AVIATION MAINTENANCE RATINGS (AMR)

time-consuming, and reduce equipment usage time. These problems can be avoided through good preventive maintenance practices and procedures. To have good preventive maintenance practices and procedures, you must know and be able to apply the common types of corrosion prevention and moisture protecting materials. Q1. How does corrosion endanger aircraft or reduce the margin of safety? Q2. All maintenance personnel must be formally Q3. trained in what program? What is the primary factor to consider when selecting materials for constructing an aircraft? on unpainted areas of working parts. Finally, shrouds, covers, caps, and other mechanical equipment provide varying degrees of protection from corrosive mediums. However, none of these procedures will provide 100-percent protection. Weathering causes paint to oxidize and decay. Sealants may be worked out by vibration or be eroded by rain and windblast. Preservatives offer only temporary protection when used on operating aircraft. The mechanical coverings can be installed improperly or negligently. Control of corrosion begins with an understanding of the causes and the nature of corrosion. Corrosion is CORROSION THEORY in its most familiar form is a reaction between metal and water, and is electrochemical in nature. the process of electrochemical or direct chemical attack on metals. The reaction is similar to that which occurs when acid is applied to bare metal. Corrosion LEARNING OBJECTIVES: Define the theory of corrosion and its process. Identify the publications and materials used in the prevention of corrosion. Metal corrosion is the decay of metals as they combine with oxygen to form metallic oxides. Corrosion is a chemical process that is the reverse of the process of smelting the metals from their ores. Very few metals are found in their pure state in nature. Most are found as metallic oxides. These oxides have other undesirable impurities in them. The refining process involves the extraction of the base metal from the ore. The base metal is then mixed with other elements (either metallic or nonmetallic) to form alloys. Alloying elements are added to base metals to develop a variety of useful properties. For instance. in aircraft structural applications, high strength-to-weight ratios are the most desirable properties of an alloy. After the base metals are refined, whether alloyed or not, they have a potential to return to their natural state. However, potential is not sufficient in itself to begin and promote this reversion; a corrosive environment must also exist. The significant element of the corrosive environment is oxygen. The process of oxidation (combining with oxygen) causes wood to rot or bum and metals to corrode. Control of corrosion depends upon maintaining a separation between susceptible alloys and the corrosive environment. This separation is accomplished in various ways. A good intact coat of paint provides most of the corrosion protection on naval aircraft. Sealants used at seams and joints prevent entry of moisture into the metal. Preservatives are used The electrochemical attack involves metals of different electrical potential. These metals do not have to be in direct contact. If one metal contains positively charged ions and the other negatively charged ions, all that is needed is an electrical conductor. When the conductor is present, current will flow between the two metals, as in the discharge of a dry-cell battery. In electrochemical corrosion, the electrical conductor may be any foreign material, such as water, dirt, grease, or any debris that is capable of acting as an electrolyte. The presence of salt in any of the foregoing mediums accelerates the current flow and increases the rate of corrosive attack. Once an electrical connection is made, the electron flow is established in the direction of the negatively charged metal (cathode). This action eventually destroys the positively charged metal (anode). Preventive measures include avoiding the establishment of the electrical circuit and removing corrosion as soon as possible to avoid serious damage. Figure 4-1 shows the electron flow in a corrosive Figure 4-1.—Simplified corrosion cell. 4-2

environment destroying the anodic area. Note that the surface of a metal may contain anodic and cathodic areas because impurities or alloying constituents may have different potentials than the base metal. Electrochemical attack is evident in several forms. The form you find depends upon the metal involved, its size and shape, its specific functions, atmospheric conditions, and type of corrosion-producing agent (electrolyte) present. There are many factors that affect the type, speed, cause, and the seriousness of metal corrosion. Some of these factors you can control; others you cannot. Preventive maintenance factors, such as inspections, cleaning, painting, and preservation, are within the control of the operating squadron. They offer positive means of preventing corrosion. The electrochemical reaction, which causes metal to corrode, is more dangerous under wet, humid conditions than under dry conditions. The salt in seawater and the salt in the air are the largest single cause of aircraft corrosion. Hot climates speed the corrosion process because the electrochemical reaction develops fastest in a warm solution. The warm moisture in the air is usually enough to start corrosion of the metals if they are uncoated. As expected, hot, dry climates usually provide relief from constant corrosion problems. Extremely cold climates will produce corrosion problems when a salt-laden atmosphere is present. Melting snow or ice provides the necessary water to begin the electrochemical reaction. Thick structural sections are subject to corrosive attack because of possible variations in their composition, particularly if they were heat-treated during fabrication. Similarly, when large sections are machined or cut out after heat treatment, thinner sections have different physical characteristics than the thicker areas. Usually a difference in physical characteristics provides enough difference in electrical potential to make the piece highly susceptible to corrosion. Another factor relating to the size of materials is the relationship between dissimilar metals. (See figure 4-2.) If electrical contact develops between two dissimilar metals, the corrosion attack on the more active metal or anode (smaller size compared to the less active one) will be severe and extensive. See figure 4-2, bottom view. If the area of the less active metal is small compared to the other, anodic attack will be slight (fig. 4-2, top view). Corrosion on avionics equipment is a continuing process. The equipment does not have to be installed, operating, or exposed to a particularly harsh environment to corrode. The rate of the corrosion process is determined by the temperature, humidity, and chemicals in the environment. Moisture is the single largest contributor in avionics corrosion. It makes little difference whether the moisture is in the form of vapor or liquid. Its affects are detrimental to metals. A clean aircraft retains its aerodynamic efficiency and safety. Serious damage to the exterior and interior surfaces of aircraft can result from the lack of correct information about cleaning materials and equipment and their use. Shipboard procedures are not necessarily the same as procedures ashore, but the same materials are available to produce comparable results. A problem you may face when fighting corrosion is knowing what materials to use, where to find them, and their limitations. You should use only those materials that have military specifications. Corrosion control information can be found in many directives Figure 4-2.—Effects of area relationships in dissimilar metal contacts. 4-3

and instructions. This information is constantly revised to give you up-to-date knowledge and procedures. You can find the following sources of information on corrosion in your unit’s technical library or corrosion control work center. Aircraft Weapons System Cleaning and Corrosion Control for Organizational and Intermediate Maintenance Levels, NAVAIR 01-1 A-509 Avionics Cleaning and Corrosion Prevention/ Control, NAVAIR l6-l-540 Preservation of Naval Aircraft, NAVAIR 15-01-500 Chart-Corrosion Preventive Compounds used by Naval Air Systems Command, NAVAIR 01-l A-518 General use of Cements, Sealants, and Coatings, NAVAIR 01-1A-507 Ground Support Equipment Cleaning And Corrosion Control, NAVAIR 17-1-125 Corrosion Control, Cleaning, Painting, and Decontamination (One volume of the maintenance instruction manuals (MIMs) for all late model aircraft is devoted to these subjects.) Q4. Q5. Q6. Q7. Q8. Q9. Q10. Q11. Q12. Periodic Maintenance Requirements Cards The decay of metals as they combine with oxygen is known as what type of corrosion? What does an intact coat of paint provide to naval aircraft? In an electrochemical attack, electron flow is established in which direction? How will heat, humidity, and moisture affect the electrochemical reactions that cause metal to corrode? Why are thick structural sections most susceptible to corrosive attack? In relation to corrosion, what affect does moisture have on avionics equipment? Which NAVAIR publication is entitled Aircraft Weapons Systems Cleaning and Corrosion Control? NAVAIR 16-1-540 provides what information? Information on the preservation of Naval aircraft and aircraft engines can be found in what publication? Q13. What information can you find in NAVAIR 01-IA-507? PREVENTIVE MAINTENANCE LEARNING OBJECTIVE: Define the purpose of a preventive maintenance program. “An ounce of prevention is worth a pound of cure.” Where corrosion prevention on naval aircraft is concerned, this is an understatement. Compared to the cost of naval aircraft, the cost of corrosion prevention is small. Preventive maintenance is a powerful tool that can control even the most difficult corrosion problem. Most operating activities increase their corrosion prevention programs to meet severe conditions aboard ship. Then, these programs are decreased in scope when the aircraft is returned to the relatively mild conditions ashore. When corrosion preventive maintenance is neglected because of tactical operating requirements, a period of intensive care should follow to bring the aircraft back up to standard. The two most important factors in preventing corrosion, and the only factors that can be controlled by field personnel, are the removal of the electrolyte and the application of protective coatings. Since the extent of corrosion depends on the length of time electrolytes are in contact with metals, corrosion can be minimized by frequent washing. Prevention also involves the correct and timely use of covers and shrouds, periodic lubrication, and the application of preservatives. Years of experience have proven the need for such measures to keep the aircraft airworthy. When corrosion preventive maintenance is neglected, an aircraft soon becomes unsafe to fly. Squadrons with the best corrosion preventive programs tend to have the best safety records, maximum use of the aircraft, and the lowest operating costs. SUPPORT EQUIPMENT PREVENTIVE MAINTENANCE SCHEDULE The Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2, requires SE shops to establish a maintenance schedule for each item of equipment. The SE Custody and Maintenance History Record, OPNAV 4790/51, is used to schedule and record all corrosion maintenance actions. 4-4

SURFACE MAINTENANCE Surface maintenance includes regular cleaning of the aircraft as well as touch-up of protective paint coatings. Since paint touch-up is done after removal of corrosion, it is discussed later in this chapter. Touch-up of new damage to paint finishes prevents corrosion from starting. Aircraft must be washed and cleaned at least every 14 days, unless otherwise directed by NAVAIR. Aircraft must be kept in a clean condition, and repeated cleaning should be done as often as necessary. More frequent cleaning may be needed when the following conditions exist: An excessive amount of soil or exhaust gases accumulation within impingement areas Exposure to salt spray, salt water, or other corrosive materials Evidence of paint surface decay, such as softening, flaking, or peeling The presence of fluid leakage (excessive oil, coolant, hydraulic fluid, etc.) Immediate cleaning of affected areas is always mandatory if: Aircraft is exposed to corrosive fire- extinguishing materials Spilled electrolyte and corrosive deposits are found around battery terminals and battery area The aircraft has been exposed to significant amounts of salt water Salt deposits, relief tube waste, or other contaminants are apparent Fungus growth is apparent Chemical, biological, or radiological contaminants are detected A daily cleaning or wipe-down is required on all exposed, unpainted surfaces, such as struts and actuating cylinder rods. Aircraft must be thoroughly cleaned before they are stored. They should also be thoroughly cleaned when they are depreserved. Unpainted aircraft are cleaned and polished at frequent intervals. Aboard ship, cleaning and removal of salt deposits are needed to prevent possible corrosion. Components that are critically loaded (designed with minimum safety margins to conserve size and weight) are cleaned as often as possible to minimize exposure to corrosive agents. These components include helicopter rotor parts and parts that are exposed to corrosive environments (such as engine exhaust gas, acid, or rocket blast). NOTE: Postcleaning lubrication and preservation of exposed components are necessary to displace any of the cleaning solution entrapped during the cleaning operation. Q14. Q15. Q16. Q17. Q18. What should happen to a good corrosion preventive program when carrier-based aircraft return to a shore activity after a deployment? Operating units that have the best safety records, maximum use of aircraft, and lowest operating costs will also have what program? At a minimum, how often must aircraft be cleaned? List the conditions that require the affected areas of an aircraft to be cleaned immediately. What must be done on a daily basis with unpainted aircraft surfaces and actuating rods? AVIONICS MAINTENANCE A successful avionics cleaning and corrosion prevention and control program depends upon a successful preventive maintenance program. The nature of corrosion requires that everyone involved in the repair and operation of electrical, electromechanical, and electronic systems be concerned with the corrosion control of avionic equipment. You should recognize the difference between the prevention of corrosion and the repair of damage caused by corrosion. Preventive maintenance programs at organizational- and intermediate-level maintenance activities accomplish the following: Reduce the maintenance time spent repairing corrosion damage Ensure the military avionics community is aware of the extent of the corrosion problem Improve avionics system reliability, durability, and service life Report any and every deficiency with material or process involving corrosion control CLEANING MATERIALS LEARNING OBJECTIVE: Identify the hazards of handling and storing aircraft cleaning materials. 4-5

When cleaning or performing corrosion control on aircraft and nonavionics aircraft components, you should use the materials listed in Aircraft Cleaning and Corrosion Control for Organizational and Intermediate Maintenance Levels, NAVAIR 01-1A-509. You may use materials that do not conflict with the 509, as listed in the MIM and maintenance requirements cards (MRCs) that apply. For avionics and electrical systems, you should refer to the Avionic Cleaning and Corrosion Prevention/Control, NAVAIR 16-l-540. Cleaning agents commonly used by O- and I-level maintenance activities are described in the following text Figure 4-3.—DoD Hazardous Chemical Warning Label. CAUTION You must read the Material Safety Data Sheet (MSDS) before you use any hazardous mate- rial. Hazardous Materials Hazardous material is any material presenting hazards to personnel, property? or the environment by handling, storing, and using such materials. Hazardous materials can be used safely if you take extra precautions when handling and storing these materials. Hazardous material, such as chemicals, require a hazardous chemical or material identification label. Figure 4-3 shows a DoD Hazardous Chemical Warning Label. DoD personnel must use this label on DoD manufactured hazardous materials, repackaged containers, tanks of hazardous chemicals, and unlabeled materials already in the DoD system. Manufacturers use various symbols and DOT shipping labels with the required Occupational Health and Safety Administration (OSHA) labeling. Used alone, these DOT symbols or labels do not meet the OSHA labeling requirements. Navy personnel should not place any labels on containers that already have proper labels. If you buy or receive a hazardous material with the minimum required labeling, do not add any additional labeling. If you have an unlabeled container or one with a damaged label, you can print a label from the HMIS CD-ROM or use DD Form 2522. Flammable and Combustible Liquids Combustible liquids are any liquids that have a flash point at or above 100°F, but below 200°F. Flammable liquids are any liquids that have a flash point below 100°F. Fire is a very serious hazard. An equal hazard to personnel is breathing poisonous (toxic) fumes in unventilated spaces. NOTE: Flash point is defined as the minimum temperature at which a liquid gives off an ignitable vapor within a test vessel. Solvents Solvents are liquids that dissolve other substances. They are used in many products, such as paints, degreasing fluids, and aircraft cleaning compounds (an organic solvent). Aside from posing a fire hazard, inhaling the vapors can seriously affect the brain and 4-6

the central nervous system. Therefore, you should use solvents only in well-ventilated spaces. You should wear gloves, an apron, and a face shield to protect your skin and eyes. You should also don an approved respirator to prevent breathing of the toxic vapors. Without protection, skin lesions, much like acne, may develop. If you do not use rubber gloves, your hands will lose their fatty protection and the skin will dry, crack, and become infected. Some solvents are chlorinated. When solvents contain more than 24 percent by volume of chlorinated materials, they must be kept in specially marked containers. You must ensure the equipment in which the solvent is used is designed and operated to prevent escape of the solvent. All personnel who work near chlorinated solvents should be careful to avoid breathing the vapors. While the vapors from some solvents are more toxic than others, prolonged breathing of any fumes presents a serious health hazard. Keep all containers holding paints, lacquers, removers, thinners, cleaners, or any volatile or flammable liquids tightly closed when not in use. Store all flammable and volatile liquids in a separate building or a flammable liquids storeroom. The approved flammable storage locker should be well ventilated. It should be located where its contents will not be exposed to excessive heat, sparks, flame, or direct rays of the sun. Storage areas must also have a fixed CO 2 or Halon extinguishing system. All electrical fixtures, outlets, and other wiring must be of the explosionproof class. Place wiping rags and other flammable waste material in tightly closed containers. You must empty these containers at the end of the work shift. You should keep in mind that the temperature inside the paint locker could become very high, especially during the summer months. As the temperature increases, liquids expand. Maintenance personnel have received serious chemical bums on the face, hands, and arms from opening a hot can of solvent. This hazard increases many times when personnel work with the more volatile liquids, such as paint strippers. Before opening a container of solvent that has been stored in a high-temperature area, you should cool it down. You can do this by using a stream of water. Use common sense around flammable and volatile liquids. When storing containers, you must handle them carefully to avoid breakage and spillage. If you stack the containers, the lower containers may be overloaded, causing leaks to develop along seams. This results in a loss of material. To prevent an accumulation of water and debris in their upper ends, store the containers on their sides or cover them with a tarpaulin. Before you store containers, you should inspect them for leaks and ensure complete closure of all plugs, caps, and covers. Inspect stored containers frequently for leakage, rust, or any other condition that may cause a problem. Correct deficiencies immediately. When storing materials outdoors, you should protect the containers from the weather with tarpaulins or sheds. This reduces the likelihood of water contamination. When you use tarpaulins, lash them in place securely and position them so that air is free to circulate around the containers. Another hazard associated with solvents (and to a certain extent with all cleaning materials) is their effect on the material being cleaned. Some solvents, such as methyl ethyl ketone and toluene, will damage rubber, synthetic rubber, and asphalt coverings. You should always consider this damaging effect when selecting cleaning materials. Most cleaning materials may do a good job in removing dirt, grease, oil, and exhaust gas deposits. However, they may also soften and ruin an otherwise good paint coating. For specific information on solvents, you should check NAVAIR 01-l A-509. Some solvents, consumable materials and their characteristics are described in the following text. Solvent, Dry-cleaning. This material is a petroleum distillate commonly used in aircraft cleaning. It is a general all-purpose cleaner available in three types and is used for metals, painted surfaces, and fabrics. It is applied by spraying, brushing, dipping, or wiping. Aliphatic Naphtha. Aliphatic naphtha is an aliphatic hydrocarbon product used as an alternate compound for cleaning acrylics. You may also use it for general cleaning purposes when you want fast evaporation and no film residue. Apply by dipping and wiping. DO NOT rub saturated surfaces vigorously. DO NOT use aliphatic naphtha with a synthetic wiping cloth, because it is a highly volatile and flammable solvent. Because it has a flash point below 80°F, use only in well-ventilated areas. Safety Solvent. Methyl chloroform is for use where a high flash point is required. Use it for general cleaning and grease removal from assembled and disassembled engine components in addition to spot 4-7

cleaning. Do not use it on painted surfaces. Safety solvent is not suitable for oxygen systems. It can be used for other cleaning in ultrasonic cleaning devices. Apply it by wiping, scrubbing, or booth spraying. The term safety solvent is derived from its high flash point. Many later-issue maintenance manuals refer to safety solvent as 1,1,1-trichloroethane. Methyl Ethyl Ketone (MEK). Methyl ethyl ketone (MEK) is a cleaner for bare-metal surfaces and areas where MIL-S-8802 sealant is to be removed. Normally, you apply MEK over small areas with wiping cloths or soft bristle brushes. CAUTION Avoid prolonged breathing and skin con- tact of MEK. Use MEK only in well-venti- lated spaces. Use extreme care when working around transparent plastics because MEK will damage them upon contact. Trichloroethane. This is a nonflammable degreasing agent for cleaning oxygen systems equipment. It can be harmful to paint and plastic materials and since its vapors are heavier than air, it will displace oxygen in poorly ventilated areas. Ammonium Hydroxide. Normally, you use ammonium hydroxide in the lavatories of aircraft to neutralize urine and waste products. Use a sponge to apply it, and then flush the area with fresh water. Sodium Bicarbonate. Sodium bicarbonate also neutralizes urine deposits. You apply it with a sponge, and then flush the area with fresh water. Sodium bicarbonate is also a neutralizing agent for sulfuric acid battery electrolyte deposits. Sodium Phosphate. Sodium phosphate neutralizes electrolyte spills from nickel-cadmium batteries. Remove spilled electrolyte immediately by flushing with fresh water. Neutralize the area by sponging generously with sodium phosphate solution and then flush with fresh water. Dry with clean wiping cloths. Aqueous Film-forming Foam. Aqueous film-forming foam is commonly known as AFFF. Use it for removing fire-extinguishing agent MIL-F-24385 from aircraft surfaces. Complete details for the use of AFFF as a cleaning agent are in Aircraft Weapons System Cleaning and Corrosion Control. NAVAIR 01-1A-509. Aircraft Surface Cleaning Compound Maintenance personnel use water emulsion cleaners to clean aircraft. These cleaners disperse contaminates into tiny droplets that are held in suspension. The droplets of this cleaner are then flushed from the surface. MIL-C-43616 water emulsion compounds contain emulsifying agents, coupling agents, detergents, solvents, corrosion inhibitors, and water. Use these compounds on painted and unpainted surfaces in heavy-duty cleaning operations, when materials of lower detergency are not effective. Use these compounds in varying concentrations, depending upon the condition of the surface. Apply water emulsion cleaner by starting at the bottom of the area being cleaned. You may apply the mixed solution by spraying or brushing to avoid streaking. Loosen surface soils by mild brushing or mopping. Then, give the surface a thorough fresh water rinse by using an automatic shutoff-type water spray nozzle. This type of nozzle gives hand control from a light mist or fogging spray to a full spray with high-pressure water. Aircraft cleaning compound MIL-C-85570 is the primary cleaning compound used on naval aircraft. The five types of MIL-C-85570 are discussed in the following text. TYPE I is for cleaning painted and unpainted aircraft outdoors or where enough ventilation is available. It may be used to clean either high-gloss or tactical paint systems. TYPE II is for cleaning painted and unpainted aircraft indoors and in areas of limited ventilation. It is for cleaning either high-gloss or tactical paint systems. Type II is not as good as type I for these purposes. It may also be used outdoors. TYPE III is a mild abrasive cleaner. It is used undiluted for spot cleaning high-gloss paint systems, such as exhaust tracks, shoe scuff marks, and other areas where types I and II are not effective. TYPE IV is a spot cleaner for Tactical Paint Scheme (TPS). For spot cleaning embedded soils on TPS systems without changing the paint finish. TYPE V is for cleaning heavy soils, such as carbonized oil, aged preservatives, grease, and gun blast and exhaust deposits. This cleaner clings to 4-8

vertical oily or greasy surfaces where water rinsing can be tolerated. AVIONIC CLEANING MATERIALS The materials discussed in this section are the ones used most often when avionics and electrical equipment are cleaned. For a complete list, description, and application of avionic cleaning materials. you should refer to NAVAIR 16-l-540. MIL-D-16791, type 1 detergent, is used to clean transparent plastics and glass. Also, it is used at I-level maintenance activities as a water-based solvent spray in cleaning booths and aqueous ultrasonic cleaners. For cleaning by hand, you should apply it to the area to be cleaned with a flannel cloth, let it dry, and then remove it with a flannel cloth. Trichlorotrifluoroethane is commonly known as Freon (MIL-C-81302 cleaning compound). It is a general cleaner for avionic and electrical systems. You can use MIL-C-81302 Freon as type I (ultraclean) or type II cleaner. The uses for these types of cleaners are discussed in the following text. TYPE I, MIL-C-81302, is used on precision equipment where an ultraclean solvent is required. It is used in clean room applications in intermediate-level maintenance activities. TYPE II: MIL-C-81302, is used on all internal areas of avionics equipment. Normally, type II should be filtered before it is used. It can be used to clean dirt and dust from areas before soldering. The application procedures and restrictions applying to MIL-C-81302, types I and II, are the same. They are as follows: Apply by wiping or scrubbing the affected area with an acid brush or toothbrush. Air dry or oven dry, as applicable. Do not use on acrylic plastics or acrylic conformal coatings. Do not use on unsealed aluminum electrolytic capacitors. Damage may result to end caps and cause leakage. Isopropyl alcohol (TT-I-735) is a general-purpose cleaner and solvent. Use it to remove salt residue and contaminants from internal avionics and electrical equipment. Use an acid brush or pipe cleaner to apply a solution of isopropyl alcohol and water. Then, wipe clean and air dry. NOTE: Isopropyl alcohol is highly flammable and requires the same handling and storage procedures as other solvents. MECHANICAL CLEANING MATERIALS Mechanical cleaning materials consist of items such as abrasive papers: polishing compounds, polishing cloths, steel wool, and wadding. These materials are available in the supply system. However, use them as outlined in the cleaning procedures section of NAVAIR 01-1A-509 and the specific MIM. These procedures prevent damage to finishes and surfaces. In cases of conflicting information, NAVAIR 01-1A-509 always takes precedence. Aluminum oxide abrasive cloth is available in several forms. It is safe to use on most surfaces because it does not contain sharp or needlelike abrasives. Avoid the use of silicon carbide papers as a substitute for aluminum oxide. The grain structure of silicon carbide is sharp. It is so hard that individual grains can penetrate steel surfaces. Impregnated cotton wadding is used to remove exhaust gas stains and to polish corroded aluminum surfaces. It is also used on other metal surfaces to produce a high reflection. Aluminum metal polish is used to produce a high-luster, long-lasting polish on unpainted aluminum-clad surfaces. It is not used on anodized surfaces because it will remove the oxide coat. Q19. Q20. Q21. Q22. Q23. Q24. Q25. What are the most serious hazards in handling, using, and storing aircraft cleaning materials? Why is there a requirement to use a respirator when working with solvents? What must be done specifically when storing solvents that contain more than 24% chlorinated materials? Where must flammable liquids be stored when not in use? By what means is dry-cleaning solvent applied? Safety solvent is currently referred to by what name? List the application procedures and restrictions that apply to ML-C-81302, types I and II. 4-9

