth, an ideal and deadly situation for a fire exists—a fire that cannot be put out. LOX by itself will not burn, but mixing with the smallest amount of almost any material will cause the liquid to boil and splash violently, making combustion possible. If splashed out of a container, LOX will break into many parts upon contact with the floor/deck. It must be poured slowly from one container to another to avoid splashing, and to allow the gaining receptacle to cool sufficiently without thermal breakage. NEVER seal or cap the vent port of a liquid oxygen system, because liquid oxygen at atmospheric pressure will generate up to 12,000 pounds of pressure if allowed to evaporate in a sealed container or system that has no relief provisions. Access to oxygen supply/storage areas should be limited only to personnel familiar with proper handling procedures. The area should be adequately ventilated and free of any materials that could present a fire hazard. All pressure-type containers, plumbing, and pressure-relief devices should conform to the applicable maintenance manual and be kept in good repair. The vents on LOX containers are designed to have a sufficient flow capacity to carry away any oxygen that may boil off in case of accidental loss of insulation. Do NOT cap such vents or cause the opening to be restricted in any way. The pressure relief assembly in LOX system storage cylinders consists of a reseatable relief valve and rupture disc in parallel. The assembly is designed so that the relief valve relieves first, with the rupture disc acting as a safety backup in the event the relief valve malfunctions or its relieving capacity is exceeded. 7-10

LOX converters and servicing trailers should be stowed or parked so that they are protected from excessive heat and direct rays of sunlight as much as is practical. All LOX should be segregated from containers of other gases or liquids and all flammable materials. Hydrocarbons such as oil and grease in the oxygen handling area could result in death, serious injury, and property damage. Smoking, open flames, or sparks are not permitted in any oxygen handling area. When transferring oxygen, provide adequate ventilation to prevent the formation of an oxygen-enriched atmosphere. Avoid spilling LOX on floors or deck areas. In case of accidental spillage, ventilate the area. Intentional draining of LOX from a system or container must be caught in a clean drain pan and allowed to evaporate in a suitable open area that will not present a hazard. In the event that LOX is spilled on clothing, separate clothing from skin contact immediately and thoroughly air clothing for 1 hour to allow dilution of the oxygen concentration. When an uninsulated container of LOX is touched or when there is any reason to suspect some part of the body has been frozen or chilled, the area should be thoroughly washed or immersed in clean water that is slightly above body temperature (approximately 104°F to 113°F). The exposed area should then be loosely wrapped with a clean, dry dressing, and medical aid should be sought immediately. When servicing and maintaining LOX systems, the AME will be required to transfer LOX from servicing trailers to aircraft converters, and occasionally from the converter to the drain pan. The AME also will be required to remove and install converters and other components of LOX systems. All servicing and maintenance of LOX systems must be done in accordance with instructions contained in the applicable aircraft MIM. All safety precautions concerning the handling of LOX must be adhered to. When a completely empty system is being serviced, the LOX should be added slowly to cool the converter down to the storage temperature (–297°F). The converter could otherwise be damaged by thermal shock or rapid pressure buildup. Additional gaseous and liquid oxygen safety precautions and handling procedures are provided in the following publications: • NA V AIR A1-NAOSH-SAF-000/P5100/1, NAVAIROSH Requirements for the Shore Establishment • NA V AIR 06-30-501, Technical Manual of Oxygen/Nitrogen Cryogenic Systems All personnel handling oxygen and maintaining gaseous or liquid oxygen systems should be thoroughly familiar with all precautions and procedures listed in the latest revisions to these publications. They also should be familiar with the specific precautions provided in the applicable aircraft MIM and those pertaining to the type of equipment being used to service such systems. SYSTEM COMPONENTS Aircraft LOX systems are similar to gaseous oxygen systems except that the several cylinders of gaseous oxygen are replaced by one or more LOX converters. The use of more than one converter provides for an adequate supply of oxygen on long-range flights or where there is more than one crewmember using the oxygen systems. In addition to the converters, most LOX systems contain a heat exchanger; filler, pressure control, relief, and shutoff valves; quick-disconnect couplings; low-pressure switch; oxygen lines and regulators; and quantity indicating units. See figure 7-7 for a schematic diagram of a LOX system. 7-11 Figure 7-7.—LOX system schematic.

Container The LOX converter (fig. 7-8) consists of an inner and outer shell of stainless steel separated by a vacuum. A blowout disc provides a margin of safety from explosion if a leak occurs in the inner shell. Filler Valve The filler valve is a combination filler, vent, and buildup valve. The filler portion of the valve is essentially a spring-loaded check valve (fig. 7-9). When the servicing hose of the LOX cart is coupled to the filler connection, the poppet is displaced. This seals the supply port and allows container pressure to be relieved through the vent port. At the same time, oxygen flows through the filler connection and fill port to the container. When the container is full, the liquid flows from the container through the gas port and then through the vent port. In the normal position, the spring in the filler connection holds the poppet in place, forming a gastight seal. There is a check valve in the fill port that acts as a backup seal in the event the filler connection develops a leak. The vent port also is sealed in this position, allowing the gaseous boil-off (from the top of the container) to flow through the gas port to the supply port and into the oxygen system. Pressure Control Valve The pressure control valve used on most converters is a combination opening and closing valve (two valves contained within one housing). These valves are controlled by spring-loaded bellows. The pressure-closing valve is spring-loaded open and the pressure-opening valve is spring-loaded closed. The pressure-opening valve controls the flow of gaseous oxygen into the supply line. If the pilot’s demand for oxygen becomes greater than the capability of the pressure opening valve to deliver, there is a differential check valve that opens and allows liquid oxygen to flow directly into the supply line. It is transformed into gaseous oxygen during its passage through the oxygen system supply lines. Relief Valves A relief valve is provided in the converter to relieve excessive pressure buildup in the event of a malfunction in the pressure control valves. It also relieves normal pressure buildup when the system is not in use. This normal buildup pressure is caused by heat entering the system, and will cause a loss of 10 percent of the system’s capacity every 24 hours; for example, approximately 1 liter of loss will be experienced from a 10-liter converter. Quick-Disconnect Couplings Liquid oxygen systems are designed for the rapid removal of the LOX converter for ease of servicing and maintenance. This is accomplished by the use of supply and vent quick-disconnect couplings, a single point converter retainer wing nut hold down, and 7-12 Figure 7-8.—Liquid oxygen converter assembly. Figure 7-9.—Filler valve.

quick-disconnect quantity indicator lead disconnects (fig. 7-10). The vent and supply quick-disconnect couplings are of two-piece construction. The male half is mounted on the LOX converter, and the female half is attached to the flexible oxygen supply and vent lines. The coupling for the supply line contains a spring-loaded check valve, which closes automatically when the supply line is uncoupled from the converter. This prevents contaminating the aircraft oxygen system when the converter is removed for servicing. The vent coupling has no check valve; however, it forms a positive seal between the vent port of the converter and overboard vent line. Heat Exchanger The lungs would be damaged if gaseous oxygen were breathed at the temperature at which it exits the LOX converter. The purpose of the air-to-oxygen heat exchanger is to increase the temperature of the gaseous oxygen after it leaves the LOX converter. The heat exchanger is located in the cockpit area of the aircraft to expose it to a temperature capable of warming the gaseous oxygen regardless of the altitude of the aircraft. The heat exchanger is aluminum with a large interior surface area (fig. 7-11). Low-Pressure Switch The low-pressure switch is located in the oxygen supply line. It indicates to the flight crew, through a caution light in the aircraft cabin, when system pressure falls below minimum operating pressure of the system. This alerts and allows the pilot to descend to a safe altitude. Quantity Indicating System The quantity indicating system consists of a quantity gauge and a warning light in the cockpit. A quantity probe is also a part of the liquid oxygen converter. This probe senses the amount (quantity) of liquid in the converter. This information is transmitted to the quantity gauge by an electrical coaxial cable. The quantity gauge is marked in liters from zero to the system’s maximum storage capacity (0 to 10). The gauge constantly shows the remaining liquid in the converter. The low-quantity warning light is also connected to the coaxial cable and illuminates when the quantity of liquid in the converter falls below 1 liter. 7-13 Figure 7-10.—LOX converter installation. Figure 7-11.—Aircraft air-to-oxygen heat exchanger.

Oxygen Shutoff Valve The oxygen shutoff valve is installed in the system to control the flow of oxygen to the pilot or flight crew, as required. Figure 7-12 illustrates a typical manually operated two-position valve. This valve has an inlet port, outlet port, and a relief port. The pressure-relief valve is located in the inlet chamber to protect the oxygen regulator and crewmember from excessive system pressure if there is a malfunction of the liquid oxygen converter. Also, this valve relieves excessive pressure due to thermal expansion of gaseous oxygen trapped within the system when not in use. If the oxygen system incorporates a console-mounted regulator, the shutoff valve is part of the regulator. Composite Quick-Disconnect Coupling The purpose of the composite quick-disconnect coupling is to provide a single-point connection for quickly connecting and disconnecting the pilot with aircraft oxygen, anti-g, communications, and ventila- tion air services. Oxygen Lines LOX systems are classed as low-pressure systems. As such, low-pressure tubing is used in manufacture and repair of LOX lines. All low-pressure tubing used in LOX systems is aluminum alloy 5052 tubing and is non-heat treatable. It is manufactured in seamless, round lengths, and is annealed to provide greater flexibility. Aircraft oxygen systems are fitted with 5/16-, 3/8-, and 1/2-inch sizes. Low-pressure tubing also is installed from the pressure reducer outlets in reduced high-pressure oxygen systems. Oxygen Regulators Regulators used with LOX systems are either console-mounted or miniature mask-mounted. The miniature mask-mounted regulator was especially designed for use with aircraft that have ejection seats. The console-mounted regulator is normally used in large non-ejection seat-equipped multi-place aircraft such as the E-6B and P-3. MINIATURE OXYGEN BREATHING REG- ULATOR.—The miniature mask oxygen regulator, shown in a cutaway view in figure 7-13, is intended primarily for use in aircraft having a low-pressure LOX system and ejection seats. It is often referred to as a miniature mask-mounted regulator. Since it weights only 2.3 ounces and measures approximately 2 5/8-inches in length and width, it is easily mounted on the oxygen mask or user’s torso harness. It is designed so that with an inlet pressure of 40 to 120 psi, it will deliver 100-percent oxygen automatically to the user between the altitudes of 0 and 50,000 feet. Oxygen at system pressure, warmed to a comfortable temperature, flows into the regulator inlet port to the demand valve diaphragm. A small passage from the inlet line sends this pressure to the backside of the diaphragm; thus, the demand valve diaphragm is 7-14 Figure 7-12.—Oxygen shutoff valve. Figure 7-13.—Cutaway view of a miniature oxygen regulator.

pressure balanced except for the light imbalance caused by an area advantage on the backside of the diaphragm, which provides a positive sealing force. The vacuum caused by inhalation causes the sensing diaphragm to tilt downward, pushing down the demand-actuating paddle. As the paddle is forced downward, its base is lifted from a seat, which seals a second passageway from the backside of the demand valve diaphragm. Raising the paddle base allows flow from this area, which causes a pressure drop behind the demand valve diaphragm and allows inlet pressure to lift the diaphragm from its seat, and oxygen flow occurs. Safety pressure is obtained by the safety pressure spring, which deflects the sensing diaphragm, causing flow through the unit until the force created by mask pressure equals the force of the spring. This returns the sensing diaphragm to a balanced condition. Automatic pressure breathing is obtained by diverting a small volume bleed from the inlet passage to the aneroid chamber. This bleed is normally vented from the aneroid cavity past the area labeled aneroid vent. At the altitude at which pressure breathing is to begin, the lip of the aneroid comes in contact with the seat, closing off the aneroid vent and building up pressure, which reacts on the sensing diaphragm. The pressure lifts the sensing diaphragm, causing flow until the mask pressure exerts a force on the sensing diaphragm equal to the force exerted by pressure buildup in the aneroid chamber. The relief valve on the unit acts as a pilot device to open the exhalation valve of the mask. This is done by isolating the pressure pickup of the exhalation valve with the tube in the outlet port of the unit, so that only the pressure sent to it by the exhalation valve pickup tube compensates the exhalation valve. AIRCRAFT-MOUNTED OXYGEN REGULA- TORS.—The MD series regulator is being used in several multi-place naval aircraft. There are two types of regulators in this series—the MD-1 (low-pressure) (fig. 7-14) and the MD-2 (high-pressure) (fig. 7-15). The only difference found in these regulators is operat- ing pressure. The operating pressure of the MD-1 regula- tor is 50 to 500 psi. The pressure gauge reads 0 to 500 psi. The operating pressure of the MD-2 regulator is 50 to 2,000 psi. The pressure gauge reads 0 to 2,000 psi. The following controls and indicators are located on the front panel of the regulator. The small oblong-shaped window area on the left side of the panel marked FLOW indicates the flow of oxygen through the regulator by a visible blinking action. The pressure gauge is on the upper right and indicates inlet pressure to the regulator. The regulator has three control levers. A supply valve controller lever, on the lower right corner, is used to control the supply of oxygen to the regulator; a diluter control lever, on the lower center of the panel, has two positions—100% OXYGEN and NORMAL OXYGEN; an emergency pressure control lever, on the lower left of the panel, has three positions—EMERGENCY , NORMAL, and TEST MASK, and with the diluter lever in the 100% OXYGEN position, the regulator delivers 100 percent oxygen upon inhalation by the user. In the NORMAL OXYGEN position, the regulator delivers a mixture of air and oxygen with the air content decreasing until a cabin altitude of approximately 30,000 feet is reached. Above this altitude, 100 percent oxygen is delivered to the user upon inhalation. 7-15 Figure 7-14.—Aircraft panel mounted oxygen regulator, type MD-1. Figure 7-15.—Aircraft panel mounted oxygen regulator, type MD-2.

With the emergency pressure control lever in the EMERGENCY position, the regulator delivers positive oxygen pressure to the outlet at altitudes when positive pressure is not automatically delivered. In the TEST MASK position, oxygen is delivered to the mask under pressure too high to breathe and is used for checking the fit of the mask. The switch must be in the NORMAL position for normal system operation. Refer to figure 7-16 for the operation of an MD type regulator. 1. Supply oxygen entering through the oxygen inlet (1) is filtered and passes through the manifold inlet assembly into the inlet supply valve (2) and then into the first-stage reduction chamber (3) by action of the inlet supply valve control lever (24). The pressure of the flowing oxygen is registered on the oxygen supply pressure gauge. 2. The reduction chamber incorporates the first-stage relief valve assembly (4) to protect the regulator against overpressures. 3. The demand valve assembly (5) is opened when the pressure across demand outer diaphragm (6) forces the demand valve lever assembly (7) down. The pressure differential exists during the inhalation cycle of the user by creating a reduction in the pressure outlet (8). 4. Reduction in pressure at the pressure outlet is sensed in the demand diaphragm chamber (9) through the sensing port (10). 5. During periods of flow, the oxygen passes through the venturi assembly (11). At the venturi assembly, the flow of oxygen mixes with ambient air, which enters the regulator through the inlet ports (12). 7-16 1. INLET 2. INLET SUPPLY V ALVE 3. REDUCTION CHAMBER 4. RELIEF V ALVE 5. DEMAND V ALVE 6. DIAPHRAGM 7. DEMAND V ALVE LEVER 8. OUTLET 9. DEMAND DIAPHRAGM CHAMBER 10. SENSING PORT 11. VENTURI ASSEMBLY 12. INLET PORT 13. DILUTER CONTROL LEVER 14. DILUTER ANEROID 15. CHECK V ALVE 16. EMERGENCY PRESSURE CONTROL LEVER 17. TEST SPRING 18. CONTROL LEVER 19. ANEROID 20. DIAPHRAGM 21. PRESSURE BREATHER V ALVE 22. PLATE ASSEMBLY 23. RELIEF V ALVE 24. SUPPLY V ALVE CONTROL LEVER Figure 7-16.—MD regulator operational drawing.