Q26. What material must be avoided as a substitute to aluminum oxide abrasive cloth and why? CLEANING EQUIPMENT LEARNING OBJECTIVE: Identify the cleaning compounds used in aircraft cleaning and the procedures for washing aircraft. Cleaning aircraft surfaces requires the correct cleaning materials and the use of properly maintained equipment. The choice of equipment depends upon several factors. Some of these are the amount of cleaning regularly performed, the type of aircraft, location of the activity, and the availability of air pressure, water, and electricity. Several types of specialized equipment are available for cleaning aircraft. These include pressure-type tank sprayers, a variety of spray guns and nozzles, high-pressure cleaning machines. and industrial-type vacuum cleaners. One piece of specialized equipment, the automatic water spray nozzle, is shown in figure 4-4. A device used for the fast, economical cleaning of aircraft is a swivel-type, conformable applicator cleaning kit (fig. 4-5). Its design allows you to clean aircraft exteriors faster than with cotton mops or bristle brushes. Its official designation is the Aircraft Cleaning Kit No. 251. The swivel and applicator head is attached to a standard brush handle. Because it conforms to the surface, the applicator allows easier application of a constant scrubbing pressure on curved skin panels. It does this by keeping the brushes in maximum contact with the surface. When you use these brushes, you must make sure they do not cause a FOD problem. CLASSIFICATION AND REMOVAL OF SOILS Soils may be classified and removed as described below: Lightly soiled surfaces (dirt, dust, mud, salt, and soot). Use the proper mixture of MIL-C-85570 and fresh water. Moderately soiled surfaces (hydraulic oils, lubricating oils, and light preservatives). Use a proper mixture of MIL-C-85570 and fresh water. Heavily soiled surfaces (carbonized oils, aged preservatives, grease, gun blast deposits, and exhaust Figure 4-4.—Automatic water spray nozzle. 4-10

Figure 4-5.—Aircraft washing applicator. trails). Pretreat with P-D-680, followed by cleaning with the proper mixture of MIL-C-85570 and fresh water or MIL-C-43616. Soiled surfaces on the tactical paint scheme (low visibility flat paint scheme). Use MIL-C-85570, types I, II, or IV for cleaning tactical paint systems according to mixture directions. CLEANING PREPARATION The first step in cleaning an aircraft is to select the proper cleaning agent for the method of cleaning you will use. Next, the aircraft must be prepared for cleaning. Ground the aircraft to the deck. Static electricity generated by the cleaning operation will be dissipated through the ground wire. If the aircraft surface is hot, cool it with fresh water before starting any cleaning operation. Many cleaning materials will clean faster at elevated temperatures. However, the risk of damage to paint, rubber, and plastic surfaces is increased. This damage is caused by the cleaners, which are concentrated by the solvent evaporating quicker at high temperatures. Secure openings, such as canopies, doors, and access panels. Some equipment and components, such as air-sensing probes (pitot tubes), can be damaged by moisture and cleaning agents. To prevent the entrance of moisture, cover these and similar openings with either the proper aircraft cover or with masking tape, as specified in NAVAIR 01-1A-509, Appendix A. CLEANING METHODS There are several different methods for cleaning naval aircraft. These methods vary, depending upon the availability of fresh water. Water-Detergent Cleaning The water-detergent cleaning method is the preferred method for cleaning naval aircraft. Use this method when enough fresh water is available for rinsing. After preparation, wet down the aircraft surface to be cleaned with fresh water. Then, apply a concentrated solution of cleaning compound and water to heavily soiled areas. Scrub these areas and allow the concentrated solution to remain on the surface. Limit the size of the area you are cleaning to an area that can be cleaned while it is still wet. Next, apply a diluted solution of cleaning compound and water. The solution should be in a ratio suitable for the type of soil present in accordance with NAVAIR 01-1A-509. Apply this solution to the entire surface to be cleaned (upward and outward), including those areas previously covered with concentrated solution. The proper washing procedure is shown and described in figure 4-6. Scrub the surfaces thoroughly, and allow the solution to remain on the surface for 5 to 10 minutes before rinsing. Rinse the lower surfaces and work upward. Then rinse from the top down, starting with the vertical stabilizer, upper fuselage, upper wing surfaces, and horizontal stabilizers. Rinse lower areas in the same order and manner as the upper surfaces. If a high-pressure stream of water is used for rinsing, hold the nozzle at an angle and at a reasonable distance from the surface being sprayed. If any areas are still not clean, repeat the operation in those areas only. Thorough rinsing minimizes streaking. 4-11

Figure 4-6.—Aircraft washing procedures. 4-12

Detergent Cleaning With Limited Water Use this method only when water is limited. Prepare the aircraft for cleaning. Then mix the proper amounts of aircraft cleaning compound and water in a bucket. Apply the cleaner with a scrub brush, sponge, rag, or cleaning and polishing pad. Apply to one small area at a time. Scrub the area. Then remove the cleaner and loosened soils with a cloth. For soils that are resistant to the limited water procedure, clean with dry cleaning solvent (P-D-680, Type II or III) then repeat with the cleaning compound and water mixture. Apply water displacing, ultrathin, film corrosion preventive compound MIL-C-81309, type II, and wipe with a clean, dry cloth. Waterless Wipedown Cleaning Use waterless wipedown procedures only when water is not available for rinsing or when cold weather prevents the use of water. Using a plastic spray bottle, apply MIL-C-85570, Type I or II (mixed IAW NAVAIR 01-1A-509). Alternatively, spray the cleaner from an aerosol can and wipe off contaminates from the surface. Spot Cleaning Spot clean light, oily, soiled surfaces by wiping with dry-cleaning solvent. Apply the solvent by using a saturated wiping cloth. Brush or wipe the surface as necessary; then wipe clean with a dry cloth. The solvent wipe may leave a light residue. Remove this residue with soap and water, followed by a fresh water rinse. NOTE: After cleaning an aircraft, relubricate it as specified by the MRCs. Ensure that all low-point drains are open, covers and shrouds are removed, and that aircraft preservatives are applied to clean, exposed, unpainted surfaces. Also make sure that the felt wiper washers on all hydraulic cylinders are moistened, and wipe down actuating cylinder rods with a clean rag saturated with hydraulic fluid. Remove and replace damaged or loosened sealant as specified by the applicable MIM. Q27. Why is the conformable applicator cleaning pad better than a mop or bristle brush when cleaning aircraft surfaces? Q28. Types I, II, and IV of what cleaning compound are to be used on tactical paint schemes? Q29. What is the first step in efficiently cleaning an aircraft? Q30. When cleaning an aircraft what are the two directions in which cleaning compound and rinsing are applied? Q31. What substance may be used to spot-clean lightly soiled areas? AVIONICS EQUIPMENT CLEANING Dust and contamination cause corrosion problems in avionics equipment. Cleaning prevents many of these problems. Therefore, cleaning is the first logical step after an inspection. Cleanliness is very important in maintaining the functional integrity and reliability of avionic systems. Dirt may be either conductive or insulating. As a conductor, it may provide an undesired electrical path. As an insulator, it may interfere with proper operation. Dust, fingerprints, surface oxides, contaminants, or other foreign material on a surface can undo all the good provided by protective coatings. A good maintenance practice is to use the mildest cleaning method that will properly decontaminate the equipment. It is also important to use the correct cleaning solutions and cleaning materials to avoid damage to avionics equipment. Some of the hazards associated with the cleaning of electronic and electrical equipment are as follows: Cleaning solvents or materials can be trapped in crevices or seams. This interferes with later applications of preservative coatings and causes corrosion as well. Vigorous or prolonged scrubbing of laminated circuit boards can damage the boards. Certain cleaning solvents soften conformal coatings, wire coverings, acrylic panels, and some circuit components. WARNING Dry-cleaning solvent should not be used in oxygen areas or around oxygen equipment. Dry- cleaning solvent is NOT oxygen compatible and will cause explosion and/or fire. 4-13

When dust. contaminants, or corrosion are detected, action is required. If the corrosion is within repairable limits specified in the applicable MIM or local directive. initiate corrective action. Corrective action includes cleaning, corrosion removal, treatment. and preservation. The nature of some surfaces, such as chrome-, nickel-, gold-, and silver-plated contacts. limits the use of highly abrasive cleaning methods. You can remove tarnish and light corrosion from these surfaces by rubbing with one of the following materials: An eraser (conforming to specification ZZ-E-661) known as magic rub, ruby red, wood, or paper encased (pencil-type) or typewriter eraser A nonabrasive cleaning pad (MIL-C-83957) for laminated circuit boards. waveguides, relay contacts. etc. A brush (toothbrush H-T-560 or typewriter brush H-B-681) for general scrubbing of dirt, soil, and corrosive products on circuit components Remove light to heavy corrosion from surfaces, such as covers, connectors, receptacles, antenna mounts, equipment racks, and chassis, by hand rubbing and by using aluminum oxide abrasive cloth. You may use either MIL-A-9962, type I, grade A (very fine), grade B (fine), or aluminum oxide abrasive cloth P-C-451, 320 grit, to do this task. USE OF COVERS AND SHROUDS When an aircraft is delivered by the manufacturer, it has a complete set of tailored dust and protective covers. Figure 4-7 shows a typical set of covers. Install all covers so free drainage will occur. Do NOT create a bathtub that will trap-and hold water. In warm weather, shrouds and covers cause a greenhouse effect, and cause condensation of moisture. Therefore, loosen and remove shrouds and covers and ventilate the aircraft on warm sunny days. However, where protection from salt spray is required, leave the covers in place, and ventilate the aircraft in good weather Figure 4-7.—Dust and protective covers. 4-14

only. Fresh water condensation does far less damage than entrapped salt spray. In emergencies where regular waterproof canvas covers are not available, use a polyethylene sheet, polyethylene-coated cloth, or metal foil barrier materials as covers and shrouds. Hold these covers in place with adhesive tape that is designed specifically for severe outdoor applications. GROUND HANDLING REQUIREMENTS The MIM for an aircraft usually describe brief and simple ground-handling procedures. When followed, these procedures reduce corrosive attack. These procedures keep water, salt, and dirt out of areas that are difficult to get at and easy to overlook. As you can see, they also save a tremendous amount of maintenance work later. Many practices, when followed, lessen paint damage and the loss of built-in protective systems during normal ground handling of the aircraft. Some of these practices are listed below. Use the tie-down points provided. Much damage is done to aircraft paint films by failure to use the tie-down points or by passing tie-down cables and lines over or around supporting structures so the paint finish is worn, chipped, or broken. Take time to wipe or brush sand or gravel from shoe soles before climbing on the aircraft. Painted aircraft surfaces will withstand a normal amount of foot traffic and abrasion by fuel hoses and air lines. However, shoe soles and fuel hoses pick up bits of sand, gravel, and metal chips. These become a coarse abrasive that scratches and scuffs the protective finish so it is completely ineffective under shipboard operating conditions. Do not place removed hardware on the deck. When you remove cowling and access plates during inspections and you cannot provide pads or cushions for them, secure them to prevent their movement. Avoid scratching the paint when you use hand tools to remove screws and quick-opening fasteners on aircraft exteriors. As little as 5 minutes of extra time spent carefully using tools might save hours of paint touch-up and corrosion removal. Q32. Why should dry-cleaning solvent not be used in oxygen areas or around oxygen equipment? Q33. In emergencies when regular waterproof canvas covers are not available, what materials can you use as covers and shrouds? Q34. The ground handling requirements for an aircraft can be found in what publication? RECOVERY AND RECLAMATION OF CRASH DAMAGED AIRCRAFT LEARNING OBJECTIVE: Identify publications used to describe emergency reclamation procedures. General procedures are required anytime an aircraft is exposed to gross amounts of saltwater or fire-extinguishing agents. Each activity that is assigned custody of aircraft has a recovery and reclamation team. The size and composition of the team depend upon the urgency of the situation. As a maintenance crew member, you may be called upon to assist with reclamation of an aircraft. Recovery and reclamation procedures are covered in detail in NAVAIR 01-1A-509. Methods for cleaning support equipment (SE) are different from those used to clean aircraft. Authorized SE cleaning materials and procedures are identified in Ground Support Equipment Cleaning and Corrosion Control, NAVAIR 17-1-125. Q35. What technical publication covers emergency reclamation procedures for naval aircraft? LEVELS OF AIRCRAFT PRESERVATION LEARNING OBJECTIVES: Describe the levels of aircraft and engine preservation. Identify the preservatives and sealants used in the preservation of aircraft and support equipment. The exposure of an aircraft to corrosion damage is greatest when the aircraft is dirty, inactive, or being shipped. Aircraft spend more time on the ground than in the air, even in an active squadron. Therefore, they must be effectively protected. The method of preservation is based on complexity of the aircraft. A variety of methods are used to preserve aircraft. Preservation applies to all types of naval aircraft. There are three different levels of preservation used on naval aircraft: 4-15

Level Use I Short-term preservation of flyable and nonflyable aircraft for periods up to 60 days Preservation of aircraft for shipment and forII periods of 60 days to 1 year Preservation for long-term aircraft storageIII for periods of 1 to 8 years NOTE: Level I preservation will have special MRCs for each aircraft/engine. As a maintenance crew member, you will be involved with level I preservation. Anytime an aircraft is out of service or will remain idle for 14 or more days, maintenance will put the aircraft in level I preservation. You will use special MRCs to preserve, maintain preservation, and depreserve an aircraft. Protection against corrosive attack on aircraft is achieved by placing a barrier between the surface and any possible source of moisture. During overhaul or manufacture, protective barriers, such as electroplate, paint, or chemical surface treatment, are provided. Surfaces that cannot be so treated (in some instances, the treated surfaces themselves) are covered with special corrosion-preventive compounds. These compounds are effective only if no moisture, dirt, or active corrosion is present on the treated surface. Therefore, you must thoroughly clean and dry the aircraft before applying a preservative compound. Also, you must apply an unbroken film of preservative in as moisture-free an atmosphere as possible. Complete protection is not provided by compounds alone. Tapes, barrier paper, and sealing devices are used to seal off the many openings on aircraft. If these openings were to remain open during long-term storage, moisture and dirt would enter and accumulate. To provide additional protection against corrosion, a complete moisture barrier is sometimes used on aircraft. Unless the cavity is protected by a vapor corrosion inhibitor, use desiccants to dehydrate internal areas that have been sealed. When an area cannot be sealed adequately, provide ventilation and moisture drainage. When installed equipment in an aircraft is not being regularly used, its components must be preserved. For example, the guns of an aircraft must be cleaned after each firing. The type of oil or other protective treatment used depends upon the anticipated period of idleness for the guns. In the maintenance of aircraft surfaces under operating conditions, preservation adds to the protection already present. Also, protection coating and barrier materials provide temporary protection to damaged areas. A brief description of some of the more common materials used in aircraft preservation that are readily available in Navy stock is given in the following text. Corrosion-Preventive Compound, Solvent Cutback Corrosion-preventive compound, solvent cutback, comes in grades for specific applications. There are five grades of this compound, three of which are commonly used and do not displace water, grades 1, 2, and 4. All grades can be removed with dry-cleaning solvent. These materials are designed for cold application. 4-16 Grade 1 preservative forms a dark, hard-film, opaque cover. Its general use is limited because of the difficulty in removing aged coatings. Also, it hides what corrosion is present when it is applied over corroded areas. This material is used where maximum protection against salt spray is required. The military specification is MIL-C-16173, grade 1. Grade 2 is a thick soft, greaselike compound which is used primarily to protect metal surfaces against corrosion during rework or storage periods. The military specification is MIL-C-16173, grade 2. Grade 4 preservative forms a thin, semitransparent film through which identification dates can be read. It sets up dry enough to the touch, so preserved parts may be handled easily. This grade is effective in protecting wheel well areas and other exposed surfaces where film transparency is required and moderate protective characteristics can be tolerated. Its main disadvantage is that it is easily removed by water spray and requires replacement at l-month intervals under severe exposure conditions. The military specification is MIL-C-16173, grade 4. Coating Compounds Activities based outside the Continental United States sometimes receive aircraft via ocean surface shipment. This is especially true of helicopter and limited-range fighter aircraft. These aircraft are

protected during shipment with a sprayable, strippable coating system that conforms to MIL-C-6799, type II. Normally, type II coatings are safe on metal, plastic, or painted surfaces. Also, they are useful for protecting clear acrylic surfaces, such as canopies, against abrasion during maintenance or extended periods of downtime. The type II system consists of a black base coat and a white topcoat that provides heat reflection during outside exposure. Nylon ripcords with finger-size loops are placed about the aircraft before the aircraft is sprayed with this coating. This allows manual stripping of coatings. When properly applied, the coatings can be removed easily. If coatings are sprayed too thin for easy removal, they can be recoated and allowed to dry. The top layer will bond to previous layers, and all layers may be manually stripped in one operation. Corrosion-Preventive Petroleum (MIL-C-11796) MIL-C-11796 is designed for hot application. It is available in two classes, class 1 (hard film) and class 3 (soft film). Both classes consist of corrosion inhibitors in petroleum. They are removed with Stoddard solvent or mineral spirits. Where a hard film is not necessary, you should use class 3. Class 3 is easier to apply and remove, yet it gives the same degree of protection as class 1. Class 1 is for long-time, indoor protection of highly finished metal surfaces and aircraft control cables. Class 3 provides protection for metal surfaces, such as antifriction bearings, shock-strut pistons, and other bright metal surfaces. Class 1 must be heated to 170°F to 200°F before it is applied by brush or dip. For brushing, class 3 material must be between 60°F and 120°F, and for dipping, between 150°F and 180°F. Oil, Preservative, Hydraulic Equipment (MIL-H-46170) Use hydraulic fluid MIL-H-46170 as a preservative fluid to store hydraulic systems and components. It is also used as a testing medium in stationary test stands within a temperature range of -40°F to +275°F. Hydraulic fluid MIL-H-46170 is NOT to be used in portable test stands that are connected to the aircraft. This hydraulic fluid is a fire-resistant, synthetic, hydrocarbon, hydraulic fluid similar to MIL-H-83282. MIL-H-46170 is used as a preservative fluid in systems operating on MIL-H-83282. Lubrication Oil, General-Purpose, Preservative There are several types of lubricating oils, some of which contain preservatives. Each oil is identified by a specification number. Use the correct oil for each situation. The specification number for the oil described in this section is VV-L-800. VV-L-800 oil is used to lubricate and protect piano-wire hinges and other critical surfaces. It is also used when a water-displacing, low-temperature, lubricating oil is required. You may apply VV-L-800 as received by brush, spray, or dip. It is readily removed with dry-cleaning solvent or mineral spirits. Corrosion-Preventive Compound (MIL-C-81309) MIL-C-81309 corrosion-preventive compound is a water-displacing compound and lubricant that must be reapplied frequently. On exposed surfaces, protection lasts about 7 days at best. On internal areas, protection lasts about 30 days. MIL-C-81309 is available in two types—type II and type III. Type II is used for external areas. It forms an effective barrier against moisture when used on B-nuts, linkages, bolts, nuts, ejection seat mechanisms, and canopy locks. When you lubricate an area where there are no pressure lubricating fittings (zerk fittings), such as the piano hinges on access doors and control surfaces, spray with type II preservative compound to clean the area before you apply VV-L-800 preservative oil to remove moisture and contaminants. Type III corrosion-preventive compound is for avionics and electrical equipment usage. It is not for use on exterior areas that will be exposed to the environment. Type III is used primarily on electrical connectors (cannon plugs) and microswitches to remove moisture and contaminants and to prevent corrosion. Packaging and Barrier Materials A minimum of packaging is necessary at the operating activity level. However, critical aircraft and engine areas require shrouding against contamination during maintenance and repair. The fuselage must be sealed when cleaning and stripping materials are used 4-17