6. The addition of ambient air to oxygen is controlled by the manual diluter control lever (13) and by the diluter aneroid assembly (14), which automatically produces a 100-percent oxygen concentration at altitudes above 32,000 feet. 7. The aneroid check valve assembly (15) prevents a flow of oxygen out through the inlet ports. 8. The emergency pressure control lever (16) applies force to the emergency pressure control test spring (17), which mechanically loads the emergency pressure diaphragm through the control lever and center assembly (18). Mechanical loading of the emergency pressure diaphragm provides positive pressure at the regulator outlet. 9. Both automatic safety pressure and pressure breathing at altitudes above 30,000 feet are provided through pneumatic actuation of the aneroid assembly (19). This function begins near 27,000 feet altitude. The force exerted on the diaphragm assembly (20) by the aneroid assembly actuates the pressure breather valve assembly (21), and the oxygen flows to the diaphragm and the plate assembly (22), which is pressure loaded by this volume of oxygen acting on the demand valve lever assembly to the extent that the positive pressure is built up at the pressure outlet as the altitude increases. 10. Additional safety is obtained through the inclusion of the second-stage relief valve assembly (23) in the regulator. TURNAROUND/PREFLIGHT/POSTFLIGHT/ TRANSFER INSPECTIONS .—These inspections are visual inspections performed in conjunction with the inspection requirements for the aircraft in which the regulators are installed. Refer to table 7-2 for assistance in troubleshooting. Visually inspect the following: • Electrical performance of the panel light • Legibility of all marking • Plastic lighting plate for cracks and dis- coloration • Low or improper reading on regulator pressure gauge • Emergency pressure control lever in NORMAL position 7-17 TROUBLE PROBABLE CAUSE REMEDY Oxygen cylinder pressure gauge fails to indicate proper pressure Defective gauge Replace regulator Blocked or leaking supply line Replace or clean supply line to regulator Low cylinder pressure Refill Defective manifold inlet assembly Replace regulator Oxygen not available at mask with proper pressure source to regulator and other than emergency setting on regulator Regulator controls improperly positioned Correct position of controls Hose to mask is kinked Straighten hose and reposition outlet Regulator not functioning properly Replace regulator Oxygen not available at mask with proper pressure source to regulator and regulator controls set at EMERGENCY Kink or other malfunction between hose and mask Replace or readjust equipment as necessary Faulty linkage from emergency pressure control lever Replace regulator Oxygen available at mask but flow is not indicated Defective blinker assembly Replace regulator Gauge pressure drops when regulator is not in use Loose or leaking connections Tighten or replace connections as necessary Defective manifold inlet assembly Replace regulator Panel light fails to light Burned out lamp Replace regulator Faulty light assembly Replace lamp Faulty electrical hookup to power source Repair electrical hookup Table 7-2.—Gaseous Oxygen System Troubleshooting

• Diluter control lever in 100% OXYGEN position • Supply valve control lever in OFF position • Regulator and surrounding area free of dirt and hydrocarbons • Delivery hose and connector for cuts, fraying, kinking, hydrocarbons, and general condition If discrepancies are found or suspected, mainte- nance control should be notified. Regulators that do not pass inspection and cannot be repaired in the aircraft are removed and replaced by ready-for-issue (RFI) regulators. Non-RFI regulators are forwarded to the nearest maintenance activity having repair capability. SYSTEM OPERATION The LOX system shown in figure 7-7 is an example of a typical system. This system converts LOX to gaseous oxygen and then delivers it to the crew. The oxygen source of this system is a supply of LOX stored in a 10-lilter converter. System pressure is maintained at 75 to 110 psi by a pressure control valve and a pressure relief valve. Through a process of controlled evaporation within the converter assembly, LOX is converted to gaseous oxygen as required by the occupant of the aircraft. The oxygen is delivered to the pilot after being warmed to a safe breathing temperature in the heat exchanger. The flow of oxygen is controlled in the cockpit by the shutoff valve. The units that make up the converter assembly control the major part of the operation of the LOX system automatically. The LOX converter has three sequences of operation—fill, buildup, and supply (fig. 7-17). In the supply sequence, the converter alternates between the economy and demand modes of operation. 7-18 Figure 7-17.—Liquid oxygen converter operation.

Fill Sequence The fill sequence begins automatically when the servicing trailer hose filler nozzle is connected to the filler port on the filler, buildup, and vent valve. The hose nozzle, when attached to the fill valve, actuates a plunger within the valve, which places the valve in the fill and vent condition (fig. 7-17, fill sequence, view A). The valve, when in this position, provides an opening from the top of the converter to the atmosphere. This opening is used to vent gaseous oxygen during filling and liquid oxygen after the converter is full. During transfer, liquid oxygen flows into the converter through a passage located in the bottom of the converter. This arrangement allows gaseous oxygen to vent through the converter top as it is being displaced by liquid flow in the bottom. When the converter is full, liquid flows overboard through the vent line, giving an indication that the converter is full. Removal of the filler hose nozzle from the fill valve automatically places the converter in the buildup sequence. Buildup Sequence The buildup sequence (fig. 7-17, buildup sequence, view B) begins when the filler hose is removed from the converter. This sequence provides for rapid pressure buildup to system operating pressure. During this sequence, LOX from the converter fills the buildup coil by gravity feed. Liquid in the coil absorbs heat from the ambient air around the coil and vaporizes, causing the pressure to build up. The gaseous oxygen formed in the coil then circulates through the pressure-closing valve and back to the top of the converter. This causes more fluid to flow into the buildup coil. This circulation continues to build up pressure until approximately 75 psi is reached. At this pressure, the pressure-closing valve is forced closed. Pressure continues to build up within the system at a slower rate, and at approximately 82 psi, the pressure-opening valve opens. When this occurs, oxygen is available at the supply outlet. A pressure relief valve, which is set at approximately 110 psi, is installed in the converter system to relieve excessive pressure. Supply Sequence The supply sequence of the liquid oxygen system consists of two modes of operation—the economy mode, in which gaseous oxygen is fed from the converter, and the demand mode, in which oxygen flows from the converter as a liquid and vaporizes to a gas in the feed line. In the economy mode of operation (fig. 7-17, supply sequence, view C), limited demand upon the system allows the converter to supply gaseous oxygen directly as a result of drawing off the gaseous oxygen stored within the top of the converter. At approximately 82 psi, the pressure-opening valve unseats and allows gaseous oxygen to flow from the converter to the supply system. Oxygen then flows from the upper (gas) portion of the converter, rather than the liquid side. When the amount of oxygen demanded by the crew exceeds the supply of the economy mode, the pressure-opening valve closes. As the crew continues to draw upon the oxygen supply, the supply system pressure becomes lower than that of the converter. When a pressure differential of 5 psi occurs, the differential check valve opens (fig. 7-17, supply sequence, views C and D) and allows liquid oxygen to flow into the supply line, creating the demand mode. Converter pressure will build up while the system is operating in the demand mode. As the pressure again approaches 82 psi, the pressure-opening valve will again unseat, switching the supply sequence back into the economy mode. The converter automatically switches itself back and forth between the economy and demand modes while supplying oxygen to the crew. SYSTEM MAINTENANCE Extreme care must be exercised when installing units in an oxygen system. The life of the pilot and crew depends on the thoroughness with which the AME does this job. All maintenance of LOX systems must be done in accordance with the instructions contained in the applicable MIM. The AME assigned to do the LOX system maintenance also should be familiar with the various instructions pertaining to handling LOX and maintenance of the related equipment. The actual removal and installation procedures used in maintaining LOX systems will vary from one aircraft to another; however, the following precautions will apply to almost any aircraft system. 1. Use only tubing assemblies that have been tested, cleaned, capped, and properly identified as oxygen lines. 7-19

CAUTION If lines are fabricated locally, ensure that only clean, oil-free tubing and fittings are used. Also, ensure that no hydraulic fluid is used in the fabrication procedure. 2. Use only the type of fittings specified for the particular oxygen system. Never use fittings with pitted or otherwise disfigured cones or imperfect threads. 3 . It is MANDATORY that EXTREME CAUTION be exercised with regard to cleanliness of hands, clothing, and tools. It must be emphasized that all items that come into contact with the oxygen system must be free of dirt, oil, or grease. 4. Use thread anti-seize tape that is approved under specification MIL-T-27730. 5. When installing tubing assemblies between fixed units, the tube assembly should align without the use of undue force. 6. The torque values specified for the particular oxygen system should be strictly adhered to when tightening the fittings. 7. If a section of line is left open or disconnected during an installation, the open fittings must be covered with suitable caps or plugs. When making connections, be certain that no lint, dust, chips, or other foreign material is allowed to enter the oxygen system. 8. Upon completion of the installation of a tube assembly or component, a pressure check of the system should be conducted. The system should be pressurized and the connections checked with a leak-test solution conforming to specification MIL-L-25567. After the connections have been checked, the leak-test solution should be washed off with clean water. 9. The aircraft liquid oxygen system should be purged after the replacement of any component or tubing assembly. 10. The type of clothing and footwear that is worn when maintaining and servicing a liquid oxygen system is an extremely important factor. Do not wear anything that will produce sparks or static electricity, such as nylon clothing or shoes with steel taps or hobnails. Oxygen-permeated clothing will burn vigorously—a most painful way to die. 11. When servicing a liquid oxygen system, en- sure that only oxygen conforming to specification MIL-0-27210 is used. Oxygen procured under Federal Specification BB-0-925A is intended for technical use and should NOT be used in aircraft oxygen systems. 12. After the completion of repairs, always perform an operational check of the system and make the required test to ensure that the oxygen is safe for use by the pilot and crew. Q7-15. When the temperature of gaseous oxygen is lowered to –182°F under 720 psi pressure, what transformation will occur? Q7-16. True or False. When working with LOX, the wearing of trousers with cuffs is authorized. Q7-17. A sealed container of LOX can generate up to what amount of pressure? Q7-18. What component on a LOX converter pro- vides a margin of safety from explosion? Q7-19. In a 24-hour period, a normal LOX system will lose what amount of pressure? Q7-20. Where is the low-pressure switch for a LOX system located? Q7-21. What are the three sequences of operation for a LOX converter? Q7-22. An aircraft liquid oxygen system should have what type of maintenance performed after replacement of any component or tubing assembly? ONBOARD OXYGEN GENERATING SYSTEM LEARNING OBJECTIVE: Identify the sys- tem components and operation of the onboard oxygen generating system. The onboard oxygen generating system (OBOGS) is an alternative to liquid oxygen. When compared to a LOX system, the OBOGS has several advantages. First, its availability may be as high as 99 percent. There are no requirements for depot-level maintenance. The OBOGS has no daily servicing requirements, and scheduled preventive maintenance occurs at 2,000 hours. Incorporation of the OBOGS eliminates the need to store and transport LOX, and it eliminates the need for LOX support equipment. The potential for accidents related to LOX and high-pressure gases is greatly reduced. 7-20

SYSTEM COMPONENTS The basic components of the OBOGS are the concentrator, oxygen monitor, and control panel assembly. Oxygen Concentrator The oxygen concentrator (fig. 7-18) produces an oxygen-rich gas by processing engine bleed air through two sieve beds. It is an electrical/mechanical device that is made up of a rotary valve, two molecular sieve beds, drive/servo motor, plenum assembly, air heater, inlet filter, over-temperature sensor indicator, pressure reducer, and insulating shroud. Oxygen Monitor The oxygen monitor (fig. 7-19) senses the partial pressure of the gas and if necessary, provides a low-pressure warning to the pilot. It is an electronic processor made up of an oxygen sensor, processing electronics, built-in test (BIT), a circuit heater, and a pressure-controlled sensing chamber. Control Panel Assembly The control panel assembly (fig. 7-20) houses the controls to operate the OBOGS system. It contains the following controls: • OBOGS ON/OFF control switch (electrical) • OXY FLOW ON/OFF control valve (mechan- ical) 7-21 Figure 7-18.—Oxygen concentrator. Figure 7-19.—Oxygen monitor. Figure 7-20.—Control panel assembly.

SYSTEM OPERATION The OBOGS, shown in figure 7-21, receives engine bleed air from the outlet of the air-conditioning heat exchanger. The partially cooled air passes through an air temperature sensor to a pressure reducer assembly. The air is then routed to the concentrator. The concentrator has a rotary valve that alternates the airflow over the molecular sieve beds. The sieve beds absorb the nitrogen and allow the oxygen and argon to pass through. Two molecular sieve beds are used in the concentrator so that while one is absorbing, the other is desorbing (releasing) nitrogen. This method allows a continuous flow of oxygen to the system. After the concentrator, the oxygen flows to a plenum assembly that acts as a surge tank and an accumulator. The plenum also functions as a heat exchanger to heat or cool the oxygen to approximately cockpit temperature. Before the oxygen reaches the oxygen regulator, the oxygen performance monitor senses the partial pressure of the gas, and provides a signal to the pilot whenever the pressure exceeds prescribed limits. The oxygen then flows through the regulator to the pilot’s mask. Q7-23. An OBOGS system availability may be as high as what percent? Q7-24. True or False. An OBOGS system has a reduced chance for potential accident. Q7-25. What are the three basic components of an OBOGS system? Q7-26. What component has a built-in test? Q7-27. During OBOGS operation, when one sieve bed is absorbing, what is the other sieve bed releasing? 7-22 Figure 7-21.—Onboard oxygen generating system (OBOGS) schematic.

CHAPTER 7 ANSWERS TO REVIEW QUESTIONS A7-1. Decreases A7-2. The eyes, brain, and muscles A7-3. 100 percent A7-4. Pressurization of the entire body A7-5. 99.5 percent A7-6. Pale blue A7-7. Anoxia A7-8. 50 psi A7-9. Type I conforming to Military Specification MIL-C-81302 A7-10. False A7-11. Mask A7-12. 514 and 295 cubic inches A7-13. Above 450 psi A7-14. To permit the flow of oxygen in one direction only A7-15. The oxygen will begin to form into a liquid A7-16. False A7-17. 12,000 pounds of pressure A7-18. Blowout disc A7-19. 10 percent A7-20. In the oxygen supply line A7-21. Fill, buildup, and supply A7-22. Purged A7-23. 99 percent A7-24. True A7-25. Concentrator, oxygen monitor, and control panel assembly A7-26. Oxygen monitor A7-27. Nitrogen 7-23

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CHAPTER 8 OXYGEN SUPPORT EQUIPMENT Oxygen systems on naval aircraft require several types of support equipment to ensure their safe and satisfactory operation. AMEs are concerned with support equipment that is used for storage and servicing of oxygen. In this chapter, storage tanks and servicing equipment are discussed. As an AME it is your responsibility to know and understand the safety precautions that are involved when working with or handling liquid or gaseous oxygen and its support equipment. This information should not stop with just the personnel of your rate, but it should be stressed to all aviation maintenance personnel, so they won’t mishandle or mistreat AME support equipment. Examples include playing with valves of service trailers, standing or sitting on trailers, hauling tools and equipment on them, spilling oils and other fluids on them, etc. Their awareness will reduce the possibility of creating hazardous conditions that could cause serious injury to themselves or others. Safety precautions also can be found in NA V AIR 06-30-501, Technical Manual of Oxygen/Nitrogen Cryogenic Systems. LIQUID OXYGEN SERVICING EQUIPMENT LEARNING OBJECTIVE : Describe liquid oxygen-servicing equipment to include safety precautions, LOX servicing trailers, and sys- tem servicing. Oxygen servicing equipment for both liquid and gaseous oxygen systems are discussed in this section. Since AMEs operate this equipment, they must be familiar with purging and sampling procedures as well as operation of the equipment while servicing aircraft oxygen systems. SAFETY PRECAUTIONS The following safety precautions must be observed when handling liquid oxygen (LOX): • Never allow LOX to contact your skin. The extremely low temperature of the liquid quickly freezes skin, and severe frostbite results. If your skin is splashed with LOX, immediately flush the area thoroughly with water, and then obtain first aid. • Always store LOX with the vent valve open. Relief valves on the tank protect the tank in case of malfunction, and are not to be used as pressure regulators. • Never confine LOX in piping or a container without adequate safety devices. When the liquid expands to a gas, the pressure buildup will rupture most piping, tubing, or containers. • Comply with all safety directives. Fifty feet away is the safe distance to permit smoking, open flames, or sparks in a LOX handling area. Assure that painting and markings on the LOX tank are maintained as required. Oxygen gas does not burn, but it vigorously supports combustion of any material that does burn. • Keep LOX away from absorbent materials, loose clothing, or rags. These materials can trap oxygen gas and later be ignited by a spark, cigarette, or match. • When LOX equipment is in use, keep it in a well-ventilated area away from all gasoline, kerosene, oil, grease, and other hydrocarbons. These substances are not compatible with LOX. Spontaneous ignition may result from contact with these substances. TMU-70/M, LOW LOSS, CLOSED LOOP LIQUID OXYGEN SERVICING TRAILER The primary purpose of portable transfer equip- ment is to provide a means of servicing oxygen systems installed in aircraft. This section will cover the TMU-70/M low loss, closed loop trailer (fig. 8-1). 8-1 Figure 8-1.—TMU-70/M low loss, closed loop, liquid oxygen servicing trailer.