on the aircraft. There are several barrier materials available in the Navy stock for sealing and shrouding large aircraft openings. The stock numbers for these materials can be found in NAVAIR 01-1A-509. Water-vaporproof Barrier Material. This material is a laminated metal foil barrier that has good water-vapor resistance. It is used for closing intake openings, protecting acrylics during cleaning, and for the packaging of removed components and accessories that are returned for overhaul. It is heat sealable with a soldering or clothes iron. Polyethylene Plastic Film. This barrier material is used for the same purpose as the metal foil barrier material, but it is less expensive. However, it is not puncture resistant. This plastic film is heat sealable only with special equipment. Polyethylene Coating Cloth. This cloth is used in support equipment covers. Its use is preferred over plastic film material for general shrouding because of its greater tear and puncture resistance. Tape, Federal Specification PPPT-60, Class 1. This pressure-sensitive tape is used to close small aircraft openings and for direct contact use on noncritical metallic surfaces. It has moderate water-vapor resistance that is adequate for maintenance use. Pressure-sensitive Adhesive Tape. This tape was developed specifically for exterior preservation and sealing. It can be applied at temperatures as low as 0°F. It should perform satisfactorily over a temperature range of -65°F to +140°F. It is an excellent general-purpose tape for exterior preservation and sealing operations. Q36. Q37. Q38. Q39. Q40. Q41. State the levels and terms of preservation used for naval aircraft. What level of preservation is required if an aircraft is scheduled to remain idle for more than 14 days but less than 28 days? MIL-C-16173, corrosion preventive compound, is available in three grades. Which grade(s) is/are easily removed with dry-cleaning solvent? Corrosion-preventive petroleum, class 3, provides protection for what type of surfaces? When is general-purpose lubrication oil VV-L-800 used? What type of corrosion-preventive compound MIL-C-81309 is used on avionics and electrical equipment? ENGINE PRESERVATION NAVAIR 15-01-500, Preservation of Naval Aircraft, addresses specific requirements for the cleaning, inspection, protection, maintenance, and depreservation of auxiliary power units, gas turbine engines, and reciprocating engines. This section only highlights some important factors in engine preservation. Refer to the Preservation Manual for specific details. Level I preservation of engines requires the fuel system to remain at least 95% full of fuel for a period not to exceed 60 days. Any fuel system that has been drained of fuel for more than 3 days or is expected to remain inactive for more than 60 days is to be preserved with MIL-L-6081 Grade 1010. and be dehumidified. Level II and III preservation requirements are also outlined in the Preservation Manual. All requirements are listed by type engine and level of preservation desired. NOTE: In any case of preservation, ensure all logbook entries and preservation tag requirements have been met. SUPPORT EQUIPMENT PRESERVATION WARNING Do NOT use oil-based preservatives around oxygen fittings or oxygen regulators since fire or explosion may result. The preservation of clean, corrosion-free surfaces is the final step of the preventive maintenance process of SE. The act of preservation helps to protect nonmoving parts by filling air spaces, displacing water, and providing a barrier to corrosion. Preservatives For SE Preservatives are used after SE cleaning before ocean assignment when an extended period of SE storage is anticipated. Preservatives are also used wherever paint films require additional preservative (for example, in metal joints, tightly fitting surfaces, and on sump areas). The technical corrosion manual to be used for support equipment is Ground Support Equipment Cleaning And Corrosion Control, 4-18

NAVAIR l7-1-125. This publication takes precedence over any and all MIMs and service instruction manuals (SIMs) at both O- and I-level maintenance activities. This manual spells out specifically which materials and procedures you are to use to clean up corrosion and restore the protective surface. You still follow the maintenance and service manuals in conjunction with matters not pertaining to corrosion control. The four primary preservative compounds recommended for use on SE are listed in table 4-1. Apply corrosion-preventive compound to all exposed SE hardware items (around light brackets, hand brakes, levers, dissimilar metal joints, and tightly fitting surfaces and so forth). Preserve areas and components according to the following general procedures: 1. After removing corrosion products, clean the surface and spray the area with water-displacing agent, MIL-C-81309, type II. 2. Apply an even, thin coating of corrosion- preventive compound, MIL-C-16173, grade 4, or MIL-C-85054 to all nonmoving, difficult-to-protect areas. Use only MIL-C-16173, grade 4, for fasteners. 3. Dip removable screws and fasteners in corrosion-preventive compound before installation. 4. Remove excess compound from the metal surface with solvent, P-D-680, and clean cloth, DDD-R-30. Sealants For SE Sealants are brush- or spatula-applied compounds for SE corrosion prevention. These compounds are used primarily to repair damaged door and cover weather seals, fill depressions resulting from corrosion repair, protect heavy bolts and fasteners, and seal corrosion-prone crevices and lap seals. Two sealants recommended for SE are Silicone Sealant MIL-A-46146, type I, and Polysulfide Sealant MIL-S-81733 (inhibited) or MIL-S-8802 (uninhibited). When properly applied, the sealant forms as a barrier to the penetration of moisture. Prepare metal surfaces carefully before the application of a sealant. Do NOT apply sealant over visible moisture. Ensure that the sealant forms a continuous film at all seams, especially where dissimilar metals are in contact. When applying sealants on SE, you should use the following steps: 1. Mix the sealant according to the manufacturer’s direction. 2. Dip bolts or fasteners into the sealant so that the threads and shanks are completely covered. Immediately install the bolt in tapped holes. 3. Brush or swab sealant on mating surfaces that form a crevice when assembling parts. Immediately assemble these parts. 4. Pour, spoon, or trowel sealant into crevices that cannot be disassembled for treatment. Q42. What level of engine preservation requires the fuel system to remain at least 95 percent full of fuel for a period not to exceed 60 days? Q43. What technical corrosion manual should you use for support equipment? Q44. What are the two sealants recommended for use on support equipment? Table 4-1.—SE Preservatives Preservative compound Use Corrosion-Preventive Compound, Water-displacing, For all exposed metal and hardware not Ultrathin Film, MIL-C-81309, type II, class 2 exposed to the elements Corrosion-Preventive Compound, Water- Displacing, Clear, A general exterior surface preservative to MIL-C-85054, type I (AMLGUARD) produce an even, thin, nontacky, and clear film Corrosion-Preventive Compound, Solvent Cutback, Cold A general external preservative, which Application, MIL-C-16173, grade 4 produces a semitransparent film Corrosion-Preventive Compound, Ultrathin Film, Avionics A general preservative for internal areas of Grade, MIL-C-81309, type III electric components 4-19

CORROSION DETECTION LEARNING OBJECTIVE: Identify the types, forms, and characteristics of corrosion. Timely detection of corrosion is essential to any corrosion control program. Of course, corrosion can be detected after a part fails (if the equipment can be recovered). However, then it is too late to do anything about it other than to intensify inspections of other similar aircraft and SE. Inspection for corrosion should be a part of all routine inspections. On every aircraft and piece of SE, there are certain areas that are more corrosion prone than others. You should check these areas carefully. For the corrosion inspection to be thorough, you must know the types of corrosion likely to be found and the symptoms or appearance of each type of corrosion. Sometimes corrosion is hidden, and special detection methods are used to find it. Various aspects of corrosion detection are discussed in the following text. FORMS OF CORROSION Corrosion may occur in several forms, depending upon the specific function, size, shape and type of metal involved. Atmospheric conditions and the presence of corrosion-producing agents are also factors in the development of corrosion. The types of corrosion described in this section are the more common forms found on aircraft structures and SE. This text uses the most commonly accepted terms that describe the various types of corrosion. Uniform (Direct) Surface Attack The surface effect produced by the direct reaction of a metal surface with oxygen in the air is a uniform etching of the metal. The rusting of iron and steel, the tarnishing of silver, and the general dulling of aluminum surfaces are common examples of surface attack. On aluminum surfaces, if the surface attack is allowed to continue, the surface will become rough and eventually frosted in appearance. Figure 4-8 shows direct surface corrosion on an A-6 landing gear linkage system. Pitting Corrosion The most common effect of corrosion on aluminum and magnesium alloys is called “pitting.” The primary cause of pitting is the variation in structure or quality between areas on the metal surface in contact with a corrosive environment. Pitting corrosion is first noticeable as a white or gray powdery deposit, similar to dust, which blotches the surface. When the superficial deposit is cleaned away, tiny pits or holes can be seen in the surface. They may appear as shallow indentations or deep cavities of small diameter. Pitting may occur in any metal, but it is particularly characteristic of aluminum and magnesium. Figure 4-9 is an illustration of pitting corrosion. Crevice Attack or Concentration Cell Concentration cell corrosion is actually a form of pitting corrosion. Concentration cell corrosion is caused by the difference in concentration of the electrolyte or the active metal at the anode and cathode. When there are concentration differences at two different points in an entrapped pool of water or cleaning solution , anodic and cathodic areas may result. This results in the anodic area being attacked. Figure 4-10 shows the theory of concentration cell corrosion. Areas where there are crevices, scale, surface deposits, and stagnant water traps are prone to this type of attack. Concentration cell corrosion is controlled and prevented by avoiding the creation of crevices during repair work. It is also controlled with sealants and caulking compounds that eliminate voids that trap water. Intergranular Attack, Including Exfoliation All metals consist of many tiny building blocks called “crystals” (sometimes called grains). The boundaries between these crystals are commonly called “grain boundaries.” Intergranular corrosion is an attack on the grain boundaries of some alloys under specific conditions. During heat treatment, these alloys are heated to a temperature that dissolves the alloying elements. As the metal cools, these elements combine to form compounds. If the cooling rate is slow, they form at the grain boundaries. These compounds differ electrochemically from the material adjacent to the grain boundaries, and they can be either anodic or cathodic to the adjoining areas, depending upon their composition. The presence of an electrolyte results in attack of the anodic area. This attack can be rapid and exist without visible evidence. As the intergranular corrosion progresses to the more advanced stages, it lifts the surface grain of the 4-20

205.153Figure 4-8.—Surface corrosion on hydraulic linkage. metal. This is caused by the force of expanding corrosion products at the grain boundaries just below the surface. This advanced attack is called exfoliation (fig. 4-11). At this point, it can be seen by maintenance personnel. Correction of such serious corrosion is vital to aircraft safety. The insidious (sneaky) nature of such an attack can seriously weaken structural members before the volume of corrosion products accumulate on the surface and the damage becomes apparent. Metal that has been properly heat-treated is not readily prone to intergranular attack. However, localized overheating, such as could occur from welding and fire damage, can make metal prone to attack. If the intergranular attack has not penetrated so far as to impair structural strength, correction as outlined in the applicable structural repair manual (SRM) can restore an aircraft to flight status. Dissimilar Metal Corrosion The terms galvanic or dissimilar metal corrosion are applied when accelerated corrosion of metal is caused by dissimilar metals being in contact in a corrosive medium, such as salt spray or water. Dissimilar metal corrosion is usually the result of a 4-21

205.154 Figure 4-9.—Pitting of an aluminum wing assembly. Figure 4-10.—Concentration cell corrosion. faulty design or improper maintenance practices. You To keep these metals from coming in direct can usually recognize it by the presence of a buildup contact with each other, aircraft and support of corrosion at the joint between the metals. For equipment manufacturers use a variety of separating example, aluminum and steel materials riveted materials. Such materials include plastic tape, sealant, together in an aircraft wing form a galvanic couple if primer, washers. and lubricants. These materials keep moisture or contamination is present. When aluminum corrosion to a minimum. These separating materials pieces are attached with steel bolts or screws, galvanic must remain intact and be replaced, restored. or corrosion can occur around the fasteners (fig. 4-12). repaired as needed. 4-22

Figure 4-11.—Intergranular corrosion. Figure 4-12.—Galvanic corrosion. 4-23

Some metals are more active than others. The degree of attack depends upon the relative activity of the two surfaces in contact. The more active or easily oxidized surface becomes the anode and corrodes. In plated metal, the possibility of dissimilar metal corrosion becomes a factor only if there are defects in the plating. Moisture penetrates and galvanic cells form because of these defects. Stress Corrosion Stress corrosion is caused by the combined effects of tensile stress and corrosion. Stress may be internal or applied. Internal stresses are produced by nonuniform deformation during cold working, by unequal cooling from high temperatures during heat treatment, and by internal structural rearrangement involving volume changes. Stresses set up when a piece is formed. Stress induced by press-and-shrink fits and those in rivets and bolts are examples of internal stresses. Concealed stress is more important than design stress because it is difficult to recognize before it exceeds the design safety factor. The magnitude of the stress varies from point to point 4-24 Figure 4-13.—Stress corrosion cracking. within the metal. Stresses that approach the yield strength of the metal promote stress cracking (visible at this point), but failure can occur at lower stresses (fig. 4-13). Most often, stress cracks are not visible to the naked eye and are discovered in the nondestructive inspection (NDI) process. Fatigue Corrosion Fatigue corrosion is a special kind of stress corrosion. It is caused by the combined effect of corrosion and stress applied in cycles to a component. An example of cyclic stress is the alternating loads to which the reciprocating rod on the piston of a hydraulic, double-acting, actuating cylinder is subjected. During the extension stroke, a compression load is applied. During the retracting or pulling stroke, a tensile or stretching load is applied. Fracture of a metal part due to fatigue corrosion commonly occurs at a stress far below the fatigue limit in a laboratory environment, even though the amount of corrosion is unbelievably small. This is why protection of parts subject to alternating stress is particularly important in any environment. Figure 4-14 shows an oil cooler blower that disintegrated because of fatigue corrosion of a blade (shown by arrow). Fretting Corrosion Fretting corrosion is a limited but highly damaging type of corrosion. It is caused by a slight vibration, friction, or slippage between two contacting surfaces that are under stress and heavily loaded. It is usually associated with machined parts. Examples of these parts are the area of contact of bearing surfaces, two mating surfaces, and bolted or riveted assemblies. At least one of the surfaces must be metal. In fretting corrosion, the slipping movement on the contacting surface destroys the protective films that are present on the metallic surface. This action removes fine particles of the basic metal. The particles oxidize and form abrasive materials, which further agitate within a confined area to produce deep pits. Such pits are usually located in an area that increases the fatigue failure potential of the metal. Early signs of fretting corrosion are surface discoloration and the presence of corrosion products in lubrication. Lubrication and securing the parts so that they are rigid are effective measures to prevent this type of corrosion. 205.157

205.158 Figure 4-14.—Oil cooler blower disintegration. Filiform Corrosion Filiform corrosion (fig. 4-15) consists of threadlike filaments of corrosion known as underfilm. Metals coated with organic substances, such as paint films, may undergo this type of corrosion. Filiform corrosion occurs independently of light, metallurgical factors, and microorganisms present. It takes place when the relative humidity of the air is 78 to 90 percent and when the surface is slightly acidic. Although the threadlike filaments are visible only under clear lacquers or varnishes, they also occur under opaque paint film. Filiform corrosion can attack steel, aluminum, and magnesium. Microbiological Corrosion Microorganisms contained in seawater can be introduced into fuel systems by contaminated fuel. These fungus growths attack the sealing material used on integral fuel tanks. They can cause corrosion of aluminum, probably by aiding in the formation of concentration cells. Residues from biological growth tend to clog fuel filters and coat fuel quantity probes. Fuel quantity probes thus coated give erroneous readings. Also, moisture aides in the growth of fungi and microorganisms in avionic equipment. Q45. The tarnishing of silver is a common example of what type of corrosion? Q46. Pitting is the most common effect of corrosion on what alloys? Q47. Pitting corrosion is first noticeable as what color deposit on a metal surface? Q48. How can concentration cell corrosion be controlled or even prevented? Q49. Define intergranular corrosion. 4-25

205.159 Figure 4-15.—Filiform corrosion found under paint coating. Q50. What is usually the cause of dissimilar metal corrosion? Q51. What are some examples of internal stress corrosion? Q52. What causes fatigue corrosion? Q53. What is the cause of fretting corrosion? Q54. Filiform corrosion occurs on what types of metals? LOCATION OF CORROSION- PRONE AREAS LEARNING OBJECTIVE: Describe the areas on an aircraft prone to corrosion. This section discusses corrosion-prone areas common to all aircraft. For specific aircraft, you should refer to the periodic maintenance information cards (PMICs) to locate corrosion-prone areas for that aircraft. Figure 4-16 is an example of possible trouble spots on jet engine aircraft. Lavatories and galleys are likely trouble spots if they are not kept clean. These areas include the deck behind lavatories, sinks, and ranges where spilled food and waste products may accumulate. Even when contaminants are noncorrosive: they may attract and hold moisture. This, in turn, causes corrosive attack. Maintenance personnel should pay attention to bilge areas located under galleys and lavatories and to personnel relief and waste disposal vents or openings on the aircraft exteriors. Human waste products can corrode common aircraft metals. Avionic Systems The control of corrosion in avionic systems is not unlike that in airframes. Procedures useful for airframes apply to avionics, with appropriate modifications. Avionics systems are more prone to corrosion than aircraft because avionics have the following characteristics: Less durable protection systems, Very small amounts of corrosion can make equipment inoperative. Dissimilar metals are often in electrical contact. Stray currents are present that can cause corrosion. 4-26

1. Radome area 2. Rudder petal 3. Cockpit floor 4. Battery compartment 5. Piano hinges 6. Flight control cables 7. Exhaust areas 8. Missile rocket blast area 9. Flap carriage area 10. Magnesium wheels 11. Exposed rigid tubing 12. Main wheel well 13. Air inlet ducts and engine frontal areas 14. Nose wheel well Figure 4-16.—Typical corrosion-prone areas on jet engine aircraft. Active metals and dissimilar metals in contact are often unprotected. Closed boxes can produce condensation during normal temperature changes during flight. Avionic systems have many areas to trap moisture. Hidden corrosion is difficult to detect in many avionic systems. Many materials used in avionic systems are subject to attack by bacteria and fungi. Organic materials are often used that, when overheated or improperly or incompletely cured, can produce vapors. These vapors are corrosive to electronic components and damaging to coatings and insulators. The only requirements for a corrosion cell are a cathode, an anode, and an electrolyte. The size of a cell depends upon the size of its components. A cell can form where a resistor lead is soldered to a terminal, or where two sheets of metal join. It can also form around a rivet head and the adjacent metal. (See figure 4-17, views A and B.) Even two metallic crystals in the same alloy can form a cell. All that is needed is for crystals to be of different composition and in electrical contact with each other in the presence of an electrolyte (fig. 4-17, view C). Battery Compartments and Battery Vent Openings. Fumes from battery electrolyte are difficult to contain. They will spread throughout the battery compartment, vents, and even adjacent internal cavities. Battery electrolyte fumes cause rapid corrosive attack on unprotected surfaces. Maintenance personnel should check the external skin area around the vent openings regularly for this type of corrosion. Corrosion from this source is a serious problem 4-27

228.53 Figure 4-17.—Electrochemical corrosion. whenever batteries are used. The battery compartment shown in figure 4-18 needs immediate attention. WARNING Before performing any cleaning, inspec- tion, or maintenance on electrical systems, maintenance personnel should make sure that all electrical power is secured from the air- craft. If the electrical power is NOT secured from the aircraft, it could result in serious injury to maintenance personnel. Multiple Electrical Connectors (Cannon Plugs). Connectors mounted in avionic and electrical systems are prone to the same corrosive environment as airframe structural components (fig. 4-19). Normally, connectors and mounting plates contain a gasket that acts as a watertight seal. When maintenance personnel dismantle (take apart) a connector for cleaning or repair, they should inspect the gasket. They should give special attention to connectors that use replaceable pins. These connectors use a self-sealing gasket water seal or dog bones (plastic inserts) that automatically seal the connectors against water intrusion. The repeated removal and replacement of the pins or forgetting the dog bones may cause the watertight seal to lose its effectiveness. In extreme cases where the connector cannot be replaced, potting compounds must be used to prevent water intrusion. You can find the stock numbers for dog bones in the applicable IPB. Coaxial Connectors. Look at figure 4-20. It shows corrosion on a coaxial connector. Coaxial connectors require special steps to avoid water intrusion. Usually, moisture, contaminants, and corrosion in fuel quantity, oil quantity, and similar capacitive-type indicating system connectors cause erroneous (wrong) quantity indications in the cockpit indicating systems. Antenna coaxial connectors have similar problems with moisture. Wire Harnesses and Cables. When corrosion is discovered at the pin-to-wire connection on electrical connectors, plugs, and receptacles, the wire harness 4-28

205.160Figure 4-18.—Battery compartment. and cables should be inspected for corrosion attack and cracking of the wire insulation. Cable shielding is particularly prone to corrosion. Ram Air Turbine (Rat) Compartments. Maintenance personnel should inspect RAT compartments for moisture traps. They should inspect all mounting hardware, electrical connectors, terminal boards, junction boxes, and the RAT itself for signs of corrosion that may have been caused by moisture spray. Electrical Bonding and Grounding Straps. The bonding and grounding straps used on aircraft and electrical equipment are major sources of galvanic corrosion. Usually, this strap is made of a metal that is dissimilar to the areas to which it is attached. Thus, a galvanic couple is created. Unless maintenance personnel take proper preservation action, this couple, in the presence of moisture, corrodes at a rapid rate. 4-29

205.161 Figure 4-19.—Corrosion on control box electrical connectors. 205.162 Figure 4-20.—Corrosion on coaxial connector. Light Assemblies. External formation lights, wing tip lights, rotating beacons, and lower fuselage anticollision lights are highly prone to corrosion. These lights are prone to corrosion because of poor seals, exposure to the elements in flight, or water intrusion during aircraft washdown. Usually, corrosion is heavy at the bases of the bulbs because of dissimilar metal contact between bulbs and sockets. Seals and preservation actions reduce the likelihood of corrosion in light assemblies. Q55. The corrosion-prone areas for each specific aircraft are derailed in what publication? Q56. What are the three requirements for a corrosion cell to form? Ejection Seats Aboard ship, salt spray enters most aircraft cockpit areas when the canopies are opened for respotting of aircraft maintenance or to accommodate the manning of ready alert aircraft. While the cockpit and ejection seats are not as corrosion prone as some other areas, they are still in a corrosive environment. Therefore, the cockpit and ejection seats require constant attention, along with other parts of the aircraft. Because of their construction and location, ejection seats are difficult to inspect and clean thoroughly while they are installed in the aircraft. Also, there is a lengthy period of time between aircraft inspections that require seat removal. Therefore, 4-30

205.164 Figure 4-21.—Corrosion-prone point of air inlet duct. ejection seats could become severely corroded if not given adequate attention. The likelihood that slight corrosion could make an ejection seat inoperable must not be overlooked. The MRCs for these seats require that every portion of the seats be checked thoroughly for corrosion when they are removed from the aircraft. Additional emphasis is usually given to the ultrahigh-strength steel parts of seats. As with all aircraft parts, corrosion could weaken the structural soundness of a seat. Maintenance personnel should give worn paint finishes and those showing signs of superficial corrosion immediate attention, as specified in the applicable MIM, because other problems not yet visible may be present. They should touch up cockpit fasteners with dull, black paint to prevent cockpit glare. Refer to NAVAIR 01-1 A-509 for more information. Intake and Exhaust Trail Areas Airborne dirt and dust and bits of gravel from runways constantly erode engine frontal areas and cooling air vents. Rain erosion removes the protective finish on intake and exhaust areas (fig. 4-21). In addition, areas such as air intake ducts and cooler radiator cores are not painted. Engine accessory mounting bases usually have small areas of unpainted magnesium or aluminum on the machined mounting surfaces. With moist, salt-laden air constantly flowing over these surfaces, they are prime sources of a corrosive attack (fig. 4-22). When maintenance 205.165 Figure 4-22.—Corrosion in air intake duct. 4-31

personnel inspect such areas, they should also inspect all sections in the cooling air path, giving special attention to obstructions and crevices where salt deposits may build up during marine operations. Corrosion must be checked in its early stages and paint touch-up and hard-film, preservative coatings must be maintained intact. Jet exhaust deposits are very corrosive. These deposits are particularly troublesome where gaps. seams, hinges, and fairings are located down the exhaust path, and where the deposits may be trapped and not reached by normal cleaning methods. When inspecting these surfaces, maintenance personnel should give special attention to the areas indicated in figure 4-23. Maintenance personnel should also include in their inspection procedures the removal of fairings and access panels located in the exhaust path. JATO, Rocket, and Gun Blast Areas Surfaces located in the path of JATO, rocket, and gun blasts are particularly subject to corrosive attack and decay (fig. 4-24). In addition to the corrosive effect of the gases and exhaust deposits, protective finishes are often blistered by heat and blasted away by high-velocity gases. Also, spent shell casings or solid particles from gun and rocket exhausts abrade finishes. Maintenance personnel should watch these areas for corrosion and clean the finishes carefully after firing operations. Bilge Areas Bilge areas are common trouble spots on all aircraft. One example of a bilge area is the engine bay area. Bilge areas are natural collection points for waste. hydraulic fluids, water, dirt, loose fasteners, drill shavings, and other debris. Oil puddles often mask small quantities of water, which settle to the bottom and set up hidden corrosion cells. Keeping bilge areas free of extraneous material, including oil, is the best insurance against corrosion. Wheel Wells and Landing Gear The wheel well area probably receives more punishment than any other area on the aircraft. It is exposed to mud, water, salt, gravel, and other flying debris from runways during flight operations. It is open to salt water and salt spray when the aircraft is parked aboard ship. Because of the many complicated shapes, assemblies, and fittings in the area, complete coverage with a protectile paint film is difficult to attain. Because of the heat generated from braking, Figure 4-23.—Exhaust trail corrosion points. 4-32

Figure 4-24.—Gun blast area corrosion points. preservative coatings are not used on jet aircraft landing gear wheels. During inspections, maintenance personnel should pay particular attention to the following areas: Magnesium wheels, especially around bolt heads, lugs, and wheel well areas Exposed metal tubing, especially at nuts and ferrules, and under clamps and identification tapes Exposed connectors, such as indicator switches and other electrical equipment Crevices between stiffeners, ribs, and lower skin surfaces, which are typical water and debris traps Water Entrapment Areas Aircraft have drains installed in areas where water may collect. However, these drains may not be effective either because of improper location or because they are plugged by sealants, fasteners, dirt, grease, and debris. Daily inspection of drains is a standard requirement, especially aboard ship. Q57. Cockpit fasteners should be touched up with what color paint? Q58. In water entrapment areas of an aircraft, drains are required to be inspected how often? Wing Fold, Flap, and Speed Brake Recesses Flap and speed brake recesses are potential corrosion problem areas because they are normally closed when on the ground. Dirt and water may collect and go unnoticed. Wing fold areas contain complicated shapes and assemblies that are difficult to cover with a protective paint coating or preservative film; thus, corrosion is present. Wing fold areas are extra vulnerable to salt spray when wings are folded aboard ship. To thoroughly inspect this area, maintenance personnel should use a mirror to check the back sides of tubing and fittings. Also, they should pay particular attention to aluminum alloy, wing lock fittings (such as those used in some current aircraft models). External Skin Areas Most external aircraft surfaces are ordinarily covered with protective paint coatings and are readily visible or available for inspection and maintenance. Even here, certain types of configurations or combinations of materials can cause trouble under shipboard operating conditions and require special attention. Magnesium skin, when painted over, is not visibly different from any other painted metal surface. Magnesium surfaces are identified in the applicable structural repair manual. When an aircraft contains 4-33

magnesium skin panels, maintenance personnel must give special attention to these panels during inspections for corrosion. Some aircraft have steel fasteners installed through magnesium skin with only protective finishes under the fastener heads or tapes over the surface for insulation. In addition, paint coatings are thin at trimmed edges and comers. These conditions, coupled with magnesium’s sensitivity to saltwater attack, present a potential corrosion problem whenever magnesium is used. Therefore, maintenance personnel must inspect all magnesium skin surfaces for corrosion, giving special attention to edges, areas around fasteners, and cracked, chipped, or missing paint. The entrance and entrapment of corrosive agents between the layers of metal cause corrosion of spot-welded skins. (See figure 4-25.) Some of the corrosion may be caused originally by fabrication processes, but its progress to the point of skin bulging and spot-weld fracture is the direct result of moisture or salt water working its way in through open gaps and seams. The first indication of this type of corrosion is the appearance of corrosion products at the crevices where the corrosive agents entered. Corrosion may appear at the external or internal faying (closely joined) surfaces, but it is usually more prevalent on external areas. More advanced corrosive attack causes skin buckling and eventual spot-weld fracture. Maintenance personnel should detect skin buckling in its early stages by sighting along spot-welded seams or by using a straightedge. Piano-Type Hinges Figure 4-26 shows the effect of corrosion on the piano hinges used on aircraft. These are prime spots for corrosion to develop due to the dissimilar metal contact between the steel pin and aluminum hinge tangs. They also natural traps for dirt, salt, and moisture. When used on access doors and plates, these hinges tend to freeze in place because they are opened only during periodic inspections. While inspecting for corrosion of these hinges, maintenance personnel should lubricate the hinge and move the hinge back and forth several times to ensure complete penetration of the lubricant. RECOGNIZING AND ELIMINATING CORROSION One of the problems you will have as a maintenance crew member is recognizing and combating corrosion on different materials. The following paragraphs include brief descriptions of typical corrosion product characteristics that are normally found on the materials used in aircraft construction. Also included are the normal procedures for their elimination and prevention. Treating internal corrosion of equipment requires a trained technician, and is normally accomplished at the intermediate- maintenance level. The materials found in avionic equipment, such as gold, silver, tin, solder, and copper alloys, are prone to many forms of corrosion. The treatment for corrosion involving these materials can be found in NAVAIR 16-l-540. When in-depth information is needed about structural corrosion, refer to NAVAIR 01-1A-509. Table 4-2 identifies the Figure 4-25.—Spot-welded skin corrosion points. 4-34

Table 4-2.—Corrosion of Metals—Nature and Appearance of Corrosion Products ALLOY TYPE OF ATTACK TO WHICH APPEARANCE OF ALLOY IS SUSCEPTIBLE CORROSION PRODUCT Aluminum Alloy Surface pitting, intergranular, White to gray powder. exfoliation, stress corrosion, fatigue cracking and fretting. Titanium Alloy Highly corrosion resistant. Extended No visible corrosion products at low or repeated contact with chlorinated temperature. Colored surface oxides solvents may result in degradation develop above 700°F. of the metal's structural properties. Magnesium Alloy Highly susceptible to pitting. White powder snowlike mounds and white spots on the surface. Carbon and Low-Alloy Steel Surface oxidation and pitting, Reddish-brown oxide (Rust). surface and intergranular. Stainless Steel Crevice/concentration cell Rough surface; sometimes a red, (300-400 series) corrosion; some pitting in marine brown, or black stain. environments; corrosion cracking; intergranular corrosion (300 series) and surface corrosion (400 series). Nickel-base Alloy Generally has good Green powdery deposit. (Inconel, Monel) corrosion-resistant qualities; susceptible to pitting in seawater. Copper-base Alloy Surface and intergranular corrosion. Blue or blue-green powdery deposit. Brass, Bronze Cadmium (protective plating for Good corrosion resistance. Will White powdery deposit to steel) cause embrittlement if not properly brown/black mottling of the surface. applied. Chromium (wear-resistant plating Subject to pitting in chloride Chromium being cathodic to steel, for steel) environments. does not corrode itself, but promotes rusting of steel where pits occur in the coating. Silver Will tarnish in presence of sulfur. Brown to black film. Gold Highly corrosion resistant. Deposits cause darkening of reflective surfaces. Tin Subject to whisker growth. Whiskerlike deposits. nature and appearance of corrosion products found on the metals used in aircraft construction. Iron and Steel Possibly the best known and the most easily recognized form of metals corrosion is the familiar reddish-colored iron rust. When iron and its alloys corrode, dark iron oxide coatings usually form first. These coatings, such as heat scale on steel sheet stock, may protect iron surfaces. However, if enough oxygen and moisture are present, the iron oxide is soon converted to hydrated ferric oxide, commonly known as iron rust. Iron and steel are used in avionic equipment as component leads, magnetic shields, transformer cores, racks, and general hardware. Steel and iron hardware used in aircraft construction is usually plated with nickel, tin, or cadmium. Aluminum Aluminum and its alloys are used many places in aircraft construction, including ejection seats, chassis 4-35

205.200 Figure 4-26.—Hinge corrosion points. structures in avionic equipment, and the skin of the aircraft. Because of its wide use, you must be able to recognize and take the proper corrective action whenever corrosion is detected or suspected. Aluminum and its alloys are subject to a wide range of corrosive attack, varying from general etching of the surfaces to penetrating attacks along the internal grain boundaries of the metal. The corrosion products (fig. 4-27) appear as white-to-gray powdery deposits that have greater volume than the original metal. In its early stages, aluminum corrosion is evident as a general etching, pitting, or roughness of the surface. The surface attack progresses quite slowly at first; however, the attack will accelerate if the corroding material is not given immediate attention. Paint coatings mask evidence of corrosion, but because the corrosion products have a greater volume, corrosion will show up as blisters, flakes, chips, lumps, or other irregularities in the paint coating. Often, white or gray streaks of corrosion products become readily apparent at breaks in the paint film. Maintenance personnel should investigate such signs further to determine the extent that corrosion has progressed. There are three types of aluminum surfaces insofar as corrosion removal is concerned. They are clad, anodized, and exfoliated aluminum surfaces. Clad Aluminum Surfaces. Pure aluminum has considerable corrosion resistance compared to aluminum alloys. but it has little or no structural strength. An extremely thin sheet of pure aluminum laminated onto each side of an aluminum alloy sheet improves the corrosion resistance with little impairment of strength. The trade name of this aluminum laminate, as originated by the Aluminum Company of America, is Alcad. From this trade name the adjective clad and the verb cladding have been derived. An example of clad aluminum is the surface of unpainted aircraft. Not all aircraft sheet aluminum is clad, especially those alloy sheets from which small brackets, gussets, and fittings are made. The pure aluminum is very soft, and fabrication processes would severely damage or destroy the clad surfaces. To remove corrosion from clad surfaces, the corroded areas should be hand polished with MIL-P-6888 metal polish. It effectively removes stains and produces a high-gloss, lasting polish on unpainted clad surfaces. During the polishing operation, you should take care to avoid mechanical 4-36

205.166 Figure 4-27.—Aluminum corrosion products. removal of the protective clad layer and exposure of the more susceptible, but stronger, aluminum alloy base. If there is any superficial corrosion present, you should treat it by wiping down the surface with an inhibitive material, such as the Chemical Surface Films for Aluminum Alloy, available under specification MIL-C-81706. Anodized Aluminum Surfaces. Nonclad aluminum alloys are the primary type of aluminum used on naval aircraft. Anodizing is the most common surface treatment of nonclad aluminum alloy surfaces. In anodizing aluminum alloys, the alloy sheet or casting is the positive pole in an electrolytic bath in which an oxidizing agent produces an aluminum oxide film on the metal surface. This aluminum oxide is naturally protective, and anodizing merely increases the thickness and density of the natural oxide film. When this coating is damaged in service, it can only be partially restored by chemical surface treatments. Therefore, when processing anodized surfaces, including corrosion removal, you should avoid destruction of the oxide film. Aluminum wool (nylon webbing impregnated with aluminum oxide abrasive) or fiber bristle brushes are the approved tools for cleaning anodized surfaces. The use of steel wool, steel wire brushes, or harsh abrasive materials on aluminum surfaces is prohibited. A buffed or wire brush finish produced by any means is also prohibited. Otherwise, anodized surfaces are treated in much the same manner as other aluminum finishes. Exfoliated Surfaces. As previously described, exfoliation is a separation along the grain boundaries of metal and is caused by intergranular corrosion. More severe procedures must be used when intergranular corrosion is present. All corrosion products and visible delaminated metal layers must be removed by mechanical means to determine the extent of destruction and to evaluate the remaining structural strength of the component. Maintenance personnel use metal scrapers, rotary tiles, and other tools to assure that all corrosion products are removed and that only structurally sound aluminum remains. Maintenance personnel should inspect the area with a 5- to 10-power magnifying glass or use a dye penetrant to determine if all unsound metal and corrosion products have been removed. When all corrosion products have been removed, maintenance personnel should blend or smooth out any rough edges, even if it involves the removal of more metal. Grinding, where required, is best done by using abrasive nylon wheels into which tiny particles of aluminum oxide abrasives have been impregnated. Chemical treatment of exposed surfaces is applied in the same manner as any other aluminum surface. An aeronautical engineer should evaluate any loss of structural strength in critical areas. This is particularly true if the damage exceeds the permissible limits established in the structural repair manual for the aircraft model involved. Magnesium Magnesium and its alloys have limited use in aircraft structural construction. However, they are used extensively throughout avionic systems as antennas, structures, chassis, supports, and frames. Magnesium, without a protective coating, is highly susceptible to corrosion when exposed to marine environments. Magnesium forms a strong anodic galvanic cell with every other metal and is ALWAYS the one attacked. Magnesium is subject to direct acid 4-37

attack, deep pitting, stress corrosion, intergranular, and galvanic corrosion. Corrosion of magnesium or its alloys forms white, powdery, snowlike mounds. The deposits tend to raise slightly. and the corrosion spreads rapidly. When magnesium corrosion is detected, it requires immediate attention or the corrosion will spread throughout the entire structure. Magnesium corrosion reprotection involves the maximum removal of corrosion products, the partial restoration of surface coatings by chemical treatment, and a reapplication of protective coatings. After maintenance personnel clean the surface and strip the paint, (if any,) they break loose and remove as much of the corrosion products as possible. They do this by using a pneumatic drill with an abrasive wheel or a Vacu-Blast Dry Honing Machine with glass beads. Steel wire brushes. Carborundum™ abrasives, or steel-cutting tools should NOT be used. After corrosion removal, maintenance personnel treat the surface with specification MIL-M-3171 (type VI) chemical treatment solution, as outlined in the NAVAIR 01-1A-509. Then restore the protective paint film. If extensive removal of corrosion products from a structural casting was involved, a decision from a structural engineer may be necessary to evaluate the adequacy of the structural strength remaining. Structural repair manuals for the aircraft models involved usually include tolerance limits for dimensions of critical structural members. They should be referred to if any question of safety of flight is involved. Copper and Copper Alloys Copper and its alloys are generally corrosion resistant, although the products of corrosive attack on copper are commonly known. Sometimes copper or copper-alloy surfaces will tarnish to a dull gray-green color, and the surface may still be smooth. This discoloration is the result of the formation of a fine-grained, copper oxide crust called “patina.” The patina, in itself, offers good protection for the underlying metal in ordinary situations. However, exposure of copper and copper alloys to moisture or salt spray causes the formation of blue or green salts, indicating active corrosion. These salts form over the patina since this crust is not totally moistureproof. Copper alloys used in aircraft have a cadmium-plated finish to prevent surface straining and decay. Copper and copper-based alloys are used in avionic systems as contacts, springs, connectors, printed circuit board runs, and wires. Copper and copper-based alloys (brass and bronze) are resistant to atmospheric corrosion. However, copper is cathodic to iron, steel, aluminum, and magnesium when in electrical contact with these metals. Maintenance personnel can remove corrosion products by using a pneumatic drill with an abrasive wheel or, as an alternate method, a typewriter eraser (ZZ-E-661. type I or III), depending upon the situation. Copper and copper alloys used in avionic equipment are not usually painted. Cadmium and Zinc Cadmium is used as a coating to protect the part to which it is applied. It also provides a compatible surface when the part is in contact with other materials. The cadmium plate supplies sacrificial protection to the underlying metal because of its greater activity. That is, during the time it is protecting the base metal, the cadmium is intentionally being consumed. It functions in the same way that an active magnesium rod inserted in the water system protects the piping of a hot-water heater. The cadmium becomes anodic and is attacked first, leaving the base metal free of corrosion. Zinc coatings are used for the same purpose, but to a lesser extent in aircraft. Attack is evident by white-to-brown-to-black mottling of the cadmium surfaces. These indications DO NOT indicate decay of the base metal and should NEVER be removed for appearance sake alone. Until the characteristic colors peculiar to corrosion of the base metal appear, no steps should be taken, Cadmium is usually used on bolts as a sacrificial metal to protect the base metal. Zinc is used in avionic/electronic equipment for the same general purpose. Maintenance personne1 remove corrosion products by rubbing lightly with stainless steel wool, abrasive impregnated webbing, or 320-grit or finer aluminum oxide abrasive paper. They do not remove the undamaged cadmium plate adjacent to the corroded area; this will reduce the amount of protection for the underlying base metal. Wire brushes are not used on cadmium-plated surfaces since they will remove more plating than corrosion. After removing corrosion products from cadmium-plated surfaces, maintenance personnel apply a protective coating to retard the corrosive attack. 4-38

Nickel and Chromium Alloys Nickel and chromium alloys are also used as protective agents in the form of electroplated coatings. Also, they are used as alloying constituents with iron in stainless steels, such as the wear surfaces of aircraft struts. Nickel and chromium plates protect by forming a physical, noncorrosive barrier over the steel. Electroplated coatings, particularly chromium on steel, are slightly porous, and corrosion eventually starts at these pores or pin holes unless a supplementary coating is applied and maintained. Titanium Titanium is often used in engine exhaust areas. Titanium is a highly corrosion-resistant metal. However, it can greatly accelerate corrosion of dissimilar metal coupled to it. Insulation between titanium and other metals is necessary to prevent dissimilar metal attack on the other metal. Maintenance personnel must frequently inspect such areas to make sure that insulation failure has not allowed corrosion to begin. Q59. Q60. Q61. Q62. Q63. Q64. Q65. Q66. Q67. Q68. What publication should you refer to for information about structural corrosion? Hydrated ferric oxide is commonly known as what kind of corrosion? What are the three types of aluminum surfaces insofar as corrosion removal is concerned? How should you remove corrosion from clad aluminum surfaces? What is the primary type of aluminum used on naval aircraft? What are the approved tools for cleaning anodized aluminum surfaces? Who should evaluate any loss of structural strength in critical areas of an aircraft? What manual should you refer to for tolerance limits for dimensions of critical structural members? Copper and copper-based alloys are used in avionic systems for what purpose? Where is titanium most often used on a aircraft? CORROSION REMOVAL AND TREATMENT LEARNING OBJECTIVE: Describe the methods of removing and treating corrosion. Once corrosion is detected, a specific and immediate program for corrective treatment is required. A complete treatment involves paint removal and cleaning of all corroded areas, removal of corrosion products, restoration of protective, surface-treatment films, and immediate application of protective coating and paint finishes. Each type of corrosion has its own peculiarities and requires special treatment. Corrosion should always be removed by the mildest means available. CORROSION REMOVAL Before starting any corrosion removal, you must conduct an inspection and evaluation of the suspected area. When you inspect an aircraft or a particular area of an aircraft for corrosion, you should follow the steps listed below. 1. Clean the area thoroughly. 2. If an area is suspected of having corrosion, visually inspect the area by using a magnifying glass. 3. To preclude metal damage, remove paint chemically from areas suspected of having underlying hidden corrosion. Use abrasive paint removal techniques only when corrosive products are observed. 4. After removing the paint, use a magnifying glass to determine the extent of the damage, especially if there is evidence of corrosion on critical parts. Corrosion cracks must be detected as early as possible. 5. Refer to the applicable structural repair manual (SRM) or MIM for damage limits. Metal loss damage is accumulative. When assessing corrosion damage, consider prior metal loss, including areas on the opposite side of the part. Propellers and helicopter blades have critical balance requirements. Refer to the propeller and blade manuals that apply for the evaluation and repair limits of corrosion, erosion, and abrasive damage. After the aircraft or aircraft part has been inspected, the extent of the corrosion damage must be correctly evaluated. The severity of corrosion damage is grouped into the following categories: Light corrosion. This type of damage is defined as a protective coating that is scarred or etched by light 4-39

surface corrosion. characterized by discolorization and pitting to a depth of approximately, 1-mil (0.001 inch) maximum. This type of damage can normally be removed by light hand sanding. Moderate corrosion. This looks like light corrosion except that there may be some blisters or evidence of scaling and flaking of the coating or paint system. The pitting depths may be as deep as 10 mils (0.010 inch). This type of damage is normally removed by extensive hand sanding or light mechanical sanding. Severe corrosion. This type of corrosion has a general appearance that may be similar to moderate corrosion with severe intergranular corrosion, blistering exfoliation, scaling, or flaking. The pitting depths are deeper than 10 mils (0.010 inch). This damage must be removed by extensive mechanical sanding and grinding. Repairable damage. When corrosion damage exceeds the limits of the applicable MIM or SRM, it is classified as repairable damage. The use of the affected part may be continued after repair at a cognizant field activity (CFA). Nonrepairable damage. When corrosion damage exceeds the established repair limits and requires replacement of the affected parts or special depot-level repair, it is classified as nonrepairable damage. MECHANICAL CORROSION REMOVAL The most effective mechanical methods of removing corrosion with the least removal of the metal are vapor blasting, soft-grit blasting, and dry, vacuum blasting. For use on assembled aircraft, a portable unit, such as the VACU-Blast Dry Honing Machine, is the most desirable. VACU-Blast Dry Honer The VACU-Blast Dry Honing Machine is a portable, air-operated, self-contained, lightweight unit that uses the dry vacuum return system. Dry honing is the only approved blasting method of removing corrosion on assembled aircraft. With this machine, the work is visible, and metal removal can be held to closer limits. The machine is air-operated, and can be used in shore-based or shipboard operations. The dry honing machine (fig. 4-28) is composed of the following principal components mounted on a two-wheel carriage assembly: A hose rack and storage compartment is provided on the front of the dry honing machine for storage of hoses, brushes, and accessories. The dry honing machine can cause damage to aircraft components and systems if used improperly. Small quantities of abrasives will escape from the blast nozzle during normal use; therefore, the equipment must not be used where the abrasives may contaminate systems or components. The following are precautions you should use when working with this machine: Do not use on engines, gearboxes, or other oil lubricating systems. Do not use on fuel, hydraulic, or oxygen system components. Mask all vent susceptible systems when blasting near them to prevent possible contamination. Use only on exterior surfaces or parts that have been removed from the airframe to prevent possible contamination of interior areas. Do not use on airframe skins or structural parts that are exposed to more than 500°F in service. Do not blast Metallite or honeycomb panels. Q69. What must you do before starting corrosion removal? Q70. How should you remove moderate corrosion? Q71. What is the most desirable method of mechanical corrosion removal? Abrasive Wheel An abrasive wheel can be used to remove severe corrosion (intergranular or exfoliation) on thick metal. The abrasive wheel is composed of nonwoven nylon, resin reinforced. The wheel is mounted on a mandrel assembly and driven by a pneumatic drill motor. Eye protection must be worn when an abrasive wheel is operated. CAUTION After removal of exfoliation corrosion by abrasive wheel, VACU-Blast area with glass beads to ensure removal of all corrosion. Failure to do so will result in the formation of tiny bubbles or flakes. 4-40