During LOX servicing of aircraft converters, a lot of oxygen is lost because of the way the transfer is carried out. In addition to the economic loss, a safety hazard is created when LOX or oxygen vapors are released into the atmosphere near operating equipment and personnel. The low loss, closed loop system was designed to significantly reduce these losses and eliminate the safety hazards associated with venting oxygen in critical areas. Description The TMU-70/M is a completely self-contained unit with three major components: a 50-gallon Dewar tank, a 15-liter Dewar transfer tank, and a low loss, closed loop (LLCL) system of transfer lines. Separate liquid level and pressure gauges, as well as pressure relief devices, are provided for each tank. These components are permanently mounted on a portable three-wheel trailer, which is equipped with a manually operated parking brake and retractable caster wheel. The primary purpose of the TMU-70/M is to service aircraft LOX converters. The LLCL system is designed to recycle oxygen vapor caused by heat losses during transfer to the aircraft converter. The oxygen vapors vented from the transfer tank and aircraft converter are returned to the storage tank for cooldown and retention. Components Components include a storage tank, transfer tank, and transfer lines and piping system. STORAGE TANK .—The storage tank is a 50-gallon (U.S.) capacity, double-walled Dewar. The space between the double walls of the storage tank and transfer tank is evacuated down to 5 microns or lower and contains a multi-layer, high-vacuum insulation to minimize heat gain and boil-off of the LOX. TRANSFER TANK .—The 15-liter capacity transfer tank is a double-walled, vacuum insulated Dewar, permanently attached to the storage tank. It is self-contained and gravity-filled from the storage tank. The transfer tank is equipped with a pressure buildup coil, relief valve, rupture disc, and controls. The primary function of the transfer tank is to hold small volumes of LOX and to utilize cold gas pressure from the pressure buildup unit to transfer LOX to the aircraft converter. TRANSFER LINES AND PIPING SYS- TEM.—These lines carry the LOX from the storage tank to the transfer tank, and then to the aircraft converter. They also carry the vented oxygen gas from the aircraft’s converter to the storage tank. The closed loop system of the transfer lines contains the vented oxygen gas during filling operations. The interconnected liquid and return gas lines are vacuum-jacketed wherever practical and are a minimum length to reduce cooldown and heat leak losses. The piping system consists of a fill line for storage tank filling, a vent system for overboard venting of excess liquid or gas, and a pressure relief valve system connected to the vent system. Controls And Indicators The controls and indicators of the TMU-70/M are illustrated in figure 8-2. The functions of the controls are as follows: STORAGE TANK PRESSURE GAUGE.—(Fig. 8-2, item 1). The pressure gauge indicates the pressure in the inner storage tank. The gauge is calibrated to read from 0 to 100 pounds per square inch gauge (psig). A green band on the gauge face indicates safe operating pressure of 0 to 50 psig; a red band indicates unsafe operating pressure of 50 to 100 psig. STORAGE TANK LIQUID LEVEL GAUGE.— (Fig. 8-2, item 2). The liquid level gauge directly indicates the level of liquid oxygen in the inner tank when the tank is sitting level. The gauge dial is magnetically and mechanically coupled to a float sensor inside the storage tank. The gauge is calibrated in gallons. Safe operating levels of up to 50 gallons are indicated in green; unsafe operating levels of more than 50 gallons are indicated in red. CONVERTER VENT LINE SHUTOFF VA LV E.—(Fig. 8-2, item 3). The vent valve controls the flow of oxygen gas vapors from the converter being filled to the storage tank and prevents the loss of storage tank gas when the converter is not being filled. TRANSFER TANK VENT LINE SHUTOFF VA LV E.—(Fig. 8-2, item 4). The vent valve controls the flow of oxygen gas vapors from the transfer tank to the vapor space of the storage tank. 8-2

TRANSFER TANK FILL LINE SHUTOFF VA LV E.—(Fig. 8-2, item 5). The valve is used to control the gravity flow of liquid oxygen from the storage tank to the transfer tank. TRANSFER TANK PRESSURE BUILDUP VA LV E.—(Fig. 8-2, item 6). The pressure buildup valve controls the flow of liquid oxygen from the bottom of the transfer tank to the pressure buildup (PBU) coil. The PBU coil is a heat exchanger where the liquid oxygen is exposed to ambient temperature and is converted to gas. As the liquid changes to gas it expands. The output gas of the PBU coil is fed back to the transfer tank vapor space, providing pressure to discharge liquid to the converter. This valve is open only when pressure is required to fill the converter. TRANSFER TANK LIQUID LEVEL GAUGE.— (Fig. 8-2, item 7). The liquid level gauge indicates the level of liquid oxygen in the transfer tank. The gauge is magnetically and mechanically coupled to a float sensor inside the transfer tank. The gauge is calibrated in percent of full. TRANSFER TANK PRESSURE GAUGE .— (Fig. 8-2, item 8). The pressure gauge indicates the pressure in the transfer tank. The pressure in the transfer tank must be greater than the pressure in the storage tank to achieve transfer of liquid since the converter is vented into the storage tank during converter fill operation. The gauge is calibrated to read 0 to 160 psig. Safe operating pressure is 0 to 90 psig and is indicated by a green band; a red band indicates unsafe pressure of 90 to 160 psig. CONVERTER FULL INDICATOR GAUGE.— (Fig. 8-2, item 9). The full indicator gauge (marked LIQUID-GAS) is a vapor pressure thermometer that monitors the converter vent line temperature. During transfer of liquid to a converter, the gauge indicates GAS temperature in the converter fill line. When the converter is full, the vent line is filled with liquid oxygen overflow. The converter vent line temperature drops and the gauge indicator moves to the LIQUID position and indicates a full converter. 8-3 1. STORAGE TANK PRESSURE GAUGE (P-1) 2. STORAGE TANK LIQUID LEVEL GAUGE (LG-1) 3. CONVERTER VENT LINE SHUTOFF V ALVE (GV-4) 4. TRANSFER TANK VENT LINE SHUTOFF V ALVE (GV-3) 5. TRANSFER TANK FILL LINE SHUTOFF V ALVE (LV-2) 6. TRANSFER TANK PRESSURE BUILDUP V ALVE (GV-5) 7. TRANSFER TANK LIQUID LEVEL GAUGE (LG-2) 8. TRANSFER TANK PRESSURE GAUGE (P-2) 9. CONVERTER FULL INDICATOR GAUGE (F1) 10. FILL-DRAIN LINE SHUTOFF V ALVE (LV-1) 11. STORAGE TANK VENT LINE SHUTOFF V ALVE (GV-6) 12. FILLER V ALVE (C-2) 13. CONVERTER VENT LINE CONNECTION (C-3) 14. FILL-DRAIN LINE COUPLING (C-1) Figure 8-2.—Liquid oxygen servicing trailer controls and indicators.

CAUTION The fill-drain line shutoff valve is not used to control flow. Restricting transfer flow may create a dangerous back-pressure on the supply line used for filling. Control of transfer flow should be maintained with the service valve of the central supply tank. FILL-DRAIN LINE SHUTOFF V ALVE.—(Fig. 8-2, item 10). The fill valve is used during the storage tank filling operation to permit the flow of oxygen from a central supply tank. The shutoff valve is opened completely during the filling function and then closed after the transfer has been completed. STORAGE TANK VENT LINE SHUTOFF VA LV E.—(Fig. 8-2, item 11). The vent valve is used to control the release of gaseous vapors from the storage tank to the vent-piping manifold. The valve is open during filling to vent all pressure from the storage tank. During normal idle storage, the valve is left in the open position to vent all vapors generated by normal liquid oxygen boil-off. When the cart is not in use, the valve is left closed to prevent oxygen contact with flammable liquids or vapors. 8-4 1. FILL-DRAIN LINE COUPLING (C-1) 2. FILL-DRAIN LINE FILTER (LF-1) 3. FILL-DRAIN LINE SHUTOFF V ALVE (LV-1) 4. FILL-DRAIN LINE RELIEF V ALVE (RV-3) 5. STORAGE TANK VENT LINE SHUTOFF V ALVE (GV-6) 6. STORAGE TANK LIQUID LEVEL GAUGE (LG-1) 7. STORAGE TANK PRESSURE GAUGE (P-1) 8. STORAGE TANK INNER SHELL RELIEF V ALVE (RV-1) 9. STORAGE TANK INNER SHELL RUPTURE DISC (SD-1) 10. TRANSFER TANK FILL LINE SHUTOFF V ALVE (LV-2) 11. TRANSFER TANK VENT LINE SHUTOFF V ALVE (GV-3) 12. TRANSFER TANK PRESSURE GAUGE (P-2) 13. TRANSFER TANK LIQUID LEVEL GAUGE (LG-2) 14. TRANSFER TANK INNER SHELL RELIEF V ALVE (RV-2) 15. TRANSFER TANK INNER SHELL RUPTURE DISC (SD-3) 16. CONVERTER VENT LINE CONNECTOR (C-3) 17. FILLER V ALVE (C-2) 18. CONVERTER VENT LINE CHECK V ALVE (CV-1) 19. CONVERTER FULL INDICATOR GAUGE (F1) 20. CONVERTER VENT LINE SHUTOFF V ALVE (GV-4) 21. TRANSFER TANK PRESSURE BUILDUP V ALVE (GV-5) 22. OUTER SHELL RELIEF DEVICE (SD-2) 23. CONVERTER V APOR RETURN CHECK V ALVE (CODE C AND D) Figure 8-3.—TMU-70/M liquid oxygen servicing trailer schematic diagram.

Operation The following procedures describe LOX flow in connection with filling the TMU-70/M storage tank and the servicing of an aircraft converter, using the trailer. The flow description is keyed to figure 8-3. Figure 8-4 shows the operating instructions from the plate attached to the trailer. When the servicing trailer is received from the factory or from an overhaul activity, it is normally ready to be filled with LOX and pressurized for immediate use. The annular space is evacuated to the point 8-5 Figure 8-4.—Operating instructions for TMU-70/M.

desirable for a warm and empty tank. Prior to filling or pressurizing the tank, perform the inspection proce- dures indicated in table 8-1. FILLING.—Normally the servicing trailer is filled from central supply tanks. These tanks have transfer hoses terminating in couplings that match the fill-drain line coupling on the trailer. Operation of the supply tank should be in accordance with the procedures in its operation manual. Filling consists of the following procedures. Ensure that all required safety equipment is in use and all safety precautions have been taken. Place the trailer on a level surface or ensure that the tank has a level position. Close all control valves on the storage tank. Pressurize the LOX supply tank to the required pressure for transfer to the TMU-70/M. Remove the dust cover from the supply tank transfer line and purge hose. After purging, connect the fill-drain line coupling (1) (fig. 8-3) to the transfer hose. Open the TMU-70/M’s storage tank vent line shutoff valve (5) and fill drain line shutoff valve (3). 8-6 ITEM INSPECTION FREQUENCY Exterior Inspect for obvious physical damage, missing parts, illegible decals or plates, and missing or insecure attaching parts. Daily while in use Piping and valves Inspect for dents, nicks, or scratches; security of brazed or threaded connections; ease of valve movement, and adequate seating and security of packings. Daily while in use Gauges Inspect for cracked dial face and security of installation. Daily while in use Cabinet Inspect for smooth hinge and guide operation and correct functioning of latches and legibility of decals and plates. Daily while in use Tires Inspect for correct inflation, tread wear, sidewall cracks or abrasions, and proper positioning of valve stems. Daily while in use Wheel assemblies Inspect for warps or dents in rims and freedom of rotation. Daily while in use Retractable caster Inspect for proper operation and undue wear or damage. Daily while in use Controls Inspect for loose, missing, or cracked handles; obvious physical damage. Daily while in use Brake and cross shaft assemblies Inspect for physical damage, missing parts, and ease of operation. Daily while in use Converter fill and vent line hoses Inspect for frayed wire in braid and worn or damaged fill and vent couplings. Daily while in use Exterior cleanliness Inspect visually for such contaminants as oil, grease, metal chips or scale. Weekly Operation Perform operational checkout Monthly or on receipt of new or repaired equipment Table 8-1.—Periodic Inspection

CAUTION Pressure should not be allowed to rise above 55 pounds per square inch (psi) in the storage tank. Monitor the storage tank pressure gauge (7) closely during cooldown. Open the service valve on the supply tank slowly, and allow only a partial flow of LOX through the transfer hose and into the trailer. Considerable vaporization will take place until the transfer hose, fill-drain line, and storage tank on the trailer have cooled down. When these have sufficiently cooled and are able to handle a full flow of LOX, open the service valve on the supply tank completely. During filling, LOX flow is through the fill-drain line filter (2) and shutoff valves (3) to the storage tank. The relief valve (4) is provided to prevent excessive pressure if the fill-drain line shutoff valve and the service valve on the supply tank are closed with cold gas or liquid trapped within the supply line. The relief valve (4) is connected to the vent line for safe discharge overboard. The vent line shutoff valve (5) is opened during filling and normal storage where safe overboard discharge is provided. Storage tank conditions are monitored and indicated by the liquid level gauge (6) and pressure gauge (7). The inner shell relief valve (8) and rupture disc (9) are provided in case of excessive pressure in the storage tank. Monitor the storage tank liquid level gauge (6) during filling. When it indicates 50 gallons or LOX starts to flow out the vent manifold, close the servicing valve on the supply tank. Close the fill-drain line shutoff valve (3) to relieve internal pressure. CAUTION Use extreme caution when disconnecting the transfer hose. Even though the hose has been drained and the pressure relieved, some LOX will still remain. Do not direct the hose toward personnel or other equipment. Disconnect the supply tank transfer hose, immediately drain the LOX that remains, and replace the coupling cap loosely. Tighten the cap after ensuring that all LOX has vaporized and bled off. Close all control valves on the service trailer except the storage tank vent valve (5). NOTE: Observe the time required to fill the TMU-70/M. Filling will vary with each supply tank and supply system. Under normal conditions and 30 psi transfer pressure, the storage tank should fill within a period of 5 to 10 minutes. Deviation from the average filling time should be cause for investigation. TRANSFER.—The transfer of LOX from the storage tank of the trailer to an aircraft converter can be done in the following manner. Ensure that all safety equipment is in use. Close all control valves (3, 5, 10, 11, 20, and 21, as show in figure 8-3). Observe storage tank liquid level gauge (6) and pressure gauge (7) to ensure sufficient LOX supply and safe operating pressure. Open the transfer tank fill valve (10) and vent valve (11) to allow the transfer tank to fill. When the transfer tank is full, as indicated by the liquid level gauge (13), close the shutoff valves (10) and (11). Connect the converter vent line connector (16) to the converter vent fitting. Connect the air force (AF) filler valve (17) to the converter fill fitting, using a two-step procedure. First, position the valve against the purge fitting and turn the housing clockwise, locking the valve in place. Second, push the knurled knob forward and rotate clockwise, locking the valve in the open position. Open the transfer tank pressure buildup valve (21) momentarily and observe the tank pressure gauge (12). When pressure rises to approximately 90 psig, close valve (21). If necessary, maintain desired pressure by regulating pressure buildup valve (21) during converter servicing. Open the converter vent line shutoff valve (20) and observe the converter full indicator gauge (19). The gauge will indicate GAS as the converter is filling, and when full, it will indicate LIQUID. As soon as it indicates LIQUID, disconnect the AF filler valve (17), close the transfer tank pressure valve (21), close the converter vent valve (20), and then disconnect the converter vent line connector (16). If no other converters are to be serviced, empty the transfer tank, open the fill line shutoff valve (10), and then the pressure buildup valve (21), if necessary, and observe the liquid level gauge (13). When the transfer tank is empty, close the pressure buildup valve (21) and then the fill line shutoff valve (10). Close all valves except the storage tank vent valve (5). The flow of LOX from the storage tank to the aircraft converter is done as follows and can be traced using figure 8-3. The flow of LOX from the storage 8-7

tank to the transfer tank is by gravity. It first passes through the transfer fill line shutoff valve (10) to the transfer tank. During this process, the gaseous oxygen produced by cooldown of the tank is vented back to the storage tank through the vent line shutoff valve (11). Conditions of the transfer tank are monitored and indicated by pressure gauge (12) and liquid level gauge (13). When the transfer tank is filled to the desired level, as indicated by the liquid level gauge, valves (10) and (11) are closed. The converter lines are connected to the vent line connector (16) and filler valve (17). The filler valve is opened to allow the pressure in the converter and transfer tank to equalize. The transfer tank PBU coil is used to increase the pressure in the transfer tank to approximately 90 psig. This pressure is regulated by the pressure buildup valve (21) as required to maintain as high a pressure as possible during the servicing operation. W ARNING The rate of pressure buildup depends on the liquid level in the transfer tank. In a full tank, the pressure will build extremely fast because of the small amount of vapor space to be filled. Use extreme caution in building the pressure, and never allow the pressure to exceed 90 psig. Open transfer tank vent valve (11) to relieve the excessive pressure into the storage tank. This will avoid the opening of the relief valve (14) and the resultant undesirable discharge of gaseous oxygen from the vent line. LOX is now able to flow from the transfer tank into the converter. When the converter full indicator gauge (19) indicates full, the overflow is returned to the storage tank by passing through the converter vent line shutoff valve (20). The filler valve (17) is then removed, the transfer tank pressure buildup valve (21) is closed, vent valve (20) is closed, and then vent line connector (16) is disconnected. The preceding process is repeated either until the storage tank is empty or the maximum operating pressure, as indicated on the storage tank pressure gauge (7), has been replaced. Maintenance Information and instructions for maintenance of the TMU-70/M storage tank are found in NA V AIR 19-25D-26. The maintenance section is organized to provide information and instructions for the three levels of maintenance responsibility: organizational, intermediate, and depot. The capability of the using or supporting activity will be the limiting factor as to the level of maintenance that can be performed on the equipment. If maintenance of the equipment is beyond the assigned maintenance responsibility of the using or supporting activity, the next higher level will perform the maintenance. AMEs are only responsible for the organizational maintenance of LOX trailers, which includes those functions normally performed in support of daily operations. Normal operational maintenance func- tions include inspection and preventive maintenance. Table 8-1 will assist you in understanding these functions. System Servicing Aircraft systems and LOX converters should be serviced in accordance with the appropriate mainte- nance instructions manual (MIM). Only LOX conforming to MIL-0-27210, type II, may be used in aircraft LOX systems. The firefighting agents below are prohibited from use in conjunction with LOX-enriched fires. • Soda-acid extinguishers • Mechanical (liquid) foam • Methyl bromide • Carbon tetrachloride Q8-1. Open flames, smoking, or sparks should be kept what minimum distance away from a LOX handling area? Q8-2. True or False. Oxygen will burn when ignited. Q8-3. Identify the three major components of the TMU-70/M. Q8-4. Explain the primary function of the transfer tank. Q8-5. What is the function of the transfer tank pres- sure buildup valve? Q8-6. Using the fill-drain shutoff valve to control LOX flow may cause what type of hazard? Q8-7. Exterior cleanliness of the TMU-70/M LOX cart should be performed at what interval? 8-8