Figure 4-28.—VACU-Blast dry honing machine. 4-41

SUPPORT EQUIPMENT (SE) CORROSION REMOVAL AND SURFACE PREPARATION The following text discusses surface preparation as well as mechanical and chemical paint and corrosion removal methods for SE. They are listed in order from the most effective or preferred to the least effective and not preferred. Each SE maintenance station develops the procedures for operating surface preparation equipment according to the applicable MIMs. The key to achieving a successful, long-lasting coating system lies in good bonding between coating and metallic surfaces of SE. Paint will not bond to a surface that is poorly prepared. Dirt, oil, grease, corrosion by-products, moisture, and other contaminants prevent complete contact between paint and base metal. In addition, a metallic surface must be roughened to enable the paint system to bond to the surface. This roughened or anchor pattern can be produced by mechanical means or by chemical etchings. You should remove corrosion, scale, and old paint from SE by the least destructive method. Where simple touch-up painting is required. feather the edges of existing sound paint with light sanding to provide an anchor for the touch-up paint. You must apply the initial paint to SE as soon as possible following surface preparation. A prolonged lapse in time between surface preparation and painting allows corrosion to form on the prepared surface. This corrosion will cause later coating system failure. REMOVING DIRT, OIL, AND GREASE The first step in surface preparation is the removal of dirt, salt, lubricants. hydraulic oil, and other surface contaminants from SE. When grease and oil are present during abrasive blasting, grinding, or wire brushing, they will spread out over the treated surface and disrupt the coating bond. The cleaning method that you use depends on the type of soil, its extent, and the available cleaning equipment. Detergent cleaning, solvent cleaning, emulsifiable solvent cleaning, and acid cleaning are cleaning or degreasing methods. Detergents and solvents are highly effective in attacking and dissolving grease and oil on metal surfaces of SE. Most solvents can be either applied by vapor degreasing equipment or by wiping. Solvents are specially useful for cleaning small parts and spot-cleaning jobs. Disadvantages of degreasers lie in their toxicity and flammability. Many solvents are particularly dangerous when used on oxygen service equipment. Emulsifiable solvent (solvents suspended in a gelatinlike medium) cleaning is an effective cleaning method for removing heavy oil, grease, wax, and other contaminants of SE. Acid cleaning combines the forces of oil solvents and detergent cleaners in removing grease, oil, light rust, and other contaminants. The method is useful on the heavy steel structures of SE where surface etching is required. This cleaning method requires a thorough rinse with clean water. MECHANICAL CORROSION REMOVAL ON SUPPORT EQUIPMENT (SE) Abrasive or grit blasting is the preferred surface preparation method for many of the components of SE. Such blasting provides the clean anchor pattern needed by most coating systems. Wet abrasive blasting is preferred to dry blasting. Before blasting, disassemble the components according to the applicable technical manual. Mask all areas that should not be blasted, such as tapped holes, key ways, machined surfaces, reflectors, lights, and gauges. When using abrasive blasting equipment, you must wear protective clothing, face shield or safety goggles, and a respirator. Wet Abrasive Blasting Water blasting is a technique that requires high-pressure producing equipment. It involves the propelling of water and blasting beads. The water blast method removes surface chemical contaminants, deteriorated paint, grease accumulations, oil, and mastic materials from SE. NOTE: You must use Sodium Nitrite MIL-S-24521 during the abrasive process to prevent flash rusting. The Hydroblaster or other water blast machines can be dangerous if not handled properly or with sufficient safeguards. 4-42

Dry Abrasive Blasting Dry abrasive blasting involves propelling abrasive particles against the metallic surface by either high-pressure air or spinning paddle wheel. The striking of these particles against the metal abrades away deteriorated paint and scale. Many abrasive blast machines (portable dry-honing machines) reclaim used grit by cleaning and sifting out dirt, scale, and damaged grit. (See figure 4-28.) Grit that has been recycled after use on steel, brass, bronze, or copper-nickel should not be used on aluminum. Do not blast aluminum with steel or copper slag or chilled iron grit. Table 4-3 lists some common abrasive materials and grit sizes. CLEANING SURFACES WITH POWER TOOLS Power tool cleaning includes devices that impact the metallic surface with an abrasive substance or mechanical object. Impact tools, powered wire brushes, and disk sanders are common power tool cleaners for SE. Usually, electric or pneumatic disk sanders abrade the metal surface of SE with coarse to fine grit. When used with the needle gun, the disk sander can produce a uniform anchor pattern of very closely spaced scratches. WARNING When using abrasive power hand tools, you must wear eye protection to prevent serious injury. Q72. What is the preferred surface preparation method for many of the components of support equipment? Q73. What should you use during the abrasive process to prevent flash rusting? CORROSION DAMAGE LIMITS LEARNING OBJECTIVE: Recognize the limits in removing corrosion damage. Impact tools, such as the needle gun (pneumatic descaler), provide a rapid means for removing rust and old paint from metal surfaces of SE. These tools must NEVER be used on aluminum. A wire brush powered pneumatically or by electric motor is a method for removing small amounts of paint and rust from SE. Often, the overextended use of a wire brush results in a metal surface that is polished to a glossy appearance. A polished surface produces a poor anchor pattern for paint bonding. Corrosion damage limits refer to the amount of metal that may be removed from a corroded part without impairing the strength and function of the part. When removing corrosion, maintenance personnel must be very careful not to remove more of the metal than is necessary to ensure complete removal of corrosion. Figure 4-29 shows the maximum corrosion depths allowed on the various components of the nose landing gear. When damage exceeds the limits specified in the SRM or the corrosion control section of the MIM, the affected part must be replaced if structural repair of the damage is not possible. Table 4-3.—Recommended Grit for Steel and Aluminum TYPE OF RECYCLING NON-RECYCLING METAL BLASTED GRIT SAE PRES GRIT SAE PRES MESH PSI MESH PSI Steel Angular silica 20/40 75 Silica sand 20/40 75 Sand Crushed garnet 20/40 75 Crushed garnet 20/40 75 Aluminum oxide 20/50 50 Aluminum Silica sand 20/40 75 Silica sand 20/40 75 Aluminum oxide 20/50 50 Crushed garnet 20/40 75 Crushed garnet 20/40 75 4-43

Figure 4-29.—Nose gear maximum corrosion depths. 4-44

Q74. Information regarding corrosion removal limitations can be found in what publications? CHEMICAL SURFACE TREATMENT LEARNING OBJECTIVE: Define the purpose for chemically preparing a surface for priming and painting. Chemical conversion coatings increase a surface’s resistance to corrosion and improve paint bonding on the surface. The metal to be treated must be cleaned to a water breakfree surface (fig. 4-30). Metal surfaces not free of water breaks must be recleaned with a solution of 1 part MIL-C-43616 or MIL-C-25769 aircraft cleaning compound to 16 parts of water, and then rinsed with water. Surfaces that have been waxed, particularly with silicone wax, may require special cleaning. After cleaning and removal of surface oxides, aluminum should be treated with MIL-C-81706 and magnesium with MIL-M-3171, type VI, chemical conversion coating material. 214.248 Figure 4-30.—Water break comparison. CAUTION Personnel must wear protective clothing, rubber gloves, and chemical goggles when using a solution of MIL-C-81706 and MIL- M-3171 or serious injury could result. Apply these chemical conversion coatings immediately after cleaning the surface to a water breakfree surface and while the surface is still wet. Apply these coatings by brush, nonatomizing spray, or sponge stick moistener. The sponge stick moistener is particularly useful for small areas. Soluble salt residues that remain on the surface after treatment accelerate corrosion and can cause blistering of paint finishes. Thus, complete rinsing with fresh water following the chemical treatment is very important. Flush the chemical with free-flowing water only. Allow the chemical conversion coated surface to dry (usually 30 minutes) before painting. Do NOT wipe the surface with a damp cloth or brush, as this will degrade or remove the chemical conversion coating. Chemical conversion coatings are often damaged during aircraft maintenance, or they may be contaminated by grease, oil, or other foreign matter. Therefore, the treated surface should be painted soon after treating to obtain the best results. CHEMICAL CONVERSION OF ALUMINUM ALLOYS The procedure to be used for the chemical conversion of aluminum alloys is as follows: Apply the conversion coating material, MIL-C-81706 (Form V [powdered] is preferred, Form III [premixed] is an alternate), until you obtain a golden iridescent color. Immediately rinse the chemical from the surface with large amounts of fresh water when you obtain the proper color conversion. This rinsing stops the chemical action and minimizes solution entrapment. Failure to rinse may accelerate corrosion and reduce paint bonding. If a long period of contact before rinsing is allowed, a powdery, coated surface may be the result. CHEMICAL CONVERSION OF MAGNESIUM ALLOYS The procedure for the chemical conversion of magnesium alloys is as follows: Apply the conversion 4-45

coating material MIL-M-3171 until you obtain a greenish-brown or brass-colored yellow color. For a proper conversion coating, keep the surface wet with the specified solution until you obtain the desired color. Rinse with fresh water. Remove any excess conversion coating solution that collects into pools within the aircraft. Some magnesium parts in later model aircraft were originally protected by a proprietary (held under patent) electrolytic process. One process is identified by the brown to mottled gray appearance of the unpainted surface. Another process will appear as a green to grayish-green color. These coatings are thicker than those applied by the immersion or brush method, such as MIL-M-3171. The electrolytic finish cannot be restored in the field. Therefore, when failure of the coating occurs, you should remove corrosion and touch up the bare magnesium with MIL-M-3171 chemical treatment solution. You should minimize removal of the electrolytic coatings, as they afford greater protection than the replacement coatings. Q75. What is the purpose for chemically treating a surface for painting? Q76. When failure of the coating occurs, you should remove corrosion and touch up the bare magnesium with what chemical treatment solution? AIRCRAFT PAINTING AND COMPONENT TOUCH-UP LEARNING OBJECTIVE: Identify the materials used and procedures for painting aircraft. The amount of paint touch-up done at organizational- and intermediate-level maintenance varies widely. The amount depends upon the activity involved, the availability of facilities, and the area of operations. The primary objective of any paint finish is the protection of the exposed surface against decay. There are secondary reasons for particular paint schemes. Glare is reduced by nonspecular (not mirrorlike) coatings. White or light-colored, high-gloss finishes reduce heat absorption. Camouflage, high visibility, or special identification marking requirements are met by various paint schemes. REPAINTING SHOULD NOT BE DONE FOR APPEARANCE SAKE ONLY. A faded or stained but well-bonded paint finish is better than a fresh touch-up treatment applied over dirt, corrosion products, or other contaminants. Complete refinishing (particularly under field conditions) should be restricted to those areas where existing paint finishes have degraded until they fail to perform their protective function. However, the organizational and intermediate levels of maintenance should evaluate maintenance and repair of paint finishes. This should be done at the time of aircraft receipt and through constant surveillance and maintenance of finishes during an aircraft’s service tour. Maintenance also should make final recommendations for refinishing an aircraft when the aircraft is scheduled for standard depot-level maintenance (SDLM). General safety precautions should be followed when you paint and when you use special types of paints. These precautions include the following: No eating, drinking, or smoking is allowed in areas where paint or solvent is being used. Prolonged breathing of vapors from organic solvent is dangerous. Prolonged skin contact with organic solvents or materials containing organic solvents can have a toxic effect on the affected skin area. PAINT REMOVAL Paint removal operations at the organizational and intermediate levels of maintenance are usually confined to small areas, or possibly a whole panel. In all cases, the procedures outlined in the MIM that applies should be observed. General stripping procedures are contained in NAVAIR 01-1A-509. Materials All paint removers are toxic and caustic; therefore, both personnel and material safety precautions must be observed in their use. Personnel should wear eye protection, gloves, and a rubber apron. Paint remover, specification MIL-R-81294, is an epoxy paint remover for use in the field. This remover will strip acrylic and epoxy finishes. Acrylic windows, plastic surfaces, and rubber products are damaged by this material. This material should not be stocked in large quantities as it ages rapidly, degrading the results of stripping action. This paint remover must NOT be used to remove paint from composite materials. 4-46

Procedures and Precautions The stripping procedures described below are general in nature. When stripping any aircraft surface, you should consult the applicable MIM for the specific procedures to be used. Stripping should be accomplished outside whenever possible. If you must strip aircraft surfaces in a hangar or other enclosure, you should make sure you have adequate ventilation. You should adhere to the following general procedures and precautions during stripping operations: CAUTION Before cleaning and stripping, make sure that the aircraft is properly grounded. This will dissipate any static electricity produced by the cleaning and stripping operations. Where the paint remover may contact adhesives, mask all seals, joints, skin laps, and bonded joints by using the approved tapes and papers. Apply the stripper liberally. Completely cover the surface with a thick layer of stripper with a paint or acid brush. The stripper should not be spread in a thin coat like paint because it will not loosen paint sufficiently for removal, and the remover may dry on the surface of the metal. This would require it to be reapplied. Allow the stripper to remain on the surface long enough for it to wrinkle and lift the paint. This may be from 10 to 40 minutes, depending upon temperature, humidity, and the condition of the paint coat being removed. Reapply paint remover as necessary in the areas where paint remains tight or where the material has dried. Remove loosened paint and residual paint remover by washing and scrubbing the surface with fresh water, fiber scrapers, bristle brushes, and rags. If water spray is available, you should use a low-to-medium pressure stream of water. Apply it directly to the surface while scrubbing the surface. After a thorough cleaning, you should remove masking materials and clean any residual paint from the surface. Rinse with water and clean the area with aircraft cleaning compound (1 part MIL-C-85570 to 9 parts water) to remove paint remover residue. Flap Brush Paint can be mechanically removed with a flap brush. The brush consists of many nonwoven, nonmetallic, nylon flaps bonded to a fiber core. The brush assembly (fig. 4-31) is made up of a flap brush, flanges, and mandrel. Use a NO LOAD 3200 rpm pneumatic drill motor to power the brush. Do not use a flap brush that is worn down to within 2 inches from the center of the hub. Continued use beyond this limit may cause gouging due to loss of flexibility of the fiber. When you use a flap brush, apply minimum pressure to remove the most paint and the least metal. Excessive pressure will cause some paints to melt, gum up, and streak around the area being worked. For safe and efficient operation, the direction of rotation is indicated by an arrow imprinted on the inside of the core. Wear eye protection when operating a flap brush, and consult your maintenance instruction manuals for limitations on corrosion removal. Q77. What is the primary purpose of any paint finish? Q78. When using paint removers, you should wear what type of protective clothing? Q79. What safety precaution must be taken before cleaning and stripping old finishes on aircraft? Q80. What type of motor should you use to power a flap brush? Figure 4-31.—Flap brush and mandrel. 4-47

SURFACE PREPARATION The effectiveness of any paint finish and its bond to the surface depends upon the careful preparation of the damaged surface before touch-up. The touch-up paint should overlap onto the existing good paint finish. The touch-up materials will not bond to glossy finishes, so the finishes must be prepared. Also, any edges of the existing film will show through the overlap unless they are smoothed out. To break the gloss of existing finishes and to feather (smooth out) the edges for overlap, you should scuff sand by using 240 or 320 grit aluminum oxide cloth. After sanding, use a water rinse to remove the abrasive residues. You should remove any loosened seam sealants in the area to be touched up and replace them as necessary. Also, resecure any loose rubber seals by using the type of adhesive specified in the applicable MIM. Then outline the area to be painted with tape and masking paper, as shown in figure 4-32. This protects the adjoining surfaces from overspraying and unwanted paint buildup. TOUCH-UP PROCEDURES A standardized paint system for O- and I-level painting and paint touch-up is presented in NAVAIR 01-1A-509. Standardized exterior paint touch-up systems for organizational and intermediate levels of maintenance consist of an epoxy primer (MIL-P-23377, type I or type II, as applicable) overcoated with aliphatic polyurethane (MIL-C-85285). Paint systems are identified by a decal or stencil located on the right side of the aft fuselage. Standardized interior paint touch-up systems for O- and I-level maintenance consist of zinc chromate primer (TT-P-1757). Paint materials that are within their original shelf life or within an extended shelf life are preferred. However, if materials are beyond shelf life date, test them by using a small sample of scrap aluminum. The following paragraphs furnish the basic information for identifying and applying the standard touch-up paint systems. Complete information on the types and applications of aircraft paint systems is contained in NAVAIR 01-1A-509. Figure 4-32.—Masking before paint touch-up. Epoxy-Polyamide Primer (MIL-P-23377) The epoxy-polyamide primer is supplied as a two-part kit. Each part must be stirred or shaken thoroughly and separately before they are mixed together. One part contains the pigment particles in an epoxy vehicle. The other part is composed of a clear polyamide solution that functions as a hardener for the epoxy solution. This primer is supplied by various manufacturers. You should mix only as much primer as needed. The storage life of the primer is limited after it is mixed to the amount that can be used in 4 hours. Refer to NAVAIR 01-1A-509 for specifics on mixing these two components. Zinc Chromate Primer Zinc chromate primer (TT-P-1757) is a general-purpose, interior, protective coating for metal surfaces. Depending upon the location, zinc chromate primer may or may not require a topcoat. Zinc chromate primer is easy to apply or remove as it is a single component. There is no thinning required for brush or roller application however, for spray application, thin this primer with MIL-T-81772. Do not use zinc chromate primer on exterior aircraft surfaces, including wheel wells and wing butts, and in areas that are exposed to temperatures exceeding 175°F (79.4°C). Polyurethane Finish Systems You must have a physical examination before you can work with polyurethane coatings. Also, you must 4-48

have periodic physicals during the time you are working with these coatings. There are two types of polyurethane systems used on naval aircraft-the aliphatic type (used in MIL-C-85285 and TT-P-2756 polyurethane paints) and the aromatic type (used in polyurethane, rain erosion-resistant coatings, MIL-C-85322). These materials present no special hazard to health when cured (dried), but they require special precautions during preparation, application, and curing due to the isocyanate vapors produced. The isocyanates vapors can produce significant irritation to the skin, eyes, and respiratory tract even in very small concentrations. They also may induce allergic sensitization of personnel exposed to their vapors and mists produced during spray applications. Aliphatic polyurethane. MIL-C-85285, is the standard, general-purpose, exterior, protective coating for aircraft surfaces. The polyurethane finish comes in kits that consist of a two-component material resin and a catalyst. The touch-up kits are prethinned and ready for use when they are mixed according to the instructions in the kit. Use aliphatic polyurethane over epoxy polyamide primer and for touch-up and insignia markings over polyurethane paint systems only. Acrylic Lacquer Acrylic lacquer (gloss and camouflage) MIL-L-81352 is the preferred topcoat material for aircraft markings that identify the reporting custodian and for propeller safety stripes. Enamel Finishes Most enamel finishes used on aircraft surfaces are baked finishes that cannot be touched up with the same materials in the field. Minor damage to conventional enamel finishes ordinarily used on engine housings is repaired by touching up with epoxy topcoat material or air-drying enamel. Elastomeric Rain Erosion-Resistant Coating (MIL-C-85322) Elastomeric coatings are used as a coating system to protect exterior laminated plastic parts of high-speed aircraft, missiles, and helicopter rotary blades from rain erosion in flight. They offer good resistance to weather and aromatic fuels in addition to rain erosion. Excellent bonding is obtained after a 7-day drying period. Repair to these coatings in the field is not practical due to this long curing time. Kits are available for repair of coatings where limited touch-up is required. These kits contain a primer, neoprene topcoat, and antistatic coating. If the radome or leading edge coatings are in bad condition, they should be stripped completely and recoated with epoxy primer and acrylic topcoat as a temporary measure. If schedules and conditions permit adequate curing of elastomeric coatings, the original coatings may be replaced. The repair kits are normally bought as an open purchase to ensure that fresh materials are available. Since heat accelerates aging, repair kits should be stored in a cool place or refrigerated. Stripping of fiber glass surfaces should be done according to current maintenance instructions. Elastomeric coatings are toxic and flammable, and must be used with care. PAINTING EQUIPMENT (SPRAY GUNS) The spray gun atomizes the material to be sprayed, and the operator directs and controls the spray pattern through manipulation and minor adjustments of the spray gun. Spray guns are usually classed as either a suction-feed or pressure-feed type. The type of spray gun can be determined by two methods-by the type of container used to hold the paint material and by the method in which the paint is drawn through the air cap assembly. For information on the types of spray guns, refer to NAVAIR 01-1A-509. Suction-Feed Type The suction-feed spray gun is designed for small jobs. The container for the paint is connected to the spray gun by a quick-disconnect fitting, as shown in figure 4-33. The capacity of this container is approximately 1 quart. The fluid tip of this spray gun protrudes through the air cap, as shown in figure 4-34. The air pressure rushing by the fluid tip causes a low-pressure area in front of the tip. This causes paint to be drawn up through the fluid tip, where it is atomized outside the cap by the air pressure. Pressure-Feed Type The pressure-feed spray gun is designed for use on large jobs where a large amount of spray material is to be used. With this type of spray gun, the material is supplied to the gun through a hose from a pressurized tank. This spray gun produces a high volume of spray material metered at a low air pressure. This type of 4-49

SEALANTS Figure 4-33.—Suction-feed type of spray gun. Figure 4-34.—Suction and pressure fluid tips and air caps. spray equipment eliminates evaporation of the volatile substances of the mixture before they strike the surface because the paint and air are mixed internally. Thus, a wetter coating is applied. CAUTION Many of the sealants discussed in this sec- tion may be flammable or produce toxic vapors. When materials designated as flammable are used, ail sources of ignition must be at least 50 feet away from the work location. Toxic vapors are produced by the evaporation of solvents or the chemical reaction that takes place in the curing sealants. When sealants are used in a confined space, such as a fuel cell, fuselage, wing section, or table or bench operation, adequate local exhaust ventilation must be used. This will reduce the vapors below the maximum allowable concentration and keep them at that level until repairs have been completed. Personnel must NOT eat or smoke when they work with sealants. Sealants are used to prevent the movement of liquid or gas from one point to another. They are used in an aircraft to maintain pressurization in cabin areas, to retain fuel in storage areas, to achieve exterior surface aerodynamic smoothness, and to weatherproof the airframe. Sealants are used in general repair work in the field and for maintenance and restoration of seam integrity in critical areas if structural damage or the use of paint removers has loosened existing sealants. Conditions surrounding the requirements for use of sealants govern the type of sealants to be used. Some sealants are exposed to extremely high or low temperatures. Other sealants are in contact with fuels, lubricants, and so forth. Therefore, sealants are supplied in different consistencies and rates of cure. The basic types of sealants are classified in three general categories-pliable sealants, drying sealants, and curing sealants. Pliable sealants are called “one-part” sealants and are ready for use as packaged. They are solids and change little, if any, during or after application. Solvent is not used in this type of sealant. Therefore, drying is not necessary; and except for normal aging, they remain virtually the same as when first packaged, neither hardening nor shrinking. They bond well to metal, glass, and plastic surfaces. Pliable sealants are used around high-usage access panels and doors, and 4-50

in areas where pressurized cavities must be maintained. Drying sealants set and cure by evaporation of the solvent. The solvents in these sealants provide the desired consistency for application. Consistency or hardness may change when this type of sealant dries, depending upon the amount of solvent it contains. Shrinkage is a consideration when these sealants are used. Shrinkage occurs upon drying. The degree of shrinkage depends on the proportion of solvents. Catalyst-cured sealants have advantages over drying sealants. They are transformed from a fluid or semifluid state into a solid mass by chemical reaction of physical change rather than by evaporation of a solvent. A chemical catalyst of accelerator is added and thoroughly mixed just before sealant applications. Heat may or may not be used to speed up the curing process. When a catalyst is used, accurate proportioning and thorough mixing of the two components are very important to assure a complete and even cure. Application of Sealants Application of sealants varies according to time element, tools required, and the method of application. However, the following restrictions apply to all sealant applications: Sealants should be used within the approximate application time limits specified by the sealant manufacturer. Sealants should not be applied to metal that is colder than 70°F. Better bonding is obtained and the applied sealant will have less tendency to flow out of place while curing if the metal is warmed to a temperature of 90°F to 100°F before the sealant is applied. Sealants should be discarded immediately when they become too stiff to apply or work readily. Stiff or partially cured sealants do not wet the surface to which they are applied as well as fresh material. This causes uneven bonding. Sealants should not be used for close-fitting (faying) surface applications unless they have just been removed from refrigerated storage or freshly mixed. Brushes, dipping, injection guns, spatulas, and spray guns are the methods used to apply sealants. Figure 4-35 shows (black areas) where sealant is applied to protect some of the most corrosion-prone areas on an F-14 aircraft. The sealant is applied by using the spray, spatula, and brush methods. Sealant MIL-S-81733, type III, is the sealant used most extensively for spray application. If type III sealant cannot be procured, sealant MIL-S-8802, class A, may be used by thinning it to a sprayable consistency by the addition of the correct solvent. When an aircraft is pressure sealed, the sealing materials should be applied as a continuous bead, film, or fillet over the sealed area. Air bubbles, voids, metal chips, or oily contamination prevent an effective seal. Therefore, the success of the sealing operation depends upon the cleanliness of the area and the careful application of the sealant materials. There are various methods of pressure-sealing joints and seams in aircraft. The applicable SRM will specify the method to be used in each application. The sealing of a faying surface is done by brush. The contacting surfaces are coated with the specified sealant. Application of the sealant should be made immediately before the parts are fastened together. Careful planning of work and equipment are necessary so faying surface seals on large assemblies may be closed within the application time limit of the sealant. Once the sealant has been applied, the parts must be joined, the bolts torqued, and the rivets driven all within the application time limit. When insulating tape has been installed between the faying surfaces to prevent contact of dissimilar metals, pressure sealing should be done by fillet sealing. In fillet sealing, the sealant is spread along the seam with a sealant injection gun in about 3-foot increments. Before proceeding to the next increment, the applied portion of the fillet is worked in with a sealant spatula or tool (fig. 4-36). This working of the sealant is done to till in all voids in the seam and to eliminate most air bubbles. The care used in working out the air bubbles determines the leakfree service life of the sealant. After the sealant has cured to a tackfree condition, the fillet should be inspected for remaining air bubbles. These air bubbles should be opened and filled with sealant. When a heavy fillet is required, the fillet should be applied in layers. The top layer should fair with the metal. Injection sealing is the pressure filling of openings or voids with a sealant injection gun. The sealant is forced into the opening until it emerges from the opposite side. Voids and cavities are filled by starting with the nozzle of the sealant injection gun at the bottom of the space and tilling as the nozzle is 4-51

Figure 4-35.—Sealant applied to aircraft exterior surfaces. 4-52

Figure 4-36.—Applying sealant. withdrawn. An example of injection sealing is the caulking of a leaking fuel cell. Fasteners, such as rivets, Rivnuts, screws, and small bolts, should have a brush coat of sealant over the protruding portion on the pressure side. Washers should have a brush coat of sealant on both sides. Split-type grommets should have sealant brushed into the split before installation. After installation, fillets should be applied to both the base of the grommet and the protruding tube on the pressure side. Sealing Compound (MIL-S-8802). MIL-S-8802 is a temperature-resistant (-65°F to +250°F), two- component, synthetic rubber compound used for sealing and repairing fuel tanks and fuel-cell cavities. It is produced in three classifications. Class Use A For brushing application B For extrusion gun and spatula application C For faying surface sealing Sealing Compound (MIL-S-81733). MIL-S-81733 is an accelerated, room-temperature curing, synthetic rubber compound. It is used in sealing metal components on weapons and aircraft systems for protection against corrosion. This sealant contains a corrosion inhibitor. Figure 4-37 shows MIL-S-81733 sealing compound used to seal an antenna. It comes in four types. Type Applied by Maximum application time in hours I Brush 1/2 Dip 2 II Extrusion 1/2 Gun 2 Spatula 4 III Spray gun 1 IV Brush or Spatula 12 to 48 Figure 4-37.—Typical fleet antenna sealing application. 4-53

Sealing Compound (MIL-S-8516). MIL-S-8516 is an accelerated, synthetic, rubber sealing compound used for sealing low-voltage electrical connectors, wiring. and other electrical equipment against moisture and corrosion where temperatures do not exceed 200°F. This sealant has very good resistance to fuels, oils, grease, water, and humidity. However, it is NOT authorized for use in engine bays, keel areas, or areas adjacent to bleed-air ducts. It is manufactured in kit form and comes in sizes from 2.5 ounces to 1 quart. MIL-S-8516 is available in three classes with different curing times. Class Curing time in hours 1 24 2 48 3 72 Silicone Rubber Sealant (MIL-S-23586). Room temperature vulcanizing (RTV), silicone rubber sealant is used for sealing small electrical connectors and electrical components that are located in areas where the temperatures are between 200°F and 450°F. This sealant has good resistance to weathering, moisture, and withstands ozone. RTV silicone rubber sealant is available in two types, both used for the same purposes. The two types are type II, class 2, grade A, and type 1, class 1, grade B- 1. Type II, class 2, grade A contains cure volatiles and should be used only in well-ventilated areas. Adhesive Silicon Sealant (MIL-A-46146). Also known as 3145 RTV. A noncorrosive sealant for use on sensitive metals and avionics equipment in areas that are exposed to temperatures between 250°F and 350°F. This sealant comes in 3-, 8-, and 12-ounce tubes. CAUTION Many RTV silicone sealants contain an acetic acid curing agent. These sealants, when in contact with metal, cause rapid corrosion. RTV sealants that contain acetic acid are NOT authorized for use on electronic or elec- trical circuits. They may be identified by the emission of a vinegar odor while in a liquid or curing state. Q81. Complete information on the types and applications of aircraft paint systems is contained in what publication? Q82. After it is mixed, the storage life of epoxy-polyamide primer is limited to the amount that can be used in how many hours? Q83. What is the standard, general-purpose, exterior protective coating for aircraft surfaces? Q84. What are the two classes of spray guns? Q85. When flammable materials are used, all sources of ignition must be at least how far away from the work location? SUMMARY This chapter identifies the manuals and procedures used to detect and combat corrosion on naval aircraft and support equipment. It identifies the types and causes of corrosion. Familiarize yourself with types and uses of cleaning materials and the procedures and materials for preservation and depreservation. This is vital information. 4-54

ANSWERS TO REVIEW QUESTIONS A1. A2. A3. A4. A5. A6. A 7. A8. A9. A10. A11. A12. A13. A14. A15. A16. A17. A18. A19. A20. A21. They must be kept in specially marked containers. A22. In a separate building or-flammable liquids storeroom. A23. It is applied by spraying, dipping, brushing, or wiping. A24. 1,1,1-trichloroethane. Corrosion reduces the strength and changes the mechanical characteristics of the material. Corrosion control. Weight-to-strength ratio. Metal corrosion, Protection from corrosive environments. Electron flow is established from the cathode to the anode. They speed the corrosion process. Thick sections are more likely to have variations in their composition, particularly if heat-treated during fabrication. Moisture is the single largest contributor to avionics corrosion. NAVAIR 01-1A-509. NAVAIR 16-1-540 provides information on cleaning and corrosion prevention and control of avionics equipment. NAVAIR 15-01-500, Preservation Of Naval Aircraft. General uses for cements, sealants, and coatings. A period of intensive care should follow the deployment cycle to bring the aircraft back up to standard. A good corrosion prevention program. Every 14 days. a. Aircraft is exposed to corrosive fire-extinguishing materials. b. Spilled electrolyte and corrosive deposits are found around battery terminals and battery area. c. The aircraft has been exposed to significant amounts of salt water. d. Salt deposits, relief tube waste, or other contaminants are apparent. e. Fungus growth is apparent. f. Chemical, biological, or radiological contaminants are detected. They must be cleaned or wiped down. Flammability and toxicity Inhaling toxic vapors can seriously affect the brain and central nervous system. 4-55

A25. A26. A27. A28. A29. A30. A31. A32. A33. A34. A35 A36. A37 A38. A39. A40. A41. A42. A43. A44. A45. A46. A47. A48. A49. a. Apply by wiping or scrubbing the affected area with an acid brush or toothbrush. b. Air dry or oven dry as applicable. c. Do not use on acrylic plastics or acrylic conformal coatings. d. Do not use on unsealed aluminum electrolytic capacitors. Damage may result to end caps and cause leakage. Silicon carbide paper because it is sharp and the individual grains can penetrate steel surfaces. Because it conforms to the surface, the applicator allows easier application of a constant scrubbing pressure on curved skin panels. MIL-C-85570. Select the proper cleaning agent for the method of cleaning chosen. Upward and outward. Dry-cleaning solvent. It is not oxygen compatible and will cause explosion or fire. A polyethylene sheet, polyethylene-coated cloth, or metal foil barrier materials. The maintenance instructions manual (MIM). NAVAIR 01-1A-509. Level I—Short term, up to 60 days. Level II—60 days to 1 year. Level III—Long term, 1 to 8 years. Level I preservation. All three. Grades I, IL and IV. Antifriction bearings, shock-strut pistons, and other bright metal surfaces. It is used when a water-displacing, low temperature, lubricating oil is required. Type III. Level I. Ground Support Equipment Cleaning and Corrosion Control, NAVAIR 17-1-125. Silicone sealant MIL-A-46146, type I, and polysulfide sealant MIL-S-81733 or MIL-S-8802. Uniform or direct surface attack Aluminum and magnesium alloys. White or gray powdery deposit. Avoid the creation of crevices during repair work. Intergranular corrosion is an attack on the grain boundaries of alloys under specific conditions. 4-56

A50. It is usually the result of faulty design or improper maintenance practices. A51. Stress induced by press-and-shrink fits and those in rivets and bolts. A52. Fatigue corrosion is caused by the combined effect of corrosion and stress applied in cycles to a component. A53. A slight vibration, friction, or slippage between two contacting surfaces that are under stress or heavy load. A54. A55. A56. A57 A58. A59. A60. A61. A62. A63. A64. Steel, aluminum, and magnesium. Applicable periodic maintenance information cards (PMICs). A cathode, an anode, and an electrolyte. Black paint to prevent glare. Daily. NAVAIR 01-1A-509. Iron rust. Clad, anodized, and exfoliated. Hand polish the corroded areas with MIL-P-6888 metal polish. Nonclad aluminum alloys. Aluminum wool or fiber bristle brushes. A65. An aeronautical engineer. A66. Structural repair manuals for the specific aircraft model. A67. Contacts, springs, connectors, printed circuit board runs, and wires. A68. In the engine exhaust areas. A69. A70. A71. A72. A73. A74. A75. A76 A77. A78. A79. A80. Conduct an inspection and evaluation of the suspected area, Extensive hand sanding or light mechanical sanding. VACU-Blast dry honing portable machine. Abrasive or grit blasting. Sodium Nitrite MIL-S-24521. The applicable aircraft Structural Repair Manual (SRM) or the "Corrosion" section of the Maintenance Instruction Manual (MIM) Chemical conversion coatings increase a surfaces resistance to corrosion and improve paint bonding to the surface. MIL-M-3171. The protection of the exposed surfaces against decay. You should wear eye protection, gloves, and a rubber apron. Ensure the aircraft is properly grounded. Use a NO LOAD 3200 rpm pneumatic drill motor. 4-57

A81. NAVAIR 01-1A-509. A82. 4 hours. A83. Aliphatic polyurethane, MIL-C-85285. A84. Suction feed and pressure-feed spray guns. A85. 50 feet. 4-58

CHAPTER 5 LINE OPERATIONS AND SPECIAL PROGRAMS One of the busiest, most important and dangerous divisions in a squadron is the line division. Upon reporting to a squadron, no matter your rate or paygrade, you may be assigned to the line division. As an Airman, or third class petty officer, you may become a plane captain. A plane captain has many responsibilities in flight operations and in the day-to-day maintenance of modern aircraft. As a more senior petty officer or a Chief, you may be assigned as the LPO or Branch Chief. It is important for you to know how the line division operates and the safety factors involved with line operations. This chapter briefly outlines some of these crucial factors. ORGANIZATION LEARNING OBJECTIVE: Identify the organization of the line division and define the responsibilities and qualifications of a plane captain. The following text discusses the organization of the line division. Knowledge about the line organization is important because it will help you perform your duties. The line division is a division within the maintenance department. Figure 5-1 shows how the line division fits within the maintenance department. The aircraft maintenance officer is the department Figure 5-1.—Navy O-level maintenance department organization. 5-1

head, and each division has a division officer. The size of the squadron will determine if you have a branch officer. The line chief petty officer (CPO) is the division CPO. Normally, you will work directly for the line petty officer or a shift supervisor. There are three branches (two afloat) within the line division. The following paragraphs discuss these branches. TROUBLESHOOTER BRANCH The troubleshooter branch provides a rapid means of troubleshooting and repairing discrepancies discovered on the flight line. Also, troubleshooters are technical advisors to the plane captains. Troubleshooters may be permanently assigned to the line division or they may be temporarily assigned from other work centers on a daily or hourly basis. They must be knowledgeable in line operations, flight line safety, and aircraft systems. SUPPORT EQUIPMENT BRANCH Only shore-based squadrons have support equipment (SE) branches. Lack of space aboard ship makes it impossible to store SE; therefore, an SE branch is not possible. Normally, your squadron will check out SE needed on the line. When SE is no longer needed, it is returned to the aircraft intermediate maintenance department (AIMD). The SE branch is responsible for the SE used by the squadron. This responsibility includes the daily/operational inspections performed on the equipment, and in some cases, minor maintenance. Refer to local procedures when you work with SE. PLANE CAPTAIN BRANCH The plane captain branch of the line division is made up of qualified plane captains and trainees (persons in training to become qualified plane captains). This branch normally has between 75 and 95 percent of the total personnel assigned to the line division. The branch does routine maintenance (daily/turnaround inspections and cleaning) and other organizational maintenance assigned by maintenance control. You cannot become a qualified plane captain automatically. You must work long hours and demonstrate that you know the aircraft and its operation (orally and in writing). After demonstrating your ability. you will be designated, in writing, as a plane captain by the commanding officer. The following paragraphs discuss the duties and qualifications of a plane captain. Plane Captain Duties Because naval aircraft are very complex, the plane captain does not have in-depth knowledge of all the systems contained in the aircraft. Therefore, technicians other than the plane captain must perform those portions of the daily and turnaround/preflight inspections that are beyond the technical qualifications of the plane captain. This assistance does not relieve the plane captain of their overall responsibility for the aircraft. The following is a list of the minimum duties of a plane captain: Perform daily, preflight, postflight, and turnaround inspections with assisting personnel, and assist others in performing O-level maintenance. Assists the pilot in flight preparation and advises the pilot of the material condition of the aircraft. Responsible for the cleanliness and prevention of corrosion on the aircraft by pursuing an effective and continual preventive maintenance program. Perform the work required and assist on phase, special, and conditional inspections within the rating specialty as required by maintenance requirements cards (MRCs). Plane Captain Qualifications Assignment as a plane captain carries a high degree of responsibility. The selection of the right person to be a plane captain is important. Regardless of rating, this person must possess the mechanical aptitude, personal integrity, and motivation necessary for the job. These qualities help to ensure that the aircraft is properly inspected and serviced before each flight. A broad screening of available personnel in the aviation ratings and comprehensive formal and on-the-job (OJT) training programs ensure that only the most qualified individuals are designated as plane captains. The following is a list of qualifications for plane captains. Possess the qualities of personal integrity, maturity, judgement, and aptitude. Demonstrate knowledge of the particular type of aircraft and its systems, including its cockpit, ejection seats, and controls. Demonstrate knowledge of the ordnance or armament equipment installed in or on the aircraft, and ensure that the armament, ejection seat, and other cartridge-activated devices are in a safe and ready condition during daily, preflight, postflight, and turnaround inspections. 5-2

Demonstrate knowledge of and compliance with fueling and defueling procedures, and follow the applicable safety instructions. Demonstrate ability to use the methods of aircraft security required for various weather conditions and shipboard operations. Give particular attention to the security of control surfaces and the correct points for attaching tie-downs. Demonstrate, in writing and by practical application, knowledge of the procedures for riding brakes and any peculiarities of the braking system of the assigned aircraft, as well as a knowledge of the standard signals (including those contained in NATOPS, both hand and wand) used for controlling aircraft on the ground or flight deck. Q1. To what department is the line division assigned? Q2. What branch is responsible for the support equipment used by the squadron? Q3. In most squadrons, 75 to 95% of the personnel assigned to the line division are assigned to what branch? Q4. After demonstrating your abilities as a plane captain, who has the final authority to designate you a plane captain? AIRCRAFT SERVICING LEARNING OBJECTIVE: Recognize safety procedures and the proper equipment used in servicing aircraft. Aircraft servicing is an important part of daily and turnaround inspections that plane captains perform, Even when plane captains do not personally perform the servicing, they must still ensure that it is done correctly. A typical daily/turnaround record is shown in figure 5-2. However, the aircraft may require servicing at more frequent intervals. Daily and turnaround inspections are covered later in this chapter. The servicing of an aircraft includes replenishing fuel, oil, hydraulic fluid, and other consumable materials. Also, the tires are checked for proper inflation, struts for proper extension, and the various air storage units for proper pressure. GENERAL SAFETY PRACTICES This section lists some general safety practices that are important in day to day maintenance operations. 5-3 Fire Hazards Smoking is not permitted around the aircraft during fueling. Also, smoking or naked lights (such as oil lanterns, candles, matches, exposed electric switches, slip rings or commutators, dynamos or motors, any spark-producing electrical equipment, or any burning material) are not permitted within 100 feet of an aircraft that is being refueled or the fuel storage tanks. No lights other than approved explosionproof lights are permitted within 50 feet of refueling operations. No light of any sort may be placed where it can come in contact with spilled fuel. Warning signs should be posted as a precautionary measure. All accidental spillage of aircraft fuels or other combustible liquids must be contained and removed immediately with absorbent material, by covering with a foam blanket, or by neutralizing by other means to prevent ignition. Notify the proper fire authorities anytime a large amount of aviation fuel is spilled. Nonspark tools must be used when work is done on any part of a system or unit that is designed for storing or handling combustible liquids. The use of leaky tanks or fuel lines is not permitted. Repairs must be made upon discovery. Always keep in mind the hazards involved. Aircraft should be fueled in a safe place. Shore-based aircraft may not be fueled or defueled in a hangar or other enclosed space except in an emergency. Aircraft should be free from fire hazards, have the engine switches in the OFF position, and have chocks placed under the wheels before fueling or defueling operations are begun. CAUTION You should guard against breathing hydro- carbon (fuel) vapors. They may cause sick- ness, or they may be fatal. Do not let fumes accumulate. Use adequate ventilating meas- ures. Also, avoid getting fuel on your clothes, skin, or eyes because of the high lead content. If your clothing becomes saturated with fuel, remove them as soon as possible. The parts of your body that are exposed to fuel should be washed thoroughly with soap and water. Clothing saturated with fuel creates a danger- ous fire hazard. Also, painful blisters similar to fire burns may be caused by direct contact of the skin with fuel. If fuel gets in your eyes, flush them with water and obtain medical at- tention.