Q8-8. Information and instructions for maintenance of the TMU-70/M are found in what publica- tion? Q8-9. What type of LOX must be used to service aircraft LOX systems? CONTAMINATION CONTROL LEARNING OBJECTIVE : Describe con- tamination control procedures for oxygen equipment to include detection, purging, and purging equipment. The importance of using uncontaminated LOX in aircraft systems cannot be overstressed. Because of this, the Navy has established the Aviators Breathing Oxygen (ABO) Surveillance Program Laboratory and Field Guide (A6-332SAO-GYD-000). For additional information on contamination control, oxygen sam- pling, and oxygen system purging, refer to that manual. LOX produced by generating plants contains contaminants, which are not completely removed by the generating process. Atmospheric air, from which LOX is generated, is the primary source of contamination. Additional sources of contamination are the compressors and other equipment of the generating plants. Airborne contaminants and those added by the generating plants are partially removed by a system of filters, absorbers, driers, and heat exchangers before the air is finally liquefied. When the LOX separates from the liquefied air it carries with it those contaminants that are not completely removed. The variety and concentration of contaminants that separate with the LOX depend on how effective their removal has been during the generating process. Generating plants are designed to remove contamina- tion to the lowest limits possible, both for safety of operation and for quality of product. The contamination limits of LOX produced by any generating plant for the Navy and Marine Corps as breathing oxygen are specified as procurement limits. Procurement limits and the ultimate use limits of contamination are based on the types and significance of contaminants, and the sources of increasing contamination in liquid oxygen during storage, handling, and transfer. DETECTION LOX contamination is detected by means of an odor test, sampling, and analysis. Only the odor test will be discussed in this chapter because all other tests and analysis must be performed in a laboratory. An odor test will be performed on LOX trailers after the first filling of the day, or each 6 days when the trailer is not in service. Aircraft LOX systems require an odor test to be performed as soon as possible after an aircraft accident/incident or a report of in-flight odors by pilots or aircrew. The sample taken after an accident/incident must be sent to a test site for analysis with details of the incident, including history of the supply source of the LOX. Odor Test The odor test is performed by pouring a 200-milliliter (6.8 oz) sample into a clean 400-milliliter (13.8 oz) beaker or similar container after covering the bottom of the beaker with clean, dry filter paper or other absorbent paper. A watch glass cover or some other means of partially covering the top of the beaker will be provided as the 200 milliliters evaporates to dryness. This will prevent atmospheric elements from being absorbed by the exposed liquid. The liquid is permitted to evaporate to dryness and warm up to approximately room temperature in an area free from air currents or extraneous odors. When the liquid has completely evaporated, the watch glass is removed and the beaker contents smelled at frequent intervals until the accumulated frost on the outside of the beaker has completely melted. Odors will be most prevalent when the beaker has warmed to nearly room temperature. If odors are present, the LOX container or system will be purged in accordance with existing directives. Sampling Sampling and analysis of LOX is required any time contamination is suspected. Contamination of oxygen used in aircraft can cause many problems, from fire hazards to death of the crewmember using the oxygen system. The most dangerous contaminate is hydrocarbons. The presence of hydrocarbons in LOX constitutes a potential fire and explosive hazard as well as causing psychological and physiological dangers to aircrews. Psychologically, the effects may be uneasiness, apprehension, or possible panic resulting from detection of odors. Physiologically, the effects may be nausea, illness, intoxication, or possibly asphyxia. Acetylene is the most hazardous hydrocarbon contaminate because it is highly insoluble in LOX, changing into a solid at extremely low concentrations. Once in its solid form, it can readily be set off into ignition, and since it is chemically unstable, it can decompose under certain conditions and become its own source of ignition. The presence of acetylene in 8-9

LOX has caused several major LOX generating plant explosions. Inert solids are small contaminants that do not react with oxygen to create a fire or explosion, such as rust, dust, and fibers. They may cause mechanical malfunctions or failures by plugging filters, lines, or valves. Other contaminants commonly found in oxygen are water vapor, carbon dioxide, nitrous oxide, and halogenated compounds (Freons). PURGING Purging and other maintenance of LOX trailers is performed by the Aviation Support Equipment Technician (AS) rating. Purging is the cleansing of impurities from oxygen systems and containers. There are two ways to purge oxygen containers: LOX wash and gas purging. The LOX wash method is used on large containers, such as storage tanks and LOX trailers, to lower the contamination to acceptable levels by replacing the contaminated LOX with LOX known to be un- contaminated. Gas purging is used on aircraft LOX converters if the system pressure is allowed to deplete or if odor is detected. Gas purging of aircraft LOX systems must be done if any maintenance is performed on the system that opens it to the atmosphere. Q8-10. What manual should you refer to for information on contamination control for oxygen? Q8-11. What is the primary source of contamination for LOX? Q8-12. State the three ways LOX contamination is detected. Q8-13. An odor test will be performed on a LOX cart if it has not been in service for what amount of time? Q8-14. When is LOX sampling performed? Q8-15. Of all the hydrocarbons associated with LOX, why is acetylene the most dangerous? Q8-16. List four contaminants commonly found in oxygen. Q8-17. What rate is responsible for purging of LOX trailers? GASEOUS OXYGEN SERVICING TRAILERS LEARNING OBJECTIVE: Identify compo- nents and operating procedures for gaseous oxygen servicing trailers. There are several different models of gaseous oxygen servicing trailers currently in use by naval activities. This section will discuss the type No-2 and the A/U26U-1A oxygen servicing unit. TYPE NO-2 GASEOUS OXYGEN SERVICING TRAILER The type No-2 servicing trailer is shown in figure 8-5. Equipment provided on the trailer includes six manifold control valves with pressure gauges, an upper and lower manifold, two pressure regulators, a recharge valve, four shutoff valves, a drier assembly, six cylinders and connecting flexible hoses, and a servicing hose fitted with a line servicing valve fitted with a high-pressure charging adapter. The function of each of these components is described in the following text. Components Complete familiarity with the following trailer components is a basic prerequisite for safe operation. MANIFOLD CONTROL V ALVES .—The six manifold control valves serve to shut off the flow of oxygen from the cylinders to the system being charged. These valves are lever-type valves. The manifold control valves should not be used as a shutoff for long-time storage. Always use the hand-wheel type valves located on the cylinders. UPPER MANIFOLD .—The upper manifold provides connections/mounting for the six manifold control valves with pressure gauges (each connected to a supply cylinder), a recharge valve, and two upper/inlet shutoff valves that connect to the inlet side of the regulators. PRESSURE REGULATORS .—The pressure regulator controls the charging pressure when the trailer is being used to service aircraft oxygen systems. Only one pressure regulator is used during operation. The spare is provided to ensure uninterrupted operation should one fail. RECHARGE V ALVE.—The recharge valve is provided as a means of recharging the trailer cylinders directly through the upper manifold without the 8-10

necessity of removing the cylinders. When not in use, the valve adapter should be fitted with a dust cap. SHUTOFF V ALVES.—There are four shutoff valves, one on the inlet side of each pressure regulator and one on the outlet side of each regulator. These shutoff valves control the flow of oxygen from the upper manifold to the lower manifold, via the regulator. When the shutoff valves on the inlet and outlet sides of the regulator are open, the pressure regulator is ready for use. By turning the regulator control handle clockwise, the pressure (as read on the gauge attached to the regulator) will increase. Turning the control handle counterclockwise decreases pressure. LOWER MANIFOLD .—The lower manifold provides connections/mountings for the two lower/outlet shutoff valves from the outlet side of the regulators, a delivery pressure gauge, and a flexible hose that connects the lower manifold to the drier assembly. DRIER ASSEMBLY.—The drier assembly is a reservoir containing a chemical drying agent through which oxygen must pass before going through the servicing hose. This chemical drier is provided to remove any moisture in the oxygen supply. The oxygen flows into the bottom of the drier, passes up through the drying agent, and out through the servicing hose. SERVICING HOSE AND LINE V ALVE.—The servicing hose is a high-pressure, non-linking, metallic flexible hose. The line-servicing valve is attached to the servicing hose and is used to control the flow of oxygen to the system being charged. 8-11 Figure 8-5.—Type No-2 gaseous oxygen servicing trailer.

Operation The six supply cylinders are connected by means of flexible hoses to their respective control valves (fig. 8-6). The six control valves are attached to the upper manifolds. A pressure gauge is screwed into each control valve at a point below the seat. This allows each cylinder pressure to be easily read. The oxygen flows from the upper manifold through either of two pressure regulators via two shutoff valves. The oxygen is collected in the lower manifold where a gauge registers the pressure of the delivery side of the system. The lower manifold is connected by flexible hose to a drier that filters and dries the oxygen. The servicing hose connects directly to the drier and has a line-servicing valve on the terminal end. The line-servicing valve is fitted with a standard oxygen cylinder connection. Loading Cylinders The servicing trailer is capable of having its cylinders recharged without removal. However, many operating activities replace the empty cylinders with full cylinders. NOTE: NEVER completely expend the supply of oxygen from a cylinder. Always leave a residual pressure in excess of 50 psi. REMOV AL OF EMPTY CYLINDERS.—When the trailer has been in use and cylinder pressure is low, the cylinders are removed as described below. 1. Close all lever valves on the manifold prior to removing any cylinders. 2. Close the cylinder shutoff valves. 3. Disconnect the flexible hose that connects the cylinder to the manifold. 4. Loosen the clamping arrangement that holds the cylinders to the trailer. 5. Install the cylinder safety caps. 6. Remove the empty cylinders. CAUTION Do not attempt to remove empty cylinders while charging. 8-12 Figure 8-6.—Type No-2 gaseous oxygen servicing trailer (schematic).

INSTALLATION OF FULL CYLINDERS .— The trailer should be loaded with cylinders while fastened to a towing vehicle. If a towing vehicle is not available, the rear stand should be let down and hand brakes applied so the weight of the cylinders will not cause the trailer to tilt backwards. The retractable swivel wheel should be down if the trailer is not hooked to a towing vehicle. (When the trailer is hooked to the towing vehicle, the swivel wheel should be retracted). Cylinders should be loaded from the rear and should be handled with safety caps in place. Standing cylinders should be brought to within 4 feet of the rear end of the trailer. If the cylinders are lying down, the safety cap end of the cylinder should be just below the rear of the trailer. The safety cap end of the cylinder should be lifted or lowered and placed in the appropriate channel. The bottom of the cylinder should be raised and the cylinder worked into place. Ensure that the cylinder is in its forward-most position and firmly seated against the forward cylinder stop. Remove the cylinder safety cap. Position the cylinder so that the cylinder valve outlet may easily be connected to the flexible hose without causing undue strain on the hose. Prior to connecting the hose to the cylinder, open the cylinder valve slightly to blow any foreign matter from the outlet valve, then close the valve. Connect the flexible hose nut to the power cylinder valve. As soon as the cylinders are in place and the hoses connected, the clamping arrangements should be tightened. The bottom four cylinders are clamped in pairs by a wheel while the top two cylinders are each held in place by a single strap. After tightening the coupling nuts on the hoses, the hoses should be free of twisting strain. Gripping the hose with one hand and twisting slightly in a clockwise direction while tightening the coupling nut can prevent twisting. After replacing the empty cylinders, the cylinder valves on the full cylinders should not be opened until the trailer is positioned for servicing an aircraft. CAUTION To eliminate the danger of an explosion, do not interchange parts between oxygen servicing equip- ment and air/nitrogen equipment. REPLACEMENT OF DRYING AGENT.—The chemical drier should be inspected after every 12 cylinders are used, and the chemical agent should be replaced at the first sign of change in the indicator. The blue-colored indicating agent is applied on top of the white drying agent. When moisture is present, the indicating agent will change color from blue to pink. The indicating agent can be easily inspected by removing the servicing hose and unscrewing the top cap of the drier container. CAUTION Relieve all pressure prior to inspection or re- placement of the chemical agent. The drying agent is removed by removing the hose connecting the lower cap and the lower manifold and unscrewing the drier lower cap. All traces of the contaminated agent should be removed and the lower cap replaced, and the lower manifold connected. The drying agent should be quickly placed in the drier so that it does not pick up moisture from the air. Care should be given to the replacement of the indicating agent. The top cap should be screwed in place immediately after observing the condition of the indicator so that moisture or humid air does not cause the indicator to change color. The caps on the drier should be screwed down until they hit bottom. The caps should be removed and replaced by hand only. It is not necessary to tighten the caps extremely tight; the caps are sealed with O-ring packings. If leakage occurs, the O-rings should be replaced. NOTE : All maintenance on the oxygen-servicing trailer should be performed in accordance with the instructions contained in the applicable operation and service instruc- tions manual or set of maintenance require- ment cards. OXYGEN SERVICING UNIT A/U26U-1A The oxygen servicing unit A/U26U-1A is a configuration of four major components consisting of a trailer assembly, gas storage system, gas servicing 8-13

system, and interface/servicing equipment. Figures 8-7 and 8-8 illustrate the relationship of major components and location of information plates and reflective tape. Components Components include a trailer assembly, gas storage system, gas servicing system, and interface/servicing equipment. TRAILER ASSEMBLY.—The trailer assembly is designed to support and transport the gas storage system, gaseous oxygen/nitrogen modules, and interface/servicing equipment including the grounding reel cable assembly. The trailer contains three wheels and a tow bar. The tow bar is used to attach the trailer to a towing vehicle. A rotatable, retractable swivel caster wheel supports the tow bar when the trailer is uncoupled from a tow vehicle. The wheel release handle holds the swivel caster wheel in the up position when the trailer is being towed. When uncoupled, the caster wheel is locked in the down position with the wheel release handle. The trailer is equipped with a mechanical parking brake operated by a hand brake lever. GAS STORAGE SYSTEM .—The gas storage system is used to store oxygen and nitrogen. It consists of one cylinder of oxygen and two cylinders of gaseous nitrogen (oil free). The storage system is designed to operate at 225-3850 psig for nitrogen and 200 to 2640 psig for oxygen. Nitrogen is used to drive an oxygen boost pump when compressed air is not available. 8-14 Figure 8-7.—Oxygen servicing unit A/U26U-1A.

GAS SERVICING SYSTEM .—The gas servicing system is used to supply oxygen to an aircraft oxygen storage system. The system consists of the gaseous oxygen module and nitrogen module. CAUTION Compressed air used to drive the oxygen gas boost pump must be clean and moisture free. 8-15 1. TRAILER ASSEMBLY 2. NITROGEN MODULE 3. OXYGEN MODULE 4. OXYGEN STORAGE CYLINDER 5. NITROGEN STORAGE CYLINDER 6. SERVICING/INTERFACE EQUIPMENT STORAGE 7. PARKING BRAKE HANDLE 8. PUSH BAR 9. NOSE WHEEL RELEASE HANDLE 10. SAFETY CHAIN AND HOOK 11. RETRO-REFLECTIVE TAPE 12. LIFTING INSTRUCTION PLATE 13. TRANSPORTATION DATA PLATE 14. IDENTIFICATION PLATE 15. GROUNDING REEL CABLE ASSEMBLY Figure 8-8.—Oxygen servicing unit A/U26U-1A.

Gaseous Oxygen Module.—The gaseous oxygen module (fig. 8-9) transfers oxygen from the gas storage system by equalizing pressure or by boosting with a pump driven by compressed air or gaseous nitrogen. The two oxygen delivery pressures provided are for high pressure (HP) and low pressure (LP) aircraft oxygen serving. During aircraft oxygen servicing, the oxygen module is grounded to the nitrogen module and trailer grounding reel. Gaseous oxygen (aviator’s breathing) used with this unit shall conform to the current military specification MIL-0-27210, type I (gaseous, 99.5 percent pure). W ARNING Do not interchange parts between nitrogen module and oxygen module. 8-16 Figure 8-9.—Gaseous oxygen module.

Gaseous Nitrogen Module .—The gaseous nitrogen module (fig. 8-10) supplies unregulated compressed air (90 to 150 psig) or regulated gaseous nitrogen (120 to 130 psig) to the oxygen module for oxygen boost pump drive. Compressed air is the primary drive source for the boost pump. Gaseous nitrogen will only be used as a drive source for boost pump when compressed air is not available. Gaseous nitrogen used for recharging this unit shall conform to federal specification BB-N-411, type 1 (gaseous), Class 1 (oil free), Grade B (99.5 percent pure, low moisture content). 8-17 Figure 8-10.—Gaseous nitrogen module.

INTERFACE/SERVICING EQUIPMENT .— The interface/servicing equipment (fig. 8-11) consists of those parts required to connect the oxygen-servicing unit to the aircraft oxygen storage system and includes the grounding cable reel assembly. The servicing equipment provides an HP and LP oxygen supply connection for aircraft oxygen storage cylinders and emergency bailout systems. The interface equipment consists of connecting hoses between oxygen/nitrogen modules, which convey air or nitrogen to drive the oxygen boost pump. 8-18 32. OXYGEN SERVICE HOSE PN 1828AS137-1 33. OXYGEN SERVICE V ALVE PN 1828AS179-1 34. SERVICE ADAPTER CONNECTION PN MS33656E4 35. HP SERVICE ADAPTER PN 1828AS138-1 36. LP SERVICE ADAPTER PN 1828AS139-1 37. LP ADAPTER BURST DISC PN 1828AS177-1 38. HP ADAPTER BURST DISC PN 1828AS178-1 40. BOOST PUMP DRIVE HOSE PN 1828AS143-1 41. OXYGEN BENCH SUPPLY HOSE (SHIP/SHOP PN 1828AS140-1 42. GROUNDING CABLE REEL ASSEMBLY PN ML-2930-34 (61349) 43. HP SERVICE ADAPTER (AIRCRAFT) PN 1426AS136-1 Figure 8-11.—Oxygen/nitrogen interface/servicing equipment.