Figure 5-2.—Preflight/Daily/Turnaround/Postflight Maintenance Record. Aircraft Walkways discussed in the following text and are shown in figure 5-3. NO STEP markings provide guidance on how to use walkways on aircraft wings and stabilizers as well as on the fuselage. These markings vary with different NO STEP markings on the wings form a boundary along leading and trailing edges. The area within the boundary is the walkway. Do not step on the wingtips models of aircraft; however, some general areas are or leading or trailing edges of the wings. 5-4

Figure 5-3.—Aircraft walkways and maintenance platform placement. 5-5

There are NO STEP markings on the leading and trailing edges of the horizontal stabilizer. These markings form a boundary around the surface on which maintenance personnel must not step or kneel upon unless they cover it with an approved nonabrasive surface mat. The mat distributes the load over a greater area. Stepping or kneeling on the unprotected horizontal stabilizer causes localized stressed areas that could result in structural damage to the surface. CAUTION Do not step or kneel on the overwing fair- ings. There are four NO STEP areas on the fuselage. These areas are aft center body, the upper speed brake, the area directly aft of overwing fairings, and the area directly behind the canopy. The NO STEP markings on the upper speed brake, aft center body, and the area directly aft of the over-wing fairing form a boundary around each of these surfaces on which maintenance personnel should not step. Maintenance Platform Placement The placement of maintenance platforms about an aircraft is shown in figure 5-3. Use the B-4 and B-5A adjustable maintenance platforms to gain access to the top of the aircraft. Then use aircraft walkways to move to the maintenance area. NOTE: The B-1 stand may be used as an alternate for the B-5A stand. FUEL REPLENISHMENT 5-6 Q5. Smoking and naked lights are not permitted within how many feet of a fueling operation? Q6. What type tools must be used when work is being performed on a system or unit that is designed for storing or handling combustible liquids. Q7. What are the four NO STEP areas on the fuselage? Aviation fuel is a highly volatile liquid that gives off a vapor. The vapor can be ignited by static sparks from tools, hot exhaust pipes, lighted cigarettes, and electrical devices. Thus, you must follow all fire precautions during the fueling process. When an aircraft is to be fueled by a truck, do not locate the aircraft near possible sources of ignition, such as grinding, drilling, or welding operations. When possible, refueling an aircraft from a truck should be carried out 50 feet from any other aircraft or structure and 75 feet from any operating radar set. You should consider wind direction so fuel vapors will not be carried toward a source of ignition. The tank truck should be driven to a point as far from the aircraft as the length of hose permits, but never within 10 feet of the aircraft, and preferably to the windward (upwind) side of the aircraft. The truck must be parked parallel to or heading away from the wing, or in such a position that it can be driven away quickly in case there is a fire. As soon as the fueling operation has been completed, the truck should be driven away from the vicinity of the aircraft. Refueling crews consist of a minimum of three people. One person stands with the fire-fighting equipment. A second person stays with the truck. The third person handles the fuel hose at the aircraft and fills the tanks. A member of the refueling crew makes sure that both the aircraft and truck are properly grounded. This prevents sparks from static electricity. Before starting fueling operations, the plane captain should check to see that all radio equipment and unnecessary electrical switches are turned off. Unless it is necessary to operate equipment involved with refueling, the crew should not connect outside electrical power to the aircraft. Before beginning refueling, the refueling crew should identify the aviation fuel. The type of fuel contained in the tank of a fuel truck is displayed across the side of each tank in 6-inch-high red lettering superimposed on 8-inch-high white reflective tape. As a plane captain or trainee who services an aircraft, you must know the various grades of fuel and the fuel requirements of the aircraft. This knowledge ensures that you will always use the correct fuel. Several systems are used to refuel naval aircraft. Some are refueled by the gravity system. Other aircraft may be refueled by either the gravity or pressure fueling system. Still other aircraft are fueled from a single point by the pressure fueling system. Gravity Fueling The hookup used for gravity fueling is shown in figure 5-4. The nozzle is grounded and then inserted into the cell filler neck. The tank is filled to the bottom of the filler port neck. The nozzle is always grounded

Figure 5-4.—Gravity fueling. before it is placed in the filler neck to prevent sparks caused by static electricity. Static electricity is built up by the fuel flowing through the hose. The nozzle should be supported while it is in the filler neck. This will prevent damage to the filler neck and, in the case of aircraft that use bladder-type fuel cells (cells made from a type of rubberized nylon cloth), prevent the possibility of damaging the cell with the end of the nozzle. Pressure Fueling Most naval aircraft are refueled by the pressure fueling system. This system gives the aircraft a faster operational turnaround time. Pressure fueling on an aircraft is usually done from a single point. Fuel from this point is supplied to the various wing and fuselage tanks. In some cases, the drop tanks and flight refueling package may be refueled from this point. The pressure-fueling station on the aircraft has a pressure-fueling and defueling receptacle and an electrical control panel (fig. 5-5). The pressure-fueling receptacle is standard on all aircraft that use the pressure-fueling method. However, the electrical panel and controls differ from one aircraft to another, depending upon the complexity of the fuel system. The general and servicing section of the applicable 5-7

Figure 5-5.—Pressure fueling. 5-8

maintenance instruction manual (MIM) contains illustrations of and instructions for the pressure fueling system. The pressure nozzle shown in figure 5-5 is permanently attached to the fuel hose. The pressure nozzle has a ground wire, which is used to drain off any static electricity that has built up in the nozzle. Once the nozzle is attached to the aircraft, however, it acts as a ground. When the pressure nozzle is connected to the aircraft, it opens a spring-loaded valve within the inlet to the fuel tanks. Aircraft that use this system have automatic equipment for shutting off the fuel flow when the tanks are full. Because the controls differ from one aircraft to another, you should always check the applicable MIM before pressure fueling an aircraft. The general procedures for pressure fueling are as follows: 1. Remove the pressure-fueling receptacle safety cap by turning it counterclockwise. Pull the pressure-fueling nozzle dust cover up and to one side of the outer shell. 2. Ground the nozzle by inserting the grounding plug into its receptacle on the aircraft. 3. Visually inspect aircraft adapter for any damage or significant wear. (A worn or broken adapter will allow the poppet valve to open and spray or spill fuel.) 4. Lift the nozzle by its handles into position. Engage the lower slot over the lower lug on the fueling receptacle. Tip the nozzle so that the upper slots engage the upper lugs. Press the nozzle in firmly so that all three nozzle lock keys are depressed. Lock the nozzle by rotating the lifting handles clockwise. 5. Set the refueling panel switches in the proper position, and apply electrical power to the aircraft. 6. Position the vent monitors, as necessary, according to the applicable MIM. NOTE: The vent monitors are assigned to the various fuel system vents to ensure that the aircraft’s fuel cells are venting properly. If the cells are not vented properly, there is the possibility that the cell will rupture and cause major structural damage. 7. When the nozzle is locked in place, the opening handle is free to turn when fueling is started. Turn the handle to the FULL OPEN position to start fueling. Rotating the opening handle more than 180° opens the poppet valve in the nozzle and locks it in the OPEN position. Position the appropriate switch on the fuel panel to the FUEL position. The fuel should shut off automatically when the ceils are full. CAUTION During pressure fueling, the fuel system should be inspected carefully for leakage. If any leaks are apparent, fueling should be stopped and corrective action taken. A fuel leak may cause injury or death to personnel. 8. When the fueling operation is complete, remove the pressure nozzle by rotating the lifting handles counterclockwise until the nozzle is unlocked from the fueling receptacle. Pull the dust cover up over the nozzle face immediately. Then replace the safety cap on the aircraft receptacle. You must take every safety precaution to make sure that no dirt or foreign matter enters the nozzle. The nozzle nose should be completely clean before it is connected to the aircraft. The dust cover must always be kept on the nozzle except when actually fueling an aircraft. The pressure fueling nozzle can be damaged by careless handling. Do not drop the nozzle or allow it to swing heavily against structures or equipment during handling. Never drag the nozzle on the deck. The operating action of the nozzle should never be forced. If the unit does not couple freely or open or close readily, locate and correct the misalignment or mechanical jam. Defueling Defueling may be necessary for many reasons, some of which are fuel cell repairs, removal of external fuel tanks, failure of fuel system components, and changing fuel loads. Aircraft that use pressure fueling are normally defueled from the pressure fueling adapter. This allows the entire system to be defueled from a single point. Some older aircraft have one or more defueling valves. Some residual fuel will often be left in the bottom of the fuel cell following defueling. Usually, residual fuel can be emptied or drained through the fuel cell water drain valves. A special adapter and appropriate container are used to catch the fuel. When external fuel tanks are defueled, 5-9

it maybe necessary to insert the defueling hose in the filler port. Normally, defueling operations are done outside the hangar and under controlled conditions. These conditions are specified in the general information and servicing volume of the applicable MIM. When it is absolutely necessary to defuel an aircraft in the hangar, the doors should be open to provide ventilation through the hangar. All shop doors leading into the hangar should be closed. No work should be done on or around the aircraft during the defueling operation. All sources of ignition should be prohibited in the area. Additional information on fueling and defueling aircraft can be found in the appropriate aircraft MIMs and the Aircraft Refueling NATOPS Manual, NAVAIR 00-80T-109. Q8. Why is wind direction an important consideration in fueling operations. Q9. Refueling crews consist of a minimum of how many people? Q10. Before beginning refueling operations, what is the first thing the refueling crew should do? Q11. What is the advantage of pressure fueling over gravity fueling? Q12. What manuals provide detailed fueling information for a specific aircraft? OIL REPLENISHMENT Aircraft engine oils are identified by either their military specification number (such as MIL-L-23699) or a four-digit number (such as 2085). The four-digit numbering system identifies the intended use and the viscosity of the oil. The first digit designates the intended use of the oil. The last three digits indicate the viscosity. For example, in the oil number 2085, the 2xxx series is for aircraft engine lubrication, and the 085 identifies the oil as having a viscosity rating of 85. Viscosity is defined as the internal fluid resistance to flow caused by molecular attraction. NOTE: Both the Navy and the Air Force use the Saybolt scale for determining viscosity. Saybolt viscosity numbers should not be confused with Society of Automotive Engineers (SAE) numbers that you see on automotive oil containers. The synthetic oils used in most turbojet engines are referred to by their military specification number, such as MIL-L-23699. Some aircraft engines use a combination of dry and wet sump-type lubrication systems. Others are lubricated entirely with a dry sump type. Wet sump engines store the lubricating oil in the engine proper (an automobile engine is an example of a wet sump engine), while dry sump engines use an external tank mounted on or near the engine. Oil in jet engines serves the two-fold purpose of lubricating and cooling. Servicing of the engine oil system is usually a simple task. It involves checking the tank for the proper oil level and bringing the oil level up to the required amount. On aircraft that have a dry sump system, servicing may consist of pumping uncontaminated oil directly into the supply tank. However, on some aircraft the tank is located in an inaccessible compartment, and a pressure tank is required to fill the oil tank. For specific servicing instructions of the engine oil system, refer to the applicable MIM. HYDRAULIC FLUID REPLENISHMENT Aircraft hydraulic fluids are identified by their military specification number. Hydraulic fluid, MIL-H-83282, is now being used in the hydraulic systems of all naval aircraft. This fluid is also used in the shock struts, shimmy dampers, and brake systems. MIL-H-83282 hydraulic fluid is colored red. It is available in 1-quart, 1-gallon, 5-gallon, and 55-gallon containers, and 16-ounce spray cans. The spray can is normally used to spray the exposed portions of oleos (the shiny part) of actuating cylinders and struts, as required during most daily inspections of aircraft. NOTE: Hydraulic fluid MIL-H-46170 is a preservative type of hydraulic fluid used in the preservation of hydraulic systems and components. While it is red in color and considered compatible with MIL-H-83282 hydraulic fluid, it should NOT be used to service aircraft hydraulic systems. Naval aircraft hydraulic systems are serviced by checking the fluid level (on a sight gauge usually located on the side of the reservoir) and filling the system to the prescribed level. Before fluid is added to this type of reservoir, the reservoir instruction plate should always be checked for the proper filling instructions. The instruction plate is attached to either the reservoir or to the aircraft structure near the filler opening of the reservoir. The instruction plate contains the following information: Total capacity of the system 5-10

Reservoir capacity Refill level Specification and color of fluid Correct position of all actuating cylinders during filling Other information considered necessary during the filling of the reservoir NOTE: After opening a can of hydraulic fluid, the entire contents should be poured into the fill stand or servicing unit immediately. This will prevent the fluid from absorbing dust and grit from the air. Aviation Hydraulics Manual, NAVAIR 01-1A-l7, requires that any remaining fluid left in the hydraulic fluid container, after servicing a fill stand/servicing unit, be discarded, and that the empty fluid container be destroyed immediately and not used to store or handle other fluids. Q13. Define viscosity. Q14. What scale is used by both the Navy and the Air Force to determine oil viscosity? Q15. What is the military specification number for the hydraulic fluid presently used in the hydraulic systems of all naval aircraft? Q16. What should be done with the fluid remaining in the can after filling a servicing unit? PNEUMATIC SERVICING Landing gear struts, hydraulic accumulators, and various air storage bottles found on most naval aircraft must be serviced with compressed air or nitrogen. These components are serviced by Aviation Structural Mechanics (AMs). You should refer to the applicable training manuals and technical manuals for in-depth discussions of the servicing of rate-peculiar components. Servicing Air Storage Bottles Nitrogen and air storage bottles are used on some aircraft for various emergency operations. These bottles are necessary for the safe operation of the aircraft and the safety of the crew. Air storage bottles are used for such functions as emergency brakes, emergency landing gear extension, and emergency canopy operation. Some aircraft have a pneumatic system that will maintain the required pressure in these bottles while in flight. However, most of these pneumatic systems require servicing on the ground with an external source of high-pressure air or nitrogen before each flight. 5-11 Air storage bottles and accumulators are serviced similarly. Most air bottles have an air filler valve and a pressure gauge. They usually require higher servicing pressures than accumulators. A high-pressure compressor and other special equipment, such as the nitrogen booster, must be used to obtain these higher pressures. Inflation of Tires For aircraft tires to perform satisfactorily, the correct air pressure must be maintained. Aircraft tires must be inflated to the pressure specified for the type of operation (ashore or afloat) that the aircraft is performing and for the gross weight of the aircraft. Air pressure must be checked daily with an accurate gauge. Tire inflation data is usually attached to the aircraft, as shown in figure 5-6. When the aircraft does not have this plate, you can find the information in the general information and servicing section of the applicable MIM. Overinflation or underinflation of aircraft tires causes specific problems. Overinflation reduces the Figure 5-6.—Tire inflation chart.

contact area of the tire, causing it to wear faster at the tread center. Failure due to carcass ruptures and breaks in the tire cords that result from contact with foreign objects are usually caused by overinflation. Underinflation increases the contact area and causes the tire to wear rapidly and unevenly at the outer edges of the tread. An underinflated tire flexes excessively and develops high temperatures that weaken tire cords. An underinflated tire also may slip on the wheel during landing and shear off the valve stem. To determine the proper inflation pressure, you should check an inflation chart like the one shown in figure 5-6. If the gross weight of an aircraft is 20,000 pounds, the correct tire pressure for that aircraft when shore based is 310 psi. If the aircraft is carrier based, the pressure is maintained at 350 psi, regardless of the gross weight. When aircraft tire pressure is low, you should add air from a regulated source. CAUTION An unregulated, high-pressure air source for tire inflation is a hazard. Tire inflation source pressure should be carefully moni- tored. If high-pressure cylinders (such as the portable air bottle or the air or nitrogen serv- icing trailer) are used, a regulator must be used to prevent inadvertent overinflation. Maintenance personnel must always use a remote inflator unit when inflating tires. The operator of this unit should always stand at right angles to the landing gear axle, directly in front or in the rear of the tire. The operator should also stand at the full length of the inflator unit hose. This will prevent the operator from being struck by pieces of the wheel if it were to fail CAUTION When an aircraft wheel is to be removed from the aircraft, maintenance personnel must deflate the tire before removing the wheel assembly from the aircraft. This precaution is necessary because of the possibility that the bolts in split-type wheels might have been sheared during landing, causing the wheel halves to separate when the axle nut is re- moved. Personnel have been killed because they failed to remove the air from the tire before removing the axle nut. Oxygen Servicing Plane captains are responsible for making sure that the liquid oxygen systems of the aircraft are serviced. Personnel in the Aviation Structural Mechanic, Safety Equipment, (AME) rating refill these converters. A typical liquid oxygen converter is shown in figure 5-7. Liquid oxygen is dangerous to handle and requires special handling procedures. These special handling procedures are discussed later in this chapter. SERVICING EQUIPMENT The following text discusses the equipment used to service aircraft, such as the high pressure air valve, servicing trailers, preoiler hand pumps, and fluid service unit HSU-1. High-Pressure Air Valve The high-pressure air valve is used to service struts, accumulators, air storage bottles, and other components serviced with high-pressure air. The high-pressure air valve, shown in figure 5-8, is used on most naval aircraft. It is referred to by its military specification (MS) number MS 28889-1. Air valve MS 28889-1 does not have a valve core. When servicing a system equipped with a high-pressure air valve, you should exercise extreme Figure 5-7.—Typical liquid oxygen converter. 5-12

Figure 5-8.—High-pressure air valve, MS 28889-1. caution. To release the air pressure from a system equipped with a high-pressure air valve, you should remove the dust cap from the valve and release the pressure by slowly turning the swivel nut counterclockwise. NOTE: Dust covers are not used in most operating squadrons because they are a foreign object damage (FOD) hazard. CAUTION When loosening the swivel nut, you should make sure that the hex body nut is either lockwired in place or held tight with a wrench. If it were to be loosened before the air pressure is relieved, serious injury to per- sonnel may result. Low pressure indicates a leak in the system. This leak must be found and corrected. When a leaking, high-pressure air valve must be replaced, a new packing must be installed with the replacement air valve assembly. Ensure the required torque, as required by the MIM, is applied to the hex body. After the hex body is torqued, it is lockwired to the component or surrounding structure, as specified in the MIM, by using the holes provided in the hex body nut. When the correct pressure has been reached in the system that is being serviced, you should secure the air valve by tightening the swivel nut in a clockwise direction. Once again, torque the swivel nut to the required torque listed in the MIM. After using the high-pressure air valve, you should secure the pressure source, remove the air/nitrogen pressure charging chuck, and replace the valve cap. Install the valve cap fingertight. Air or Nitrogen Servicing Trailer A servicing trailer, similar to the one in figure 5-9, is found at most naval air activities for servicing aircraft hydraulic and pneumatic systems. This trailer carries six air or nitrogen storage cylinders and the necessary flow-controlling mechanisms. The trailer has a 30-foot hose stowed in a box that is mounted between the top two bottles. The air or nitrogen servicing trailer has a purifier (dehydrator) assembly. This purifier assembly is essentially a reservoir that contains a chemical drying agent. The chemical drier removes moisture that may have adhered to the valves or have been accidentally introduced into the system. The chemical is contained in a metal cartridge or can, which is changed periodically. The gas passes through the drier just before it enters the servicing hose. The trailer has a set of manifold control valves and two regulator valves. The bottle on the air or nitrogen servicing trailer may be recharged by using a high-pressure compressor. NOTE: When recharging the cylinders on the air or nitrogen servicing trailer, you should ensure that the cylinder pressure does not exceed the pressure specified for the equipment being recharged. When operating the servicing trailer, you should observe the following safety precautions. When a system or component is being charged, only a qualified licensed operator should operate the trailer. Complete familiarity with the trailer is a basic prerequisite to ensure safe operating techniques. The servicing hose end and installation connection fitting should be thoroughly inspected before servicing, and any particles of foreign material removed. Never charge a system or component without the proper fusible safety plug and blowout disc in the trailer charging system. 5-13

Figure 5-9.—Air or nitrogen servicing trailer. Always know the pressure existing in the system to be filled and the pressures in all the cylinders to be used up in the cascading process before beginning a charging operation. A malfunctioning pressure regulator should be disconnected from the line, closing its associated shutoff valve. The trailer can then be operated with the remaining regulator. The charging hose must never be stretched to reach a connection. Position the trailer so the hose is not under tension while servicing an aircraft. After servicing an aircraft system, stow the servicing hose in its container to ensure that it is not damaged by dragging along behind the trailer. Preoiler (PON-6) The preoiler (PON-6) is a portable, hand-carried, hand pump with a 3-gallon capacity. Figure 5-10 shows the major components of the PON-6. It will deliver oil at a pressure up to 100 psi. A sight glass (not shown in fig. 5-10) is located on the side of the reservoir and shows the level of the oil. An oil pressure gauge indicates oil line pressure. An oil meter records the amount of oil delivered. The meter is calibrated in ounces (outer scale) and quarts (inner scale). A push-button bleed valve relieves pressure on the meter and service hose and bleeds oil back to the reservoir. The service hose is 6 feet long. A complete drain bottle assembly is provided for overflow oil from the aircraft 5-14

system. All components are rigidly mounted in a steel tubular framework. Fluid Service Unit Model HSU-1 The hydraulic fluid service unit, Model HSU-1, is shown in figure 5-11. It has a fluid-holding capacity of 3 gallons. This unit accepts a standard l-gallon container, and it contains an integral 2-gallon reservoir assembly. The HSU-1 has a replaceable, 3-micron, disposable filter incorporated to ensure delivery of contamination-free fluid. Figure 5-10.—Preoiler PON-6. The 2-gallon reservoir assembly (along with a hand pump assembly) is mounted to a cast aluminum base. The lower can piercer is mounted on top of the reservoir and allows fluid to flow from the installed l-gallon container into the reservoir, automatically replenishing it. A sight gauge indicates the fluid level of the reservoir. It reads from 0 to 2 gallons in l/4-gallon increments. An indicated level of 2 gallons or less means that the l-gallon container is empty and can be removed for replacement. A capped deaeration port is located on top of the reservoir to permit bleeding the air from the pump and output hose. Figure 5-11.—Fluid service unit, Model HSU-1. 5-15