Operation The operational functions of the oxygen-servicing unit are HP and LP aircraft oxygen servicing, HP and LP oxygen shop servicing, and gaseous nitrogen recharging. Aircraft servicing shall be performed in ambient temperatures of –30°F to 125°F in various environmental conditions. Figure 8-12 illustrates the 8-19 1. NITROGEN STORAGE CYLINDERS 2. OXYGEN STORAGE CYLINDER 3. NITROGEN CYLINDER V ALVES 4. OXYGEN CYLINDER V ALVE 5. NITROGEN SUPPLY PRESSURE GAUGE (0-5000 PSIG) 6. HP MANIFOLD 7. OXYGEN SUPPLY PRESSURE GAUGE (0-3000 PSIG) 8. NITROGEN SUPPLY V ALVE 9. PRE-SET REGULATOR 10. SHIP AIR CONNECTION 11. N 2 RECHARGE CONNECTION 12. RECHARGE CHECK V ALVE 13. FILTER 14. BOOST PUMP DRIVE PRESSURE GAUGE (0-200 PSIG) 15. BOOST PUMP DRIVE VENT 16. LP BURST DISC (180 PSIG) 17. BOOST PUMP DRIVE V ALVE 18. LP MANIFOLD 19. SELECTOR V ALVE 20. BOOST PUMP 21. EXHAUST 22. NO PILOT V ALVE 23. NC PILOT V ALVE 24. RELIEF V ALVE (2900 PSIG) 25. PURIFIER 26. FILTER 27. OXYGEN VENT V ALVE 28. REGULATOR INLET PRESSURE GAUGE (0-3000 PSIG) 29. OXYGEN REGULATOR 30. REGULATOR OUTLET PRESSURE GAUGE (0-3000 PSIG) 31. OXYGEN SERVICE CONNECTION 32. SERVICE HOSE 33. SERVICE V ALVE 34. SERVICE ADAPTER CONNECTION 35. HP SERVICE ADAPTER 36. LP SERVICE ADAPTER 37. LP ADAPTER BURST DISC (600 PSIG) 38. HP ADAPTER BURST DISC (2590 PSIG) 39. PRE SET REGULATOR FILTER 40. HP SERVICE ADAPTER (AIRCRAFT) Figure 8-12.—Air/nitrogen boost pump drive and oxygen servicing flow schematic.

component locations and the oxygen flow; table 8-2 describes the functions of the servicing controls and indicators as shown in figure 8-12. HP AND LP AIRCRAFT SERVICING .—The HP and LP aircraft oxygen servicing operational function involves the mobile servicing of aircraft 8-20 ITEM NAME FUNCTION 3 Hand valves on nitrogen gas storage cylinders Isolates the nitrogen storage cylinders. 4 Hand valve on oxygen gas storage cylinder Isolates the oxygen gas storage cylinder. 5 Nitrogen supply pressure gauge on nitrogen module Displays nitrogen cylinder gas pressure. 7 Oxygen supply pressure gauge on oxygen module Displays oxygen cylinder gas pressure. 8 Nitrogen supply valve on nitrogen module Prevents nitrogen flowing to a pre-set pressure regulator when recharging the nitrogen gas storage cylinder. 14 Boost pump drive pressure gauge on nitrogen module Displays nitrogen gas or air pressure being delivered to the boost pump. 15 Boost pump drive valve on nitrogen module Vents the boost pump drive gas pressure and nitrogen module gas line pressure for parts disconnecting. 16 LP burst disc Prevents the boost pump drive air pressure from exceeding 180 psig. 17 Boost pump drive valve on nitrogen module Provides positive control of air or nitrogen gas to the boost pump. 19 Selector valve on oxygen module Provides control of oxygen delivered to the boost pump or bypasses oxygen around the boost pump. Also, provides system off control. 24 Relief valve in oxygen module Relieves excess pressure if boost pump outlet pressure exceeds 2900 psig. 27 Oxygen vent valve on oxygen module Vents oxygen gas upstream of regulator. 28 Regulator inlet pressure gauge on oxygen module Displays inlet gas pressure to the oxygen regulator. 29 Oxygen regulator in oxy- gen module Regulates oxygen delivery pressure to the aircraft oxygen gas storage system. 30 Regulator outlet pressure gauge on oxygen module Displays outlet gas pressure of oxygen regulator. 33 Service valve on service equipment Positive control for ON-OFF delivery to aircraft storage system. Vents upstream pressures for parts disconnect. 37 Low pressure service adapter burst disc Prevents low pressure aircraft oxygen gas storage system from exceeding 600 psig. 38 High pressure service adapter burst disc Prevents high pressure aircraft oxygen gas storage system from exceeding 2400 psig. Table 8-2.—Servicing Controls and Indicators

oxygen storage systems to a HP of 1800 psig and LP of 500 psig. NITROGEN RECHARGING .—This opera- tional function involves charging two gaseous nitrogen cylinders. The nitrogen cylinders have a pressure range of 225 to 3850 psig. When recharging the cylinders, the nominal pressure is 3500 psig to a maximum of 3850 psig. Q8-18. The type No-2 gaseous oxygen-servicing trailer has how many manifold control valves? Q8-19. What component on the type No-2 cart controls the charging pressure when the trailer is servicing aircraft oxygen systems? Q8-20. An oxygen cylinder should never be completely drained. How much residual pressure should be kept in the cylinder? Q8-21. True or False. Parts for a No-2 cart can be interchanged with those on a nitrogen cart. Q8-22. The A/U26U-1A gaseous nitrogen module supplies what amount of regulated gaseous nitrogen to the oxygen module? Q8-23. Gaseous nitrogen on the A/U26U-1A shall conform to what federal specification? Q8-24. When using the A/U26U-1A, what is the maximum allowable ambient temperature when servicing aircraft? 8-21

CHAPTER 8 ANSWERS TO REVIEW QUESTIONS A8-1. Fifty feet A8-2. False A8-3. A 50-gallon Dewar storage tank, 15-liter Dewar transfer tank, and a low loss, closed loop system of transfer lines A8-4. Holds small volumes of LOX and uses cold gas pressure from the pressure buildup unit to transfer LOX to the aircraft converter A8-5. Controls the gravity flow of liquid oxygen from the storage tank to the transfer tank A8-6. Dangerous back-pressure A8-7. Weekly A8-8. NAVAIR 19-25D-26 A8-9. Only LOX conforming to MIL-0-27210, type II A8-10. Aviators Breathing Oxygen (ABO) Surveillance Program Laboratory and Field Guide (A6-332SAO-GYD-000) A8-11. Atmospheric air A8-12. Odor test, sampling, and analysis A8-13. Six days A8-14. Whenever contamination is suspected A8-15. It is highly insoluble in LOX, and changing into a solid form, it can be readily set off into ignition. Since it is chemically unstable, it can decompose under certain conditions and become its own source of ignition. A8-16. Water vapor, carbon dioxide, nitrous oxide, and halogenated compounds (Freons) A8-17. AS rate A8-18. Six A8-19. Pressure regulators A8-20. 50 psi A8-21. False A8-22. 120 to 130 psig A8-23. Federal Specification BB-N-411, Type 1 (gaseous), Class 1 (oil free), Grade B (99.5 percent pure, low moisture content) A8-24. 125°F 8-22

APPENDIX I GLOSSARY ABO—Aviators breathing oxygen. ACS—Air-conditioning system. ADC—Air data computer. AIMD—Aircraft intermediate maintenance department. ALLOY—A metal that is a mixture of two or more metals. AMBIENT—Surround; adjacent to; next to. For example, ambient conditions of the immediate area such as ambient temperature, ambient humidity, ambient pressure, etc. AMP—Auxiliary power unit. ANOXIA—A complete lack of oxygen in the blood stream. APU—Auxiliary power unit. AUR—All up round. BIT—Built-in test. BLEED AIR—Hot, high-pressure air, taken from the compressor section of a jet engine. BRU—Barostatic release unit. CAD/PAD—Cartridge-activated device/propellant-actuated device. CAG—Carrier air group. CAUTION—An operating procedure, practice, etc., that if not strictly observed could result in damage to or destruction of equipment. CDI—Collateral duty inspector. CELSIUS—A temperature scale using 0 as the freezing point of water and 100 as the boiling point. The scale has 100 equal divisions between the 0 and 100 with each division designated a degree. A reading is usually written in an abbreviated form; e.g., 75°C. Formerly known as the centigrade scale, it was renamed for Andres Celsius, the Swedish astronomer who devised the scale. CF 3BR—Triflourobromomethane. CFM—Cubic feet per minute. CIWS—Close-in weapons system. CNO—Chief of Naval Operations. CO/OIC—Commanding officer/Officer-in-charge. COMNA V AIRSYSCOM—Commander Naval Air Systems Command. CONREP—Connected replenishments. CONTAMINANT—An impurity such as harmful foreign matter in a fluid. CTR—Center. DDI—Digital display indicator. ECMO—Electronic countermeasures officer. ECS—Environmental control system. EDC—Engine driven compressors. EED—Electrically activated explosive device. EI—Engineering investigation. EOD—Explosive ordnance disposal. EPA—Electronics package assembly. FCDC—Flexible confined detonating cord. FLSC—Flexible linear shaped charge. GPM—Gallons per minute. Hg—Mercury. I—Individual. IFF—Identification friend or foe. IMA—Intermediate maintenance activity. IMP—Multi-purpose initiator. INBD—Inboard. IPB—Illustrated parts breakdown. JULIAN DATE—The year and numerical day of the year identified by four numeric characters. The first character indicates the year and the remaining three characters specify the day of the year. For example, 2030 indicates the 30th day of 2002. KEAS—Knots equivalent airspeed. KIAS—Knots indicated airspeed. AI-1

KINKED—A twist or curl, as in a cable, wire, or tubing, caused by its doubling or bending upon itself. LCSU—Liquid coolant service unit. LH—Left hand. LOX—Liquid oxygen. MAINTENANCE—The function of retaining mate- rial in or restoring it to a serviceable condition. MBEU—Martin-Baker ejection unit (seat). MIM—Maintenance instruction manual. MLM—Marine location marker. MRC—Maintenance requirement card. MULTIMETER—An instrument used for measuring resistance, voltage, or amperage. NADEP—Naval aviation depot. NATOPS— Naval Air Training and Operating Procedures Standardization. NA V AIRSYSCOM—Naval Air Systems Command. NA WMU-1—Naval Airborne Weapons Maintenance Unit One. NFO—Naval flight officer. NOMENCLATURE—A system of names; systematic naming. NOTE—An operating procedure, condition, etc., which, because of its importance, is essential to highlight. NSN—National stock number. OBOGS—Onboard oxygen generating system. OJT—On-the-job training. OPNA V—Office of the Chief of Naval Operations. OUTBD—Outboard. OXIDATION—That process by which oxygen unites with some other substance, causing rust or cor- rosion. PDRM—Parachute deployment rocket motor. PPI—Program position indicator. PRESSURE—The amount of force distributed over each unit of area, expressed in pounds per square inch (psi). PSI—Pounds per square inch. PSIA—Pounds per square inch absolute. PSIG—Pounds per square inch gauge. QA—Quality assurance. QUAL/CERT PROGRAM—Qualification/certification program. RAC—Rapid action change. RFI—Ready for issue. RH—Right hand. SAFETY WIRE/LOCKWIRE— A wire set into a component to lock movable parts into a safe, secure position. SDLM—Standard depot-level maintenance. SE—Support equipment. All the equipment on the ground needed to support aircraft in a state of readiness for flight. SEA W ARS—Seawater activated release system. SENSO—Sensor operator. SERVICING—The filling of an aircraft with consum- ables such as fuel, oil, and compressed gases to predetermined levels, pressure, quantities, or weights. SMDC—Shielded mild detonating cord. SOP—Standard operating procedure. TACCO—Tactical coordinator. TENSION—A force of pressure exerting a pull or resistance. TL—Team leader. TM—Team member. TORQUE—A turning or twisting force. TOXIC—Harmful, destructive, deadly; poisonous. TYCOM—Type commander. VAC —V olts alternating current. VDC—V olts direct current. VOLATILE LIQUIDS—Liquids that are readily va- porizable at relatively low temperatures. Explosive liquids. W AM—Weapons assembly manual. W ARNING—An operating procedure, practice, etc., that if not followed correctly could result in personal injury or loss of life. XSMDC—Expanding shielded mild detonating cord. AI-2

APPENDIX II REFERENCES NOTE: Although the following references were current when this Nonresident Training Course (NRTC) was published, their continued currency cannot be assured. When consulting these references, keep in mind that they may have been revised to reflect new technology or revised methods, practices, or procedures; therefore, you need to ensure that you are studying the latest references. CHAPTER 1 Escape and Survival Systems , NA V AIR 01-85ADC-2-5, Naval Air Systems Command, Patuxent River, MD, August 2000. CHAPTER 2 Escape Systems , NA V AIR 01-F14AAD-2-2-3, Naval Air Systems Command, Patuxent River, MD, January 2000. Seat, Canopy, Survival Equipment, and Boarding Ladder , A1-F18AC-120-100, Naval Air Systems Command, Patuxent River, MD, December 1999. CHAPTER 3 Environmental Control Systems , NA V AIR 01-F14AAA-2-2-2, Naval Air Systems Command, Patuxent River, MD, March 2001. Escape and Survival Systems , NA V AIR 01-S3AAA-2-2.8, Naval Air Systems Command, Patuxent River, MD, January 1992. Escape Systems , NA V AIR 01-F14AAD-2-2-3, Naval Air Systems Command, Patuxent River, MD, January 2000. General Use Cartridges and Cartridge Actuated Devices for Aircraft and Associated Equipment, NA V AIR 11-100-1.1, Naval Air Systems Command, Patuxent River, MD, January 2002. CHAPTER 4 Explosives Handling Personnel Qualification and Certification Program , OPNAVINST8020.14,ChiefofNavalOperations,Washington,DC,October 1999. General Use Cartridges and Cartridge Actuated Devices for Aircraft and Associated Equipment, NA V AIR 11-100-1.1, Naval Air Systems Command, Patuxent River, MD, January 2002 The Naval Aviation Maintenance Program (NAMP), OPNA V 4790 series, V olume 1, Chief of Naval Operations, Washington, DC, June 2001. CHAPTER 5 Environmental Control Systems , A1-F18AC-410-100, Naval Air Systems Command, Patuxent River, MD, April 2000. AII-1

Environmental Control Systems , NA V AIR 01-S3AAA-2-2.7, Naval Air Systems Command, Patuxent River, MD, December 1998. Environmental Control Systems , NA V AIR 01-85ADC-2-6, Naval Air Systems Command, Patuxent River, MD, May 1997. Environmental Control Systems , NA V AIR 01-F14AAA-2-2-2, Naval Air Systems Command, Patuxent River, MD, March 2001. Utility Systems, NA V AIR 01-75PAA-2-2.4, Naval Air Systems Command, Patuxent River, MD, March 2001. CHAPTER 6 Environmental Control Systems , A1-F18AC-410-100, Naval Air Systems Command, Patuxent River, MD, April 2000. Environmental Control Systems , NA V AIR 01-S3AAA-2-2.7, Naval Air Systems Command, Patuxent River, MD, December 1998. Environmental Control Systems , NA V AIR 01-F14AAA-2-2-2, Naval Air Systems Command, Patuxent River, MD, March 2001. Utility Systems, NA V AIR 01-75PAA-2-2.4, Naval Air Systems Command, Patuxent River, MD, March 2001. CHAPTER 7 Aviators Breathing Oxygen (ABO) Surveillance Program and Field Guide , A6-332A0-GYD-000, Naval Air Systems Command, Patuxent River, MD, June 1997. Environmental Control Systems , NA V AIR 01-F14AAA-2-2-2, Naval Air Systems Command, Patuxent River, MD, March 2001. NA VAIROSH Requirements for the Shore Establishment , NA V AIR A1-NASOH-SAF-0001P-5100-1, Naval Air Systems Command, Patuxent River, MD, October 1998. Oxygen Equipment (Aircraft Equipment Mask and Other Systems) , NA V AIR 13-1-6.4-1, Naval Air Systems Command, Patuxent River, MD, April 2001. Oxygen Equipment (Regulators) , NA V AIR 13-1-6.4-2, Naval Air Systems Command, Patuxent River, MD, April 2001. Oxygen Equipment (Converters) , NA V AIR 13-1-6.4-4, Naval Air Systems Command, Patuxent River, MD, April 2001. Safety and Survival , NA V AIR 01-75PAA-2-2.3, Naval Air Systems Command, Patuxent River, MD, June 2000. CHAPTER 8 Gaseous Oxygen Servicing Trailer , NA V AIR 19-25D-1, Naval Air Systems Command, Patuxent River, MD, June 1998. Oxygen Servicing Unit A/U26U-1A , NA V AIR 19-25D-31, Naval Air Systems Command, Patuxent River, MD, November 1999. Servicing Trailer , Liquid Oxygen Low Loss, Closed Loop, Type TMU-70/M, NA V AIR 19-25D-26, Naval Air Systems Command, Patuxent River, MD, September 2000. AII-2

ASSIGNMENT 1 Textbook Assignment: Chapte r 1 – Martin-Baker MK-GRUEA-7 Ejection Seat and Chapte r2–N a v y Aircrew Common Ejection Seat (NACES) 1-1. The MK-GRUEA-7 seat provides crewmembers with completely automatic escape at ground level at what minimum knots? 1. 60 2. 70 3. 80 4. 90 1-2. How many Martin-Baker MK-GRUEA-7 seats are on the EA-6B? 1. One 2. Two 3. Three 4. Four 1-3. What difference, if any, do the MK-GRUEA-7 ejection seats have from each other? 1. Time delay firing mechanisms 2. Seat height 3. Seat color 4. None 1-4. What component provides an automatic backup mode of separating the parachute from the crewmember? 1. Emergency release handle 2. Guillotine breech 3. SEAW ARS 4. Time-release mechanism 1-5. What type of aircraft uses the Martin-Baker MK-GRUEA-7? 1. E-6B 2. EA-6B 3. S-3 4. F-14 1-6. Which of the following seats ejects first during ejection? 1. ECMO #1 2. ECMO #2 3. ECMO #3 4. Pilot 1-7. What color is the murphy-proof bracket for ECMO #2 seat? 1. Orange 2. Brown 3. Purple 4. White 1-8. Who is the primary person to initiate ejection? 1. ECMO #1 2. ECMO #2 3. ECMO #3 4. Pilot 1-9. With the CMD EJECT SELECT handle in the NORM position, what individual(s) is/are able to initiate ejection? 1. Pilot and ECMO #1 2. Pilot and ECMO #2 3. ECMO #1 and #2 4. ECMO #3 only 1-10. The lanyards for the ejection seat safety pins are what color? 1. Green 2. Red 3. Orange 4. Yellow 1-11. Prior to entering an aircraft cockpit that has an ejection seat, personnel should ensure which of the following guidelines is met? 1. Electrical power is applied 2. Safety pins are installed 3. Proper safety precautions are followed 4. Both 2 and 3 above 1-12. Who may work on ejection seats? 1. E5 and above 2. E5 and below 3. Any AME 4. Qualified personnel only 1

1-13. How many tubes are attached to the center body of the rocket motor? 1. 8 2. 10 3. 12 4. 14 1-14. What precautions, if any, are used to ensure the correct rocket motor is installed on the proper seat? 1. Color coded tubes 2. Varied size motors 3. Varied size bolts 4. None 1-15. The rocket motor initiator has how many compartments? 1. One 2. Two 3. Three 4. Four 1-16. What is the main structural frame on the MK-GRUEA-7 ejection seat? 1. Catapult assembly 2. Main beam assembly 3. Rocket motor assembly 4. Cross-beam bracket 1-17. What component secures the seat in the aircraft? 1. Top latch mechanism 2. Time-release mechanism 3. Drogue gun assembly 4. Main beam assembly 1-18. The time-release mechanism provides auto- matic harness release separation at what altitude range? 1. 10,500 to 13,000 feet 2. 11,000 to 15,000 feet 3. 11,500 to 14,500 feet 4. 12,000 to 14,500 feet 1-19. What component provides visual indication of a properly installed MK-GRUEA-7 ejection seat? 1. Murphy-proof bracket 2. Top latch mechanism 3. Drogue gun assembly 4. Time-release mechanism 1-20. The SEAW ARS is designed to release the parachute from the crewmember during sea- water entry within how many seconds? 1. 1 2. 2 3. 3 4. 4 1-21. Which of the following is NOT a main assembly of the NACES? 1. Main beams 2. Catapult assembly 3. Parachute assembly 4. Rocket motor assembly 1-22. What component secures the NACES to the aircraft? 1. Main beams 2. Catapult assembly 3. Seat bucket assembly 4. Tie rods 1-23. Smooth movement of the seat bucket is provided by what component? 1. Seat bucket slippers 2. Roller bearings 3. Guide arms 4. Guide bushings 1-24. What component takes the full thrust of the catapult during ejection? 1. Inner tube 2. Outer tube 3. Main cross-beam 4. Top cross-beam 1-25. The seat structure is secured to the catapult by what component? 1. Top latch assembly 2. Inner tube 3. Outer tube 4. Interference arms 1-26. The drogue deployment catapult is mounted at what location? 1. Inboard of the RH main beam 2. Outboard of the RH main beam 3. Outboard of the center cross-beam 4. Inboard of the center cross-beam 2

1-27. What controls the firing of the drogue catapult? 1. Altitude 2. Airspeed 3. Time release mechanism 4. Electronic sequencer 1-28. What is the diameter of the drogue chute? 1. 36 in. 2. 48 in. 3. 57 in. 4. 72 in. 1-29. The PDRM is mounted at what location? 1. Underside of the parachute assembly 2. Left side of the main beam 3. Left side of the catapult 4. Right side of the catapult 1-30. Which of the following is NOT a component of the electronic sequencing system? 1. Two thermal couples 2. Two thermal batteries 3. Two pitot assemblies 4. Two sequencer start switches 1-31. The sequencer controls which of the following ejection events? 1. Canopy deployment 2. Seat deployment 3. Man/seat separation 4. Emergency oxygen activation 1-32. What component(s) supplies/y gas pressure to operate the underseat rocket motor? 1. Electronic sequencer 2. Time release mechanism 3. Catapult assembly 4. Multipurpose initiators 1-33. What component ensures the seat occupant is correctly positioned and locked in for ejection? 1. Shoulder harness reel 2. Lap belt assembly 3. Occupant retaining assembly 4. G-limiter assembly 1-34. Due to aircraft installation requirements, what different characteristics, if any, do the SJU-17(V)1/A, 2/A, and 9/A seat buckets have compared to the SJU-17(V)3/A thru 6/A as- semblies? 1. Different color 2. 1 inch wider 3. 1 inch taller 4. None 1-35. The underseat rocket motor has which of the following differences in features to prevent incorrect installation between forward and aft seats on the F-18 aircraft? 1. Angle alignments 2. Shear pin sizes 3. Mounting bolt sizes 4. Colors 1-36. The SAFE/ARMED handle shows what color when in the ARMED position? 1. Yellow and black 2. Black and red 3. Yellow and red 4. Red 1-37. What difference, if any, do the canopy penetrators on the forward seat have between the aft seats? 1. Width 2. Length 3. Color 4. None 1-38. How many different NACES seat bucket survival kit variations are there? 1. One 2. Two 3. Three 4. Four 1-39. The emergency oxygen system is auto- matically activated during ejection by what component or event? 1. Time release mechanism 2. Extension of a lanyard 3. Altitude reaches 5,000 feet 4. Altitude reaches 13,500 feet 1-40. What color are the manual deployment handles on the survival kit? 1. White 2. Green 3. Orange 4. Yellow 1-41. When the ejection control handle is pulled, the sears are withdrawn from the seat initiator firing mechanisms followed by what event? 1. Two impulse cartridges are fired 2. Electronic sequencer is activated 3. Time release mechanism is activated 4. Rocket motor initiates 3

1-42. During ejection, what component withdraws a piston from engagement in the lower operat- ing link of the emergency restraint release mechanism? 1. Rocket motor 2. Time delay mechanism 3. RH cartridge 4. LH cartridge 1-43. During ejection, what feature provides an even increase in gas pressure to eliminate excessive g-forces? 1. Telescopic design of the rocket 2. Delayed firing of the rocket cartridges 3. Tubular rings in the catapult 4. Staggered firing of the catapult cartridges 1-44. During ejection, once the leg restraint lines are freed from the aircraft, what component or condition restrains the remaining lines, pre- venting forward movement of the legs? 1. Harness locks 2. Snubbers 3. Negative g’s 4. Positive g’s 1-45. During ejection, sequencer timing commences during what condition? 1. Closure of the start switches 2. When the catapult reaches 23-inch exten- sion 3. When the catapult reaches 36-inch exten- sion 4. At 350 knots 1-46. When ejecting in MODE 3 between 500-600 keas, at what time interval does the sequencer fire the drogue deployment catapult? 1. 0.14 seconds 2. 0.22 seconds 3. 0.31 seconds 4. 0.33 seconds 1-47. When ejecting in MODE 1 between 0-300 keas, at what time interval does the sequencer fire the barostatic release unit cartridge and release harness locks? 1. 0.65 seconds 2. 1.30 seconds 3. 1.50 seconds 4. 3.10 seconds 1-48. When the ejection seat is fired, two onboard thermal batteries are immediately energized, supplying usable electrical power to the sequencer within what time frame? 1. 0.19 seconds 2. 0.23 seconds 3. 0.27 milliseconds 4. 100 milliseconds 1-49. At approximately what distance of seat travel are the two pyrotechnic cartridges actuated? 1. 18 inches 2. 24 inches 3. 32 inches 4. 42 inches 1-50. To maintain a uniform vertical acceleration profile on the seat and occupant, what component begins to operate just as the seat separates from the catapult? 1. Underseat rocket motor 2. Time delay mechanism 3. Sequencer start switch 4. Altitude sensor 4

5 ASSIGNMENT 2 Textbook Assignment: Chapter 3 – Canopy Systems and Chapter 4 – Explosives Handling Personnel Qualification and Certification Program 2-1. On the F-14 aircraft, what force provides normal opening and closing of the canopy? 1. Electric 2. Manual 3. Hydraulic 4. Pneumatic 2-2. The externally serviced reservoirs that supply power for the different modes of canopy operation contain what type of pressure? 1. Freon 2. Hydraulic 3. Oxygen 4. Pneumatic 2-3. How many acrylic panels make up the F-14 canopy? 1. One 2. Two 3. Three 4. Four 2-4. What locks the canopy in the closed position? 1. Locking hooks 2. Detent pins 3. Clevis bolts 4. Metal straps 2-5. What component actually opens and closes the canopy? 1. Pneumatic actuator 2. Piston assembly 3. Hydraulic actuator 4. Hydraulic valve 2-6. What component locks and unlocks the canopy? 1. Lock actuator restrictor 2. Canopy lock pneumatic actuator 3. Canopy hydraulic actuator 4. Canopy lock and unlock switch 2-7. What is the function of the lock actuator restrictor? 1. To lock the canopy in the open position 2. To lock the canopy in the closed position 3. To prevent inadverdent closing of the canopy 4. To regulate the speed during locking and unlocking of the canopy 2-8. The canopy pneumatic control module contains how many pressure reducers? 1. One 2. Two 3. Three 4. Four 2-9. The canopy pneumatic reservoir is serviced to what maximum pressure? 1. 1,000 psi 2. 2,000 psi 3. 3,000 psi 4. 3,500 psi 2-10. What is the total cubic inch capacity of the canopy pneumatic reservoir? 1. 225 2. 275 3. 325 4. 375 2-11. The reservoir relief valve opens at what minimum pressure? 1. 2,500 psi 2. 3,200 psi 3. 4,500 psi 4. 4,700 psi 2-12. The auxiliary pneumatic reservoir is serviced to what maximum pressure? 1. 1,500 psi 2. 2,000 psi 3. 3,000 psi 4. 3,500 psi 2-13. What component reduces pneumatic pressure to the auxiliary unlock pneumatic release valve? 1. Auxiliary bypass valve 2. Auxiliary pressure reducer 3. Auxiliary check valve 4. Auxiliary flow valve 2-14. How many ports are there on the unlock shuttle valve? 1. One 2. Two 3. Three 4. Four

6 2-15. What component prevents nitrogen from venting overboard? 1. Auxiliary pressure reducer 2. Unlock pneumatic release valve 3. Unlock shuttle valve 4. Lock actuator check valve 2-16. How many control handles are there for use in canopy operation? 1. One 2. Two 3. Three 4. Four 2-17. Which of the following is NOT a method of canopy operation? 1. Emergency mode 2. Holding mode 3. Boost closing mode 4. Normal opening mode 2-18. During normal opening mode, the shutoff valves in the open and close modules are vented to atmosphere through what port of the actuator? 1. C5 2. C2 3. C3 4. C4 2-19. During normal opening mode, nitrogen on the opposite side of the piston is vented overboard through what valve of the control module? 1. No. 5 2. No. 2 3. No. 3 4. No. 4 2-20. During the BOOST closing mode, valve no. 4 in the control module is positioned to direct what maximum pressure through the C2 port? 1. 475 psi 2. 560 psi 3. 645 psi 4. 790 psi 2-21. After 3 minutes in BOOST closing mode, the nitrogen pressure will decrease to what minimum pressure on a system serviced to 3,000 psi? 1. 1,000 psi 2. 800 psi 3. 600 psi 4. 500 psi 2-22. When should you use the auxiliary opening mode to unlock the canopy? 1. No electrical power 2. Anytime 3. Pneumatic system pressure drops below 225 psi 4. Emergency 2-23. What air source is used to inflate the canopy seal system? 1. Cooled engine bleed air 2. Vented cabin air 3. Ram air 4. Ambient air 2-24. Where is the canopy seal pressure regulator located? 1. Under the pilot’s seat 2. In the nose wheelwell 3. In the port wheelwell 4. On the turtledeck 2-25. The canopy pressure seal receives cooled engine bleed air at approximately what pressure? 1. 40 psi 2. 60 psi 3. 80 psi 4. 100 psi 2-26. How many types of pyrotechnic cords are used in the F-14 canopy emergency jettison system? 1. One 2. Two 3. Three 4. Four 2-27. The term XSMDC stands for what type of pyrotechnic cord? 1. Explosive shielded mild detonating cord 2. Expanding shielded mild detonating cord 3. Extreme shielded mild detonating cord 4. Extra shielded max detonating cord 2-28. What component prevents the explosive signal provided by the canopy jettison initiator from entering the SMDC lines of the seat ejection system? 1. One-way explosive transfer 2. Manifold check valve 3. Jettison relief valve 4. SMDC relief valve

7 2-29. The S-3 frangible escape system uses what type of explosives instead of hot gas? 1. SMDC 2. FSDC 3. MK 90 4. MK 53 2-30. Instead of safety pins, the external jettison handle uses what item to protect from inadvertent firing? 1. Clevis bolts 2. Safety guard 3. 10-foot lanyard 4. Trigger switch lock 2-31. The window-severance explosive charge is actuated by what crewmember(s)’s initiator? 1. TACCO 2. Pilot only 3. Copilot only 4. Either the pilot or copilot 2-32. Why is an SMDC explosive system more favorable than a hot gas system? 1. Cost effective 2. More reliable 3. Slower 4. Higher initiating pressure 2-33. Which of the following was a factor in the ordnance mishap onboard the USS ORISKANY? 1. Faulty ordnance 2. Faulty maintenance 3. Lack of training 4. Fatigue 2-34. DELETED 2-35. What instruction governs the Qual/Cert program? 1. OPNAVINST 8020 2. OPNAVINST 9600.2 3. NAVAIR 11-100-1 4. NAVAIR 11-85-1 2-36. What term refers to the physcial act of transporting or moving explosives/explosive devices afloat or ashore? 1. Storage/stowage 2. Handling 3. Load/download 4. Assembly/disassembly 2-37. Which of the following individuals may NOT sign as board chairman on the ordnance certification form? 1. CO 2. OIC 3. Division officer 4. XO 2-38. DELETED 2-39. Which of the following is required on the ordnance certification form when an individual certification is revoked? 1. Revoked stamped in red on form 2. Signature of individual in red pen 3. Signature of board chairmen in red pen 4. Diagonal red line on Qual/Cert form 2-40. DELETED 2-41. The Qual/Cert program is NOT applicable to which of the following personnel? 1. Security force 2. Contractors 3. Civilians 4. EOD 2-42. What individual may revoke certification? 1. CO 2. XO 3. MO 4. LPO 2-43. What is required when an explosive mishap is caused by an individual’s failure to follow authorized procedures? 1. Reduction in paygrade 2. Forfeiture of pay 3. Page 13 record entry 4. Assignment to administrative duties 2-44. Qual/Cert is valid for how many years? 1. 1 2. 2 3. 3 4. 4 2-45. In the Qual/Cert program, which of the following individuals must the CO certify in writing? 1. Certification board members 2. Team members 3. Team leaders 4. All of the above

8 2-46. The Qual/Cert board consists of which of the following individuals? 1. Department head 2. At least two E-7 and above personnel 3. Quality assurance representative 4. LPO 2-47. If seniority requirements cannot be met on the Qual/Cert board within a command, what activity may grant a waiver? 1. CNO 2. Local wing 3. TYCOM 4. NAVAIR

ASSIGNMENT 3 Textbook Assignment: Chapter 5 – Utility Systems 3-1. Which of the following systems does NOT get its air from an auxiliary bleed air system? 1. Air-conditioning 2. Pressurization 3. Anti-icing 4. Liquid oxygen 3-2. A bleed air system can reach up to what tem- perature? 1. 100°F 2. 250°F 3. 375°F 4. 400°F 3-3. An S-3 aircraft bleed air leak detection system consists of how many loops? 1. 5 2. 2 3. 3 4. 4 3-4. The sensing elements for a bleed air leak detec- tion system are mounted between ducts and the aircraft structure for what reason? 1. The bleed air temperature is high 2. The bleed air temperature is low 3. The clearance is greater 4. The accessibility is greater 3-5. In a bleed air leak detection system, what causes a chemical reaction in the sensing element? 1. Humidity 2. Moisture 3. Heat 4. Pressure 3-6. An S-3 bleed air leak detection system is powered by what bus? 1. Essential ac 2. Essential dc 3. Auxiliary generator 4. 200-Hz 3-7. During a test of an S-3 bleed air leak detection system, a ground circuit is completed to turn on which of the following lights? 1. 1A BL LEAK 2. 2 BL LEAK 3. FLT LB LEAK 4. AUX BL LEAK 3-8. Which of the following is NOT a component of a bleed air leak detection system? 1. Leak detector control 2. Sensing elements 3. Flow valves 4. Engine start port leak detector 3-9. Bleed air sensing elements are mounted within what distance of ducts? 1. 1-2 inches 2. 1-3 inches 3. 2-5 inches 4. 2-8 inches 3-10. The engine start port leak detector completes a ground circuit in excess of what temperature? 1. 150°F 2. 175°F 3. 200°F 4. 225°F 3-11. What type of ice on aircraft surfaces is smooth and hard to detect visually? 1. Glazed 2. Rime 3. Black 4. Clear 3-12. Frost is a result of which of the following factors? 1. Ice crystals are oxidized 2. The air is thin 3. The air is heavy 4. Water vapor is turned into a solid 9

3-13. Which of the following systems is designed to remove ice after it has formed? 1. Deice boot system 2. Anti-ice system 3. Removal ice system 4. Hot air system 3-14. A P-3 aircraft gets its air source for anti-icing from what stage of an engine compressor? 1. 10th 2. 12th 3. 14th 4. 16th 3-15. A P-3 aircraft ice detector warning light is located where? 1. Pilot’s instrument panel 2. Copilot’s instrument panel 3. Center instrument panel 4. Monitorial ac bus panel 3-16. The shutoff valve for a wing deice system has an indicator to show valve position. Where is this indicator located? 1. In the nosewheel well 2. In the flight station indicator gauge 3. On the valve flywheel 4. On top of the valve housing 3-17. What component controls the valve opening for an anti-ice modulating valve? 1. Thermostat 2. Overheat caution circuit 3. Plenum probe 4. Modulating valve sensor 3-18. The thermostats in the outboard leading edge plenum areas are set at what temperature? 1. 95°F 2. 110°F 3. 125°F 4. 145°F 3-19. The wing inboard and center section thermostat are set at what temperature? 1. 120°F 2. 140°F 3. 160°F 4. 180°F 3-20. The airfoil temperature sensor amplifier is powered by what component? 1. LEAD EDGE TEMP 2. LE HOT 3. OVHT W ARNING 4. WING LEADING EDGE SKIN 3-21. High temperature within the leading edge is generally caused by which of the following conditions? 1. Faulty probe 2. Faulty modulator valve 3. Condensation 4. Humidity 3-22. Which of the following positions is NOT a selection for the ice protection panel rotary switch? 1. INBD 2. CTR 3. OUTBD 4. WING 3-23. The OPEN light on the ice protection panel illuminates when what condition occurs? 1. Bleed air valve opens 2. Modulating valve opens 3. Thermostat opens 4. Overheat in wing occurs 3-24. The fuselage bleed air shutoff valves are normally in what position during normal deicing operation? 1. Fully open 2. Open 2 degrees 3. Open 8 degrees 4. Closed 3-25. When performing a leak test on the anti-ice system, the time delay relay will illuminate the ACCEPT light after how many seconds? 1. 6 2. 8 3. 10 4. 12 3-26. The warm air temperature control valve for a windshield anti-ice system is modulated by what type of force? 1. Hydraulic 2. Electrical 3. Muscle 4. Suction 10

3-27. The flow/temperature limiting anti-ice valve is what type of valve? 1. Single function 2. Dual function 3. Temperature sensitive 4. Manual 3-28. The warm air over temperature sensor opens if duct temperature reaches what temperature, ±25°F? 1. 200°F 2. 250°F 3. 325°F 4. 375°F 3-29. The windshield overheat temperature sensor closes when airflow drops to what tem- perature? 1. 225°F ±5°F 2. 280°F ±5°F 3. 320°F ±10°F 4. 380°F ±10°F 3-30. The windshield anti-ice/rain removal switch has how many positions? 1. One 2. Two 3. Three 4. Four 3-31. An EA-6B aircraft windshield washing system uses what percentage of methyl alcohol? 1. 50 percent 2. 20 percent 3. 30 percent 4. 40 percent 3-32. The EA-6B windshield washing system has how many nozzles? 1. 5 2. 6 3. 7 4. 8 3-33. What component is NOT a part of the windshield washing shutoff valve? 1. Pressure reducer 2. Check valve 3. Dump valve 4. Temperature solenoid 3-34. When the windshield washing shutoff valve is energized, how much air pressure is regulated to the windshield washing tank? 1. 8 ±1 psig 2. 10 ±1 psig 3. 13 ±0.5 psig 4. 15 ±1 psig 3-35. The windshield switch is what type of switch? 1. Single-pole, two-position 2. Single-pole, three-position 3. Double-pole, two-position 4. Double-pole, three-position 3-36. Holding the WINDSHIELD switch to W ASH routes what amount of voltage to open the shutoff valve? 1. 20 Vdc 2. 24 Vdc 3. 28 Vdc 4. 32 Vdc 3-37. The anti-g internal relief valve maintains what maximum pressure? 1. 5 psi 2. 7 psi 3. 9 psi 4. 11 psi 3-38. Pressing the button on top of an anti-g valve performs which of the following functions? 1. Manually operates the anti-g valve 2. Closes the anti-g valve 3. Causes emergency shutdown of system 4. Releases hose assembly 3-39. Where is the vent suit temperature sensor located? 1. Downstream of the vent suit regulating valve 2. Downstream of the heat exchanger 3. Upstream of the vent suit valve 4. Downstream of the vent suit valve 3-40. The vent suit pressure regulating valve limits flow rate to how many cfm? 1. 10 2. 14 3. 18 4. 22 11

3-41. The vent suit pressure relief valve begins to open at what pressure? 1. 10 psi 2. 12 psi 3. 16 psi 4. 18 psi 3-42. The vent suit pressure relief valve is fully open at what pressure? 1. 12 psi 2. 15 psi 3. 18 psi 4. 21 psi 3-43. How is the radar liquid cooling system airflow valve operated? 1. Electrically 2. Manually 3. Hydraulically 4. Pneumatically 3-44. Which of the following is NOT a characteristic of CF 3BR? 1. Odorless 2. Tasteless 3. Toxic 4. Non-corrosive 3-45. The ram air scoop for the radar liquid cooling system closes from a signal from what com- ponent? 1. Air data computer 2. Airflow valve 3. Liquid coolant pump 4. Scoop controller 3-46. The P-3 fire extinguisher container assembly is pressurized with what amount of nitrogen? 1. 400 psi 2. 600 psi 3. 800 psi 4. 875 psi 3-47. A safety disc plug on the fire extinguisher container has a burst range of what pressure? 1. 1000 to 1350 psi 2. 1450 to 1800 psi 3. 1850 to 2000 psi 4. 2050 to 2200 psi 3-48. When operating the APU TEST switch, which of the following is an indication that the system is working properly? 1. Horn sounds 2. Gauge fluctuates 3. Warning light goes off 4. Circuit switch is energized 3-49. The avionics pressurization filter removes what percentage of particles larger than 10 microns? 1. 88 percent 2. 93 percent 3. 95 percent 4. 98 percent 3-50. A waveguide air desiccator turns what color when moisture is present? 1. Blue 2. Red 3. Pink 4. White 3-51. The missile cold air modulating valve receives electrical signals from what component? 1. Heat exchanger 2. Solenoid motor 3. Temperature valve 4. Missile controller 3-52. A pressure switch on the missile coolant pump opens when the output pressure drops to which of the following pressures? 1. 35 psi 2. 48 psi 3. 62 psi 4. 72 psi 12

13 ASSIGNMENT 4 Textbook Assignment: Chapter 6 – Air-Conditioning and Pressurization Systems 4-1. At 18,000 feet, the density of the Earth’s atmosphere is about what amount compared to that at sea level? 1. One-quarter 2. One-half 3. Three-quarters 4. No difference 4-2. What is the atmospheric pressure at sea level? 1. 9.7 psi 2. 12.2 psi 3. 14.7 psi 4. 14.9 psi 4-3. What is the atmospheric pressure at 60,000 feet? 1. 1 psi 2. 2 psi 3. 3 psi 4. 4 psi 4-4. At approximately 37,000 feet, what is the outside air temperature? 1. –65°C 2. –55°C 3. –30°C 4. –20°C 4-5. The lowest outside air temperature that an aircraft can encounter could occur at what height? 1. 10,000 feet 2. 20,550 feet 3. 32,650 feet 4. 37,000 feet 4-6. An aircraft flying at supersonic speed at an altitude of 35,000 feet may generate what temperature on its skin? 1. 120°F 2. 200°F 3. 280°F 4. 320°F 4-7. Which of the following is NOT a heat source that will raise cabin/cockpit temperature? 1. Solar heat 2. Heat from electrical units 3. Body heat 4. Aileron heat 4-8. Experiments have proven that a person can withstand and maintain efficiency for extended periods at what maximum temperature? 1. 80°F 2. 87°F 3. 92°F 4. 98°F 4-9. How many requirements are there for the successful functioning of a pressurization and air- conditioning system? 1. 6 2. 5 3. 3 4. 4 4-10. On all jet aircraft, the air used for an ECS is taken from what section of the jet engine? 1. Turbine 2. Fan 3. Compressor 4. Inlet 4-11. The cooling of bleed air before it enters the cabin is provided by what component? 1. Discharge valve 2. Bleed air cooling valve 3. Bleed air mixture unit 4. Refrigeration unit 4-12. The term air-to-air comes from the principle of cooling the air without the use of what component or additive? 1. Compressors 2. Cooling valves 3. Refrigerants 4. Antifreeze 4-13. A P-3 air-conditioning system is comprised of how many independent air cycle cooling systems? 1. One 2. Two 3. Three 4. Four

14 4-14. Which of the following components is a fresh air source for a P-3 ACS? 1. AMP 2. Bleed valve 3. Turbine shutoff valve 4. Refrigeration cooling valve 4-15. EDCs are what type of compressor units? 1. Single stage 2. Dual stage 3. Multi-stage 4. Manual stage 4-16. What component is the primary air source for the ACS during static ground operations? 1. Refrigeration unit 2. No. 2 engine 3. No. 3 engine 4. AMP 4-17. The EDCs are adjusted for a maximum power requirement of what horsepower? 1. 69 hp 2. 76 hp 3. 81 hp 4. 94 hp 4-18. The air volume in the APU/AMP divides at what section? 1. Distribution duct 2. Spread out duct 3. Outflow duct 4. ACS interconnection duct 4-19. When the APU/AMP is the air supply source, what component is used to balance airflow? 1. Equalizer valve 2. Flow-limiting venturi 3. Combination valve 4. Back-pressure valve 4-20. What component in the ACS removes moisture from the air prior to its entering the cabin? 1. Water separator 2. Water remover 3. Water extractor 4. Water drain 4-21. The flow-limiting venturi is sized to limit airflow to what amount per minute? 1. 32 pounds 2. 43 pounds 3. 56 pounds 4. 67 pounds 4-22. On a flow-limiting venturi, reverse EDC airflow is prevented by what component? 1. Block off plate 2. Mesh screen 3. Check valve 4. Reverse valve 4-23. Which of the following is NOT a component of a cabin temperature control system? 1. Master temp sensor 2. Duct rate sensor 3. Control temp sensor 4. Ice-limiting sensor 4-24. The temperature control system selector-indicator has how many sets of dot markings? 1. One 2. Two 3. Three 4. Four 4-25. Rotating the push-pull knob counterclockwise on the selector-indicator performs what function? 1. Provides cooler air 2. Provides warmer air 3. Increases airflow 4. Decreases airflow 4-26. The temperature controller is composed of what number of modules? 1. One 2. Two 3. Three 4. Four 4-27. What component in the temperature controller controls the automatic mode control circuitry? 1. Selector amplifier 2. Automatic amplifier 3. Programming amplifier 4. Passive amplifier 4-28. The cabin master temperature sensor is at what location? 1. Above pilot 2. Above copilot 3. Above sensor operator 4. Above TACCO 4-29. Elimination of EDC back-pressure is provided by what component? 1. Pressure ratio limiter 2. Ice limiter 3. Back-pressure valve 4. Relief valve

15 4-30. The pressure ratio limiter is intended to function at what altitude? 1. Below 10,000 feet 2. Between 11,200 and 13,300 feet 3. Between 12,600 and 14,800 feet 4. Above 18,000 feet 4-31. In order for aircrew personnel to operate at the same level of efficiency as at sea level, what solution was developed? 1. Increasing oxygen capacity 2. Pressurizing the cockpit/cabin area 3. Modifying outflow valve 4. Modifying air-to-air system 4-32. The area of an aircraft that is pressurized must be free from which of the following things? 1. FOD 2. Personnel 3. Heated components 4. Air leaks 4-33. The S-3 pressurization system regulates what type of air to control cabin pressure? 1. Inflow 2. Outflow 3. Pneumatic 4. Pressurized 4-34. The S-3 pressurization system consist of how many modes of operation? 1. Five 2. Two 3. Three 4. Four 4-35. Which of the following is NOT a mode of pressurization operation? 1. Unpressurized 2. Isobaric 3. Dump 4. Constant 4-36. At a flight altitude of 15,000 feet, what is the minimum cabin pressure differential? 1. 3.02 psi 2. 3.56 psi 3. 3.94 psi 4. 4.19 psi 4-37. At a flight altitude of 25,000 feet, what is the maximum cabin pressure altitude? 1. 5,000 feet 2. 5,380 feet 3. 5,600 feet 4. 5, 869 feet 4-38. At a flight altitude of 40,000 feet, what is the minimum cabin pressure altitude? 1. 8,340 feet 2. 9,600 feet 3. 11,520 feet 4. 12,050 feet 4-39. During flight operations between 5,000 and 24,000 feet, what mode of operation is in effect? 1. Unpressurized 2. Isobaric 3. Differential 4. Repressurization 4-40. The differential mode of operation overrides the isobaric mode when the aircraft is flying in excess of what altitude? 1. 10,000 feet 2. 14,000 feet 3. 18,000 feet 4. 24,000 feet 4-41. During the dump mode of operation, the re- circulation valve is actuated to what position? 1. 45° open 2. 65° open 3. Full open 4. Closed 4-42. The repressurization mode of operation is used for what purpose? 1. When returning from the dump mode 2. When returning from the isobaric mode 3. When returning from the differential mode 4. To close the outflow valve 4-43. The S-3 pressurization system will begin to pressurize whenever the ground elevation is above what altitude? 1. 2,300 feet 2. 3,200 feet 3. 4,000 feet 4. 5,000 feet

16 4-44. To ensure adequate cooling of the avionics system during ground operations at altitudes above 5,000 feet, which of the following is a step that must be adherred to? 1. Set CABIN PRESS to isobaric mode 2. Set CABIN PRESS to flight mode 3. Turn AUX VENT selector to ON 4. Turn OUTFLOW selector to OFF 4-45. How is the cabin pressure regulator valve actuated? 1. Pneumatically 2. Hydraulically 3. Electrically 4. Manually 4-46. How many ports lead into the pressure regulator valve diaphragm chamber? 1. One 2. Two 3. Three 4. Four 4-47. Which of the following is NOT a position on the cabin pressure regulator control? 1. ALL OFF 2. AUX 3. FLIGHT 4. DIFF ON 4-48. The cabin pressure regulator control has how many pneumatic ports? 1. One 2. Two 3. Three 4. Four 4-49. The cabin low-pressure switch closes at what altitude? 1. 11,000 (±500) feet 2. 12,000 (±250) feet 3. 13,000 (±500) feet 4. 14,000 (±250) feet 4-50. The cabin air pressure sensing filter traps dust particles greater than what minimum diameter? 1. 2 microns 2. 4 microns 3. 8 microns 4. 10 microns

ASSIGNMENT 5 Textbook Assignment: Chapter 7 – Oxygen Systems 5-1. A minimum of 50 psi must be maintained in a gaseous oxygen supply cylinder. What could be the result of not maintaining this pressure? 1. The oxygen regulators would not function properly 2. The crewmember’s mask would not function properly 3. Cockpit odors would be allowed to enter the oxygen cylinders 4. Moisture would be allowed to accumulate in the cylinders 5-2. Personnel servicing or maintaining oxygen sys- tems and components must be very careful to protect systems from which of the following substances? 1. Grease and oil 2. Hydraulic fluid 3. Both 1 and 2 4. Type 1 trichlorotrifluoroethane 5-3. All high-pressure oxygen cylinders are painted what color in accordance with the established color codes? 1. Gray 2. Green 3. Blue 4. Yellow 5-4. Oxygen cylinder valves are equipped with a safety plug filled with a fusible metal designed to melt within what temperature range? 1. 190°F to 207°F 2. 208°F to 220°F 3. 222°F to 245°F 4. 246°F to 270°F 5-5. The self-opening (automatic) oxygen cylinder valve is automatically opened under what conditions? 1. When the pilot inhales 2. When a lever is positioned to ON 3. When the pressure is over 500 psi 4. When it is connected to the oxygen line 5-6. Which of the following regulator maintenance tasks are NOT performed by AMEs? 1. Removal 2. Installation 3. Repairs 4. Operational checks 5-7. The tubing used in aircraft high-pressure oxy- gen systems is made from which of the following types of material? 1. Copper 2. Steel 3. Bronze 4. Cadmium 5-8. What lines run from the oxygen cylinders to the regulators? 1. Filler 2. Cylinder 3. Regulator 4. Distribution 5-9. Oxygen lines are identified by strips of what color paint and/or tape? 1. White paint 2. Green paint 3. Green and white tape 4. Blue and white tape 5-10. For which of the following connections is high-pressure tubing NOT used? 1. The cylinder valve and the regulator inlet in high-pressure systems 2. The cylinder valve and the pressure reducer in reduced high-pressure sys- tems 3. The pressure reducer and the outlets in reduced high-pressure systems 4. The oxygen cylinder valve and the filler connection in both high- and low-pressure systems 17

5-11. Adapters and fittings are connected to the ends of copper tubing in high-pressure oxygen systems in what manner? 1. Silver soldered 2. Flared 3. Electric arc welded 4. Tin and lead soldered 5-12. If a line in a gaseous oxygen system ruptures, the loss of the entire oxygen supply is prevented by which of the following valves? 1. Filler 2. Check 3. Shutoff 4. Pressure-reducing 5-13. Check valve castings have arrows embossed on them to provide what information? 1. The direction of the master oxygen supply 2. The direction of the flow through the valve 3. The section of the valve to be mounted facing aft 4. The section of the valve to be mounted facing forward 5-14. In some oxygen systems, high cylinder pres- sure is changed to a low working pressure by which of the following valves? 1. Pressure-reducing 2. Manifold control 3. Cylinder control 4. Filler control 5-15. Pressure reducers are always in what location? 1. Oxygen distribution lines 2. Cylinder outlet caps 3. Filler valve inlets 4. Regulator outlets 5-16. What valve, located within the common filler valve, opens during the oxygen system filling operation and closes when filling is complete? 1. Regulator 2. Shutoff 3. Check 4. Pressure-reducing 5-17. If the pressure gauge on a 500 psi low-pressure system indicates 125 psi, what fractional part of the oxygen is left? 1. One-fourth 2. One-half 3. Two-thirds 4. Three-fourths 5-18. High-pressure gaseous oxygen system pres- sure gauges mounted at each flight station are calibrated to indicate pressure ranging from 0 to what maximum pressure? 1. 500 psi 2. 1,500 psi 3. 1,800 psi 4. 2,000 psi 5-19. In the reduced high-pressure oxygen system, a malfunctioning pressure reducer will be indicated by which of the following actions? 1. Rapid decline of quantity on the quantity gauge 2. Illumination of the low quantity light 3. Both 1 and 2 4. Rupture of the green disc in the discharge indicator 5-20. What items or devices should be used as a handle to carry the portable oxygen walkaround unit? 1. Regulator 2. Straps 3. Breathing tube 4. Copper tubing 5-21. Liquid oxygen will remain a liquid under normal atmospheric pressure at what minimum temperature? 1. –182°F 2. –220°F 3. –297°F 4. –320°F 5-22. What is the expansion ratio of liquid oxygen to gaseous oxygen? 1. 962:1 2. 862:1 3. 782:1 4. 692:1 5-23. The combustion-supporting potential of oxy- gen is a greater danger than freezing. 1. True 2. False 18

5-24. When transferring LOX from one container to another, which of the following precautions should be taken? 1. Pour slowly to avoid splashing the liquid out of the container 2. Pour slowly to allow the receiving receptacle to cool sufficiently without thermal breakage 3. Both 1 and 2 4. Minimize LOX from venting into the atmosphere by pouring as rapidly as pos- sible 5-25. How many psi of pressure will LOX generate if it is allowed to evaporate at atmospheric pressure in a sealed container that has no relief provisions? 1. 10,000 psi 2. 12,000 psi 3. 14,000 psi 4. 16,000 psi 5-26. The pressure relief assembly in a LOX system storage vessel consists of which of the follow- ing items? 1. A rupture disc 2. A reseatable relief valve 3. Both 1 and 2 above in series 4. Both 1 and 2 above in parallel 5-27. Which of the following statements is correct concerning the stowage of LOX containers? 1. Hydrocarbons in the vicinity of stowed LOX containers do not present a hazardous condition 2. LOX containers should not be stowed in the vicinity of flammable gases or liquids 3. Because of the insulation in LOX con- tainers, open outside stowage is desirable 4. Stowage of LOX containers must be in refrigeration spaces 5-28. When dealing with LOX leakage or spillage, which of the following actions should be taken? 1. Immediately mop up the LOX and hose down with water 2. Immediately hose the area with water 3. Dilute the LOX with a caustic soda and hose down with water 4. Ventilate the leakage or spillage to allow LOX to evaporate into the atmosphere 5-29. What action should be taken when an article of clothing you are wearing comes in contact with LOX? 1. Separate the article of clothing from skin contact immediately, and thoroughly air clothing to allow dilution of the oxygen 2. Apply large quantities of water to the clothing area that has come in contact with the LOX 3. Remove the contaminated article of cloth- ing and discard 4. Remove the contaminated article of cloth- ing for washing 5-30. For what reason must a completely empty aircraft LOX converter be serviced slowly? 1. To allow the system to be completely filled 2. To prevent possible damage to the converter by thermal shock 3. To allow the safety valves in the system time to adjust to the servicing 4. To prevent the thermal relief valve from operating prematurely 5-31. What is the advantage of using liquid oxygen systems over gaseous oxygen systems on aircraft? 1. Liquid systems are less dangerous 2. One LOX converter replaces several of gaseous oxygen 3. Liquid systems are more efficient 4. Liquid oxygen is more economical to manufacture 5-32. An explosion could occur if a leak should develop in the inner shell of a LOX converter. Which of the following components prevents an explosion from occurring? 1. Pressure isolating valve 2. Two-way check valve 3. Filler valve 4. Blowout disc 5-33. During servicing of an aircraft LOX system, a means for venting is needed. What valve in the oxygen system provides this venting? 1. Filler valve 2. Pressure relief valve 3. Vent valve 4. Spring-loaded check valve 19

5-34. What is the purpose of the heat exchanger in a LOX system? 1. To cool the LOX leaving the servicing cart to prevent damage to the aircraft’s LOX converter 2. To increase the temperature of the LOX leaving the aircraft’s converter 3. To prevent damage to the lungs of the crewmember breathing the oxygen 4. To convert the LOX to gaseous oxygen 5-35. What is the purpose of the low-pressure switch in an aircraft’s oxygen supply line? 1. To operate the oxygen caution light 2. To cut off oxygen servicing when the air- craft system is full 3. To warn personnel servicing the aircraft that the system is approaching full 4. To complete the electrical circuit to the LOX quantity indicator 5-36. How does a crewmember know when the LOX system is in a low state? 1. By checking the quantity indicator 2. By the illumination of a low quantity light 3. By both 1 and 2 4. By checking the oxygen pressure gauge 5-37. What is incorporated in the LOX system to protect the pressure regulator and crewmember from excessive pressure should the LOX con- verter malfunction? 1. A thermal expansion valve located be- tween the LOX converter and the oxygen regulator 2. A thermal expansion valve located in the LOX converter 3. A relief valve located in the LOX converter 4. A relief valve located in the oxygen shutoff valve 5-38. Which of the following types of tubing is used in LOX systems aboard aircraft? 1. Low-pressure aluminum alloy 2. High-pressure aluminum alloy 3. Low-pressure stainless steel 4. High-pressure stainless steel 5-39. Which of the following type of aircraft would use a miniature oxygen regulator? 1. P-3 2. C-130 3. F-18 4. MH-53 5-40. The miniature oxygen regulator will deliver 100 percent oxygen automatically when the inlet pressure does not exceed what psi? 1. 120 psi 2. 130 psi 3. 140 psi 4. No pressure limitations; will deliver 100 percent at any psi 5-41. What is the operating pressure of the MD-1 regulator? 1. 0 to 500 psi 2. 50 to 500 psi 3. 0 to 2000 psi 4. 50 to 2000 psi 5-42. Oxygen flow on an MD-type regulator is indicated by what type of action? 1. Fluctuation quantity gauge 2. Light illuminated 3. Horn sounded 4. Blinking action on FLOW indicator 5-43. Which of the following is NOT a toggle position on the emergency pressure control lever of an MD-2 regulator? 1. EMERGENCY 2. NORMAL 3. 100% OXYGEN 4. TEST MASK 5-44. On an MD-type regulator, at what minimum altitude will the regulator provide 100 percent oxygen? 1. 15,000 feet 2. 23,000 feet 3. 28,000 feet 4. 33,000 feet 5-45. An MD-type regulator is protected against overpressure by what component? 1. First stage relief valve 2. Second stage relief valve 3. Flow limiting valve 4. Overpressure valve 5-46. Which of the following is NOT a probable cause if the panel light on an MD-1 regulator fails? 1. Burned out lamp 2. Over-serviced system 3. Faulty light assembly 4. Faulty electrical hookup to power source 20

5-47. The buildup sequence on a LOX converter begins when what action occurs? 1. The filler hose is removed from the con- verter 2. The filler hose is connected to the con- verter 3. Pressure reaches 100 psi 4. Pressure drops to 50 psi 5-48. At approximately what pressure will the pressure-opening valve unseat and allow gaseous oxygen to flow from the converter to the supply system? 1. 32 psi 2. 50 psi 3. 63 psi 4. 82 psi 5-49 Scheduled preventive maintenance for an OBOGS occurs at what time interval? 1. 28 days 2. 256 days 3. 2000 hours 4. 3000 hours 5-50. Which of the following is a position on an OBOGS control panel assembly? 1. OXY FLOW 2. 100% OXYGEN 3. STANDBY 4. EXHAUST 21

22 ASSIGNMENT 6 Textbook Assignment: Chapter 8 – Oxygen Support Equipment 6-1. Open flames and smoking should be kept what minimum distance from a LOX handling area? 1. 10 feet 2. 25 feet 3. 35 feet 4. 50 feet 6-2. What may occur, if anything, if LOX is mixed with gasoline, kerosene, oil, or other hydrocarbons? 1. Spontaneous ignition 2. Strong odor 3. High fume content 4. Nothing will happen 6-3. What type of LOX system was developed to eliminate the safety hazards of venting oxygen? 1. Low loss, open loop 2. Low loss, closed loop 3. High loss, closed loop 4. High loss, open loop 6-4. What is the capacity of the transfer tank for the TMU-70/M? 1. 25 liters 2. 15 liters 3. 25 gallons 4. 15 gallons 6-5. What it the primary purpose of the TMU-70/M LOX cart? 1. To store LOX 2. To convert LOX to gaseous oxygen 3. To service oxgyen bottles 4. To service LOX converters 6-6. On the TMU-70/M, the vented oxygen vapors are returned to what component? 1. Transfer tank 2. Transfer lines 3. Storage tank 4. Storage lines 6-7. The storage tank on the TMU-70/M is what type of walled system? 1. Single 2. Double 3. Titanium 4. Vacuum cooled 6-8. The safe operating pressure on the storage tank pressure gauge is indicated by what psi? 1. 0 to 25 psi 2. 0 to 50 psi 3. 0 to 75 psi 4. 0 to 100 psi 6-9. On the TMU-70/M, what component indicates the level of liquid oxygen in the inner tank? 1. Storage tank pressure gauge 2. Storage tank oxygen gauge 3. Storage tank liquid pressure gauge 4. Storage tank liquid level gauge 6-10. What component controls the flow of oxygen gas vapors from the transfer tank to the vapor space of the storage tank? 1. Transfer tank vent line shutoff valve 2. Transfer tank fill line shutoff valve 3. Transfer tank pressure buildup valve 4. Converter vent line shutoff valve 6-11. On the TMU-70/M, what component controls the flow of oxygen from the bottom of the transfer tank to the pressure buildup coil? 1. Transfer tank vent line shutoff valve 2. Transfer tank fill line shutoff valve 3. Transfer tank pressure buildup valve 4. Converter vent line shutoff valve 6-12. The transfer tank pressure gauge is indicated by a green band and what psig reading? 1. 0 to 30 psig 2. 0 to 60 psig 3. 0 to 90 psig 4. 0 to 120 psig

23 6-13. During transfer of liquid to a converter, the converter full indicator gauge displays what reading? 1. Gas 2. Liquid 3. Servicing 4. Full 6-14. During filling, the fill-drain line shutoff valve is set in what position? 1. Liquid 2. Gas 3. Open 4. Closed 6-15. Controlling the release of gaseous vapors from the storage tank to the vent piping manifold is the responsibility of what component? 1. Transfer tank fill line shutoff valve 2. Transfer tank pressure buildup valve 3. Fill-drain line shutoff valve 4. Storage tank vent line shutoff valve 6-16. During filling operations on the TMU-70/M, the storage tank should not be allowed to rise above what pressure? 1. 25 psi 2. 38 psi 3. 55 psi 4. 73 psi 6-17. When the storage tank liquid level gauge indicates 50 gallons, what component should be closed? 1. Transfer tank shutoff valve 2. Transfer tank buildup valve 3. Transfer tank servicing valve 4. Supply tank servicing valve 6-18. Under normal conditions and 30 psi transfer pressure, the storage tank should fill within what time period? 1. 2 to 5 minutes 2. 2 to 10 minutes 3. 5 to 10 minutes 4. 5 to 15 minutes 6-19. Which of the following valves should be opened to allow the transfer tank to fill? 1. Transfer tank fill line shutoff valve 2. Fill-drain line shutoff valve 3. Converter vent line check valve 4. Converter vent line shutoff valve 6-20. As soon as the converter full indicator gauge reads LIQUID, which of the following valves should be closed? 1. Transfer tank fill line shutoff valve 2. Fill-drain line shutoff valve 3. Converter vent line check valve 4. Converter vent line shutoff valve 6-21. The transfer tank pressure buildup coil is used to increase the pressure in the transfer tank to what psi? 1. 70 psi 2. 90 psi 3. 110 psi 4. 123 psi 6-22. Maintenance information for the TMU-70/M is found in what publication? 1. A6-32AO-GYD-000 2. NAVAIR 19-25D-14 3. NAVAIR 19-25D-22 4. NAVAIR 19-25D-26 6-23. Which of the following fire agents is NOT prohibited for use on LOX-enriched fires? 1. Water 2. Soda-acid extinguishers 3. Mechanical (liquid) foam 4. Methyl bromide 6-24. Which of the following contamination tests is NOT required to be performed at a laboratory? 1. Sampling 2. Density 3. Volume 4. Odor 6-25. When performing a LOX odor test, how much of the LOX is needed? 1. 100 milliliters 2. 200 milliliters 3. 300 milliliters 4. 400 milliliters 6-26. When performing a LOX odor test, when will an odor be most prevalent? 1. As soon as the LOX is poured into a beaker 2. When the beaker has warmed to nearly room temperature 3. When the beaker has reached –20°F 4. When the LOX has set for 24 hours

24 6-27. Which of the following is the most dangerous contaminate of LOX? 1. Hydrocarbons 2. Water 3. Dust 4. Pollen 6-28. Which of the following is a method used in purging oxygen containers? 1. Oil-based nitrogen 2. Oil-based oxygen 3. LOX wash 4. LOX drying 6-29. The type No-2 cart contains how many oxygen cylinders? 1. Six 2. Eight 3. Three 4. Four 6-30. On the type No-2 cart, what valve is used to control the flow of oxygen from the cylinders to the system being serviced? 1. Cross control valve 2. Manifold control valve 3. Servicing control valve 4. Recharge valve 6-31. Which of the following components is NOT mounted on the upper manifold? 1. Recharge valve 2. Manifold control valve 3. Gauges 4. Drier assembly 6-32. How many shutoff valves does the type No-2 cart have? 1. One 2. Two 3. Three 4. Four 6-33. On the type No-2 cart, what component is used to remove moisture from the system? 1. Filter assembly 2. Drier assembly 3. Vent assembly 4. Moisture removal assembly 6-34. What amount of residual pressure should be kept in an oxygen cylinder? 1. 10 psi 2. 15 psi 3. 30 psi 4. 50 psi 6-35. When installing full cylinders on a type No-2 cart, which of the following is an ideal safety practice? 1. The cart should be connected to a towing vehicle 2. There should be a total of four personnel involved 3. Quality assurance personnel should be present 4. The installation should occur when the outside temperature is a maximum of 75°F 6-36. The two top cylinders on a type No-2 cart are attached by what means? 1. Cylinder wheel 2. Spot tie 3. Harness locks 4. Single strap 6-37. Interchanging of components with air/nitrogen equipment is authorized during what event, if any? 1. War time 2. Operational necessity 3. Parts ordered are not available from supply 4. Never 6-38. The chemical drying agent on the type No-2 cart should be inspected after how many cylinders are used? 1. 8 2. 12 3. 14 4. 16 6-39. What color will the chemical drying agent turn when moisture is present? 1. Pink 2. Blue 3. Green 4. Yellow

25 6-40. Which of the following components is NOT a major component on the A/U26U-1A oxygen servicing unit? 1. Trailer assembly 2. Gas storage system 3. Gas servicing system 4. Moisture removal assembly 6-41. The A/U26U-1A oxygen trailer contains how many wheels? 1. One 2. Two 3. Three 4. Four 6-42. The parking brake on the A/U26U-1A is operated by what means? 1. Hydraulic 2. Pneumatic 3. Electrical 4. Mechanical 6-43. The gas storage system on A/U26U-1A consists of how many oxygen bottles? 1. One 2. Two 3. Three 4. Four 6-44. The oxygen storage system on the A/U26U-1A is designed to operate at what maximum pressure? 1. 2000 psig 2. 2430 psig 3. 2640 psig 4. 2935 psig 6-45. The nitrogen storage system on the A/U26U-1A is designed to operate at what minimum pressure? 1. 125 psig 2. 175 psig 3. 200 psig 4. 225 psig 6-46. When compressed air is not available on the A/U26U-1A, what source, if any, can be used as an alternative? 1. Oxygen 2. Nitrogen 3. Helium 4. No other source is authorized 6-47. Compressed air used to drive the oxygen gas boost pump on the A/U26U-1A must be what percent moisture free? 1. 100 percent 2. 90 percent 3. 80 percent 4. 75 percent 6-48. The aviators oxygen used on the A/U26U-1A must conform to what military specification? 1. MIL-0-13270 2. MIL-0-27210 3. MIL-0-37420 4. MIL-0-48320 6-49. The gaseous nitrogen module on the A/U26U-1A supplies what minimum amount of unregulated compressed air? 1. 35 psig 2. 50 psig 3. 75 psig 4. 90 psig 6-50. The low pressure service adapter burst disc prevents the low pressure aircraft oxygen gas storage system from exceeding what pressure? 1. 600 psig 2. 800 psig 3. 1000 psig 4. 1200 psig