The can-holder and handle assemblies are mounted above the 2-gallon reservoir. The can holder positions the installed l-gallon fluid container directly above the reservoir. Also, it provides a means of placing the handle assembly over the container top. The handle assembly is hinged to a bracket on the can-holder assembly. It has a spring-loaded latch to lock the handle in the closed position. In addition to the carrying handle, the handle assembly contains an upper can piercer, a vent check valve, and a filter. A vent hose is connected between the top of the reservoir (sight gauge) and the upper can piercer. Fluid is delivered by a hand pump. The pump can deliver 1.5 fluid ounces per full stroke at 0 to 250 psi. The pump is operated with a sliding pump handle, which is held in the extended or retracted position by a spring-loaded ball detent. The 3-micron filter on the pump base removes particulate contamination from the hydraulic fluid being delivered to the suction side of the pump. The filter unseats a shutoff valve, which closes the suction port when the filter element is being replaced. The HSU-1 service unit has a 7-foot service hose connected to the unit’s fluid output port at the pump assembly. The hose assembly ends with a short bent-tube assembly for direct connection to fill fittings on the aircraft or components being serviced. A 3-micron, in-line filter located between the hose end and the tube prevents reverse-flow contamination and serves as a final filter. When the fluid service unit is not in use, it is stored by wrapping the hose assembly around the can-holder assembly and fastening the tube end to the hose storage fitting on the base. This keeps contaminants from entering the hose while the unit is not in use. 5-16 Q17. The air pressure in aircraft tires must be checked how often? Q18. Why is it important for the operator of the remote inflator unit to stand directly fore or aft of the tire being inflated? Q19. Why must a tire be deflated prior to removing a wheel assembly from an aircraft? Q20. Liquid oxygen converters are refilled by personnel from what rating? Q21. The high-pressure air valve, shown in figure 5-8. is used on most naval aircraft for what purpose? Q22. What purpose does the purifier serve on the nitrogen servicing trailer? Q23. What is the holding capacity of the fluid servicing unit (HSU-1)? SAFETY LEARNING OBJECTIVE: Identify safety precautions used when working around aircraft on the flight line and aboard ship. Safety is the responsibility of everyone in the Navy. You are responsible for your own safety, and, as a sailor, you have the moral responsibility for the safety of your shipmates. As a plane captain, you will be exposed to dangerous situations. In fact, many insurance companies rate flight line operations and, in particular, the flight deck environment among the most dangerous jobs in the world. The following text will introduce you to some of the many hazards of your work area. LINE SAFETY PRECAUTIONS In addition to the more specific safety precautions presented in various sections of this chapter, there are a number of miscellaneous precautions that you must observe when working on the aircraft flight line and the carrier flight deck. The following precautions are of special importance to ensure your safety as well as the safety of your coworkers. Propellers and Rotors When working on the line around propeller-driven aircraft or helicopter rotors, the first general precaution that you must observe is to BEWARE OF PROPELLERS. When you see a propeller, let it be a constant reminder to STAY CLEAR! In general, do not cross in front of moving propellers because they are not easily seen. A good habit is to always walk around propellers. Unless you are inspecting or performing maintenance on the propeller blades, NEVER walk through a prop arc, even when it is not operating. The area around the aircraft must be kept clear of loose gear and debris. Intake Ducts Maintenance of jet engines presents major hazards. The air intake duct of operating jet engines represents an ever-present hazard to personnel working near the inlet duct of the aircraft. It can also be a hazard to the engine itself if the turnup area around the front of the aircraft is not kept clear of debris. Jet

engines will “eat” anything and they have no respect for life or limb. This hazard is greatest during maximum power settings (high-power turnup). The air inlet duct may develop enough suction to pull hats, eyeglasses, loose clothing, and rags from pockets. Secure or remove all loose articles before working around operating jet engines. In some engines, the suction is strong enough to pull a person up to or, in some cases, into the inlet and pull the eyeballs from their sockets. Keep clear of the intakes. Protective screens (fig. 5-12) are supplied as part of the ground handling equipment for most jet aircraft. These screens should be installed before all maintenance turnup. Turnup screens protect both personnel and engines. It does NOT eliminate the need for caution; serious injury can still result by being Figure 5-12.—Engine inlet protective screen. 5-17

pulled against the screen, and small items can be pulled through the screen. This results in thousands of dollars of damage to the engine. Exhaust Area Hazards Jet engine exhaust also creates hazards. Tests show that while the carbon monoxide content of jet exhaust is low, other gases are present that irritate the eyes. Less noticeable, but as important, is the respiratory irritation that may be caused by exhaust fumes. The two major hazards of jet engine exhaust are the high temperature and high velocity of the exhaust gases from the tailpipe. High temperatures are found up to several hundred feet from the tailpipe, depending on wind conditions. Closer to the aircraft, temperatures are high enough to damage asphalt pavement. The blast from the exhaust is strong enough to knock a person down at close distances and can even blow a body off of the flight deck overboard. Do not take the signs lightly. BEWARE OF JET BLAST. When a jet engine is started, excess fuel accumulates in the tailpipe. When the fuel ignites, long flames can be blown out of the tailpipe. All flight line personnel should be aware of this hazard, and all flammable materials should be kept clear of the danger area. During maximum power settings, the high velocity of the exhaust gases may pick up and blow loose dirt, sizable rocks, sand, and debris several hundred feet. This is an eye and FOD hazard. Therefore, you should use caution when parking an aircraft for run-up. The general information section of the applicable MIM contains information concerning the exhaust area hazards. These instructions should be strictly followed. No one should foolishly experiment with the specified safety margins. After engine operation, no work should be done to the exhaust section for AT LEAST ONE-HALF HOUR (preferably longer). If work is necessary immediately, you must wear leather gloves. Engine Noise Jet engines produce noise capable of causing temporary as well as permanent loss of high-frequency hearing. When working around jet engines, you should take the following precautions to protect your hearing: Wear the proper ear protection (ear plugs or sound attenuators and sometimes both). Do not exceed the time limits on exposure to the various sound intensities. Have periodic checks on your hearing ability. Engine noise is broadcast from the aircraft in patterns, which vary in direction, distance, and intensity with engine speed. The most intense sound areas are in the shape of two lobes extending out and aft from the aircraft center line. However, dangerous intensities are also present to the side and forward of the aircraft. (See fig. 5-13) This information is found in the applicable Naval Air Training and Operating Procedures Standardization (NATOPS) manual. Damage to hearing occurs when the ear is exposed to high sound intensities for excessive periods. The higher the sound intensity, the shorter the period of exposure that will produce damage. Above 140 decibel (dB) sound intensity, any exposure without ear protection can cause damage. NOTE: Sound intensity is measured in decibels (dB). A dB is a number that relates a given sound intensity to the smallest intensity that the average person can hear. By wearing regulation earplugs or sound attenuators, you can raise the limits of time exposure. Personnel working within danger areas should be familiar with calculated noise dB levels (as specified in the applicable MIM), and should wear the necessary protective equipment. Q24. Q25. Q26. Q27. Q28. According to many insurance companies, what is considered the most dangerous environment in the world? When you work around aircraft with propellers, when is it safe to walk through or stand in the prop arc? Does a protective screen over the inlet of an operating aircraft engine eliminate the possibility of serious injury? What are the two major hazards of jet engine exhaust? Any exposure, without ear protection, can cause hearing damage above what decibel (dB) level? Movable Surface Hazards Moveable surfaces, such as flight control surfaces, speed brakes, power-operated canopies, and landing gear doors, are a major hazard to flight line personnel. These units are normally operated during ground 5-18

Figure 5-13.—Noise danger areas. operations and maintenance. Therefore, you should make sure that all personnel and equipment are clear of the area before operating any movable surface. Power-operated canopies have safety locks that must be installed during ground-handling operations. These safety locks prevent the accidental closing of the canopy, preventing personnel from being crushed as the canopy closes. The general information and servicing section of each MIM contains specific information concerning the various movable surface hazards and specifies the safety locks that must be used. Personnel involved with line operations and maintenance should pay 5-19

particular attention to this information because some of these units move extremely fast with terrific power. Seat Ejection Mechanisms You must strictly observe all safety precautions when working around an aircraft equipped with an ejection seat. These safety precautions cannot be overemphasized because accidental actuation of the firing mechanism can result in death or serious injury to anyone in the cockpit area. Each ejection seat has several ground safety pins; the exact number depends upon the type of seat. These safety pins are provided on red-flagged lanyards for use at every point of potential danger. They must be installed when the aircraft is on the ground or deck, and must never be removed until the aircraft is ready for flight. Always keep in mind the following general precautions when you are working on or around ejection seats: Treat ejection seats with the same respect as a loaded gun. Always consider an ejection seat system loaded and armed. Before entering a cockpit, know where the ejection seat safety pins are and be certain they are installed. Only authorized personnel may work on ejection seats and components and only in an authorized area. Overheated Wheel Brakes If an aircraft has been subjected to excessive braking, the wheels may be heated to the point there is danger of a blowout or fire. NOTE: Excessive brake heating weakens the tire and wheel structure, increases tire pressure, and creates the possibility of fire in magnesium wheels. When the brakes on an aircraft have been used excessively, the fire department should be notified immediately. All unnecessary personnel should leave the immediate area. If blowout screens, such as the one shown in figure 5-14, are available, they should be placed around both Figure 5-14.—Blowout screen for overheated brakes. 5-20

main wheels. These screens help prevent damage or injury if a blowout occurs. If the tire is flat, explosive failure of the wheel or tire will not result. However, upon sudden cooling, an overheated wheel may fracture or fly apart, which could hurl bolts or fragments through the air with sufficient speed to injure personnel. Required personnel should approach overheated wheels with extreme caution in the fore or aft directions—never in line with the axle. NOTE: The area on both sides of the tire and wheel, in line with the axle, is where the fragments would be hurled if the tire were to explode. Therefore, it is called the danger area (fig. 5-14). Heat transfer to the wheel will continue until the brake is cooled. Therefore, the danger of explosive failure may exist after the aircraft is secured if the overheated brake is not cooled. The recommended procedure for cooling overheated wheel, brake, and tire assemblies is to park the aircraft in an isolated location. Then, allow the assembly to cool in ambient air for 45 to 60 minutes. Cooling agents should not be used to accelerate cooling unless operational necessity dictates their use. If such an operational necessity were to occur, the cooling should be supervised by someone in the AM rating. WARNING Never use CO2 to cool overheated brakes. A violent explosion can occur. Liquid Oxygen (LOX) When working with or around liquid oxygen, you must take the following safety precautions: Do not operate liquid oxygen equipment unless you are qualified, licensed, or working under the supervision of qualified personnel. Do not permit smoking, open flames, or sparks in the liquid oxygen handling areas. Do not carry matches in liquid oxygen handling areas. Always call oxygen by its proper name. Do not confuse it with compressed air. Never use oxygen in place of compressed air for any purpose. Handle converters, storage tanks, and transfer equipment with care to avoid damage to the insulating space. Keep work areas and equipment free from oil, grease, or any other combustible material. Keep tools and clothing free from oil and grease. Avoid spilling liquid oxygen on the floor or deck areas. In case of accidental spillage, ventilate the area thoroughly. If the body comes into contact with liquid oxygen or there is reason to suspect some part of the body has been frozen or chilled, thaw the exposed area, preferably by immersion or by bathing it in water that is slightly above normal body temperature. Then wrap the exposed area loosely with a clean, dry dressing. Report to a doctor immediately. Do not apply anything else to the affected area other than a clean, dry dressing. CAUTION Liquid oxygen can explode when it comes into contact with oil or grease. LOX Protective Clothing Protective clothing allows you to work safely with LOX. Wear clothing in the following ways: Wear goggles or safety glasses with side shields or a face shield when handling LOX. If LOX is spilled on clothing, remove the clothing immediately and air it promptly. In general, wear all clothing so that, if there were spillage, the liquid would roll off the clothing and not become trapped in gloves, shoes, or pockets. Other items of protective clothing are plastic or rubberized fabric aprons, high-top shoes or rubber boots, and cuffless trousers worn outside the shoe tops. The clothing should not have pockets, and sleeves and trousers should not be rolled up. Do not handle with your bare hands any tubing or fittings through which LOX is flowing. Wear clean, dry gloves when handling parts of equipment cooled by LOX. Use loose-fitting leather gloves so they can be thrown off quickly if any of the LOX gets into them. 5-21

FLIGHT DECK SAFETY The flight deck of an aircraft carrier is a very busy and dangerous place during launching, recovery, and respotting of aircraft. Plane captains and other maintenance personnel assigned specific duties associated with the flight deck must be constantly aware of the dangerous environment in which they work. You should receive predeployment training lectures on aircraft handling procedures, flight and hangar deck safety precautions, responsibilities during launch and recovery of aircraft, tie-down requirements and techniques, and special shipboard maintenance procedures and safety precautions. This training requirement is in addition to the general indoctrination given all personnel concerning flight quarters, general quarters, fire, abandon ship, man overboard, and other general drills. Also, this indoctrination covers ship conditions, smoking and safety precautions, and watchstanding requirements peculiar to shipboard operations. Flight line safety precautions (previously discussed) apply to flight deck operations. The primary difference is the limited space and tempo of operations experienced on the flight deck, causing flight deck operations to be more dangerous. During launch and recovery of aircraft, all personnel not required should leave the flight deck and catwalk areas. The safe parking area aft of the island is also an unauthorized space for personnel during aircraft recovery. Personnel should not stand in or otherwise block entrances to the island structure or exits leading off the catwalks. Never turn your back on aircraft taxiing on the flight deck. Always be alert for the unexpected. There is never room for carelessness, daydreaming, or skylarking on the flight deck. All personnel assigned flight quarters on or above the hangar deck must wear appropriate jerseys and helmets. Personnel on the flight deck during flight quarters must wear the cranial impact helmet or its equivalent, goggles, sound attenuators, flight deck shoes, flotation gear, an adequately secured whistle, and a survival light. The authorized flight quarters clothing for the different flight deck jobs is shown in figure 5-15. Any maintenance performed on aircraft that will require wingspread/fold, respot, turnup, blade track, jacking, or maintenance that will prevent the aircraft from being moved must be approved through the activity’s maintenance control. This is true regardless of how much or how little time is required for the work to be performed. The activity’s maintenance control, before it can grant approval, must obtain permission from the aircraft handling officer by way of the air wing, group maintenance liaison officer, or his or her representative. When an aircraft is being turned up or jacking operations are being performed, make sure that the permission of the aircraft handling officer has been received and that all ship’s safety regulations are observed. Safety men, with sufficient line to block off the area, must be stationed around the aircraft. Each ship may have safety precautions unique to that ship due to operational requirements and special circumstances. Petty officers are responsible for knowing and enforcing the safety precautions that apply to their area of work and their personnel. Q29. Q30. Q31. Q32. Q33. What system or mechanism should you always treat with the same respect as a loaded gun? In relation to overheated wheel brakes, what area is considered the “danger area”? What item, if used to cool overheated brakes, is likely to cause an explosion? Why is it important to keep tools, work areas, and clothing free from grease and oil when working around LOX? What are the primary differences between flight line and flight deck operations? SPECIAL PROGRAMS LEARNING OBJECTIVE: Identify the Navy’s special maintenance programs related to Naval Aviation and their purposes. The special programs discussed in this chapter are covered in detail in the Naval Aviation Maintenance Program, OPNAVINST 4790.2. Until Volume V of OPNAVINST 4790.2 is issued, which covers Naval Aviation Maintenance Standard Operation Procedures (NAMSOP), a local, more convenient source of information on these special programs is your squadron maintenance instructions (MIs). Technical information and local policy are issued through MIs. MIs describe techniques that do not direct the performance of work at defined intervals but are sustaining in nature. MIs include policy, procedures, and methods of managing specific maintenance 5-22

PERSONNEL HELMET FLOTATION VEST SYMBOLS, FRONT AND BACK Aircraft handling crew and chock men Blue Blue Crew number Aircraft handling officers and plane Yellow Yellow Billet title—crew number (note 1) directors Arresting gear crew Green Green A Aviation fuels crew Purple Purple F Cargo handling personnel White Green “SUPPLY”/“POSTAL” as appropriate Catapult and arresting gear officers Green Yellow Billet title Catapult crew Green Green C Catapult/AG QA Green White ALRE QA Catapult safety observer (ICCS) Green (Note 4) Billet title Crash and salvage crews Red Red Crash/Salvage Elevator operators White Blue E Explosive ordnance disposal (EOD) Red Red “EOD” in black GSE troubleshooter Green Green “GSE” Helicopter LSE Text Text Text Helicopter plane captain Red Brown H Hook runner Green Green A Landing signal officer None White LSO Leading petty officers: Line Geen Brown Maintenance Green Green Quality assurance Brown White Squadron plane inspector Squadron designator and “Line COP” Squadron designator plus “Maint. COP” Squadron designator and “QA” Green White Black and white checkerboard pattern and squadron designator LOX crew White White LOX Maintenance crews Green Green Black stripe and squadron designator Medical White White Red cross Messengers and telephone talkers White Blue T Ordnance Red Red 3-inch black stripe and squadron designator/ships billet title Ordnance QA White (Note 6) Squadron designator and “ORDNANCE QA/SAFETY” Photographers Green Green P Plane captains Brown Brown Squadron designator Safety White White “SAFETY” Figure 5-15.—Authorized flight quarters clothing. 5-23

HELMET FLOTATION VEST SYMBOLS, FRONT AND BACK “SUPPLY COORDINATOR” PERSONNEL Supply VERTREP coordinator White Green Tractor driver Blue Blue Tractor Tractor king Blue (Note 5) TK Transfer officer White White “TRANSFER OFFICER” 1. Only personnel charged with the actual control or direction of aircraft movements on the flight or hangar deck shall wear yellow jerseys. Personnel in charge of a detail, such as aviation fuels, ordnance, and maintenance, shall wear a helmet and jersey corresponding in color to that of their respective detail and with their billet title on the jersey and flotation vest. 2. Helmets for the following personnel shall be marked with three reflective international orange stripes, one inch wide, evenly spaced, running fore and aft: a. All air department officers. b. Air department chief petty officers and leading petty officers. c. EOD team members. d. All ordnance officers and gunners. e. Ordnance handling officer and air gunner. 3. Helmets for all other personnel shall be marked with a 6-inch square (or equivalent) of white reflective tape on the back shell and a 3-inch by 6-inch (or equivalent) of white reflective tape on the front shell. Landing signal officers are not requi red to wear helmets or sound attenuators when engaged in aircraft control. Helmets shall have a 2-inch piece of velcro on the left side of the front shell and velcro on the survival light. 4. New requirement for ICCS is green jersey and yellow vest. 5. Yellow jersey/blue flotation vest. 6. White jersey/red flotation vest. Figure 5-15.—Authorized flight quarters clothing—Continued. programs. When issued, the NAMSOP will eliminate the need for maintenance instructions at command level. NAMSOPs will standardize these programs throughout aviation maintenance. As a plane captain, you will be involved with these programs. Therefore, you must know the purpose and scope of the special programs discussed in the following text. FOREIGN OBJECT DAMAGE (FOD) PREVENTION PROGRAM FOD is damage to aeronautical equipment caused by objects and debris foreign to that equipment. Foreign objects are also major safety hazards to personnel if the objects are left on the flight line/flight deck to be blown around by aircraft. The ingestion of foreign objects and debris into gas turbine engines is a problem that accounts for the largest percentage of premature engine removal. The removal of these engines consumes maintenance man-hours, imposes unscheduled workloads on supporting activities, and creates an unwarranted shortage of engines and spare engine parts in the supply system. Thus, the training capability and fleet operational readiness are drastically reduced. The majority of gas turbine engines undergoing depot rework exhibit some degree of FOD. Most FOD is caused by poor housekeeping, facility deterioration, improper maintenance practices, and carelessness. FOD cannot be tolerated; thus, the requirement to reduce FOD is mandatory. A successful FOD prevention program depends upon command support, personnel knowledge and awareness, and its integration into the total maintenance effort. As a plane captain, you can help prevent FOD by checking the deck for loose gear (nuts, bolts, washers, and safety wire) after maintenance is completed. Also, you should check the intakes and exhausts of your aircraft during the daily/turnaround inspection. TOOL CONTROL PROGRAM (TCP) The Tool Control Program (TCP) reduces the potential for tool FOD-related mishaps and keeps down the cost of tool replacement. This program gives you a fast way to account for all tools, both before and 5-24

after completing a maintenance task on an aircraft or its related equipment. The material control officer coordinates the Tool Control Program and makes sure that tools are procured and issued according to the approved tool control plan (TCPL). A TCPL contains information that includes material requirements, tool inventories, and detailed instructions for operation of the TCP for a specific type/model of aircraft. The TCP is based upon the instant inventory concept. It provides internally configured, silhouetted tool containers. All tools have individual locations to highlight a missing tool. An inventory listing is included within each container. On containers that cannot be silhouetted, a note with the inventory and drawing of the container outline is fastened to the container. It is securely fastened so it will not become a FOD hazard. Either system lets you quickly determine that all tools have been retrieved after a maintenance action. The most significant benefit of this program is the saving of lives and equipment by eliminating tool FOD-caused accidents. Additional benefits of the Tool Control Program are listed below. Reduced initial outfitting and tool replacement costs Reduced tool pilferage Reduced man-hours required to complete each maintenance task Assurance that proper tools are available for specific maintenance tasks METROLOGY AND CALIBRATION PROGRAM (METCAL) Most maintenance shops are provided with a variety of calibrated support equipment that is used to maintain many different systems. This calibrated SE is used to measure, gauge, test, inspect, or otherwise examine material, supplies, and equipment to determine compliance with requirements established in technical documents. The accuracy of this equipment is vital in everyday maintenance. The METCAL program was designed to make sure that all equipment requiring calibration/servicing is maintained at maximum dependability. The recall of equipment for calibration at established intervals is assisted by the Metrology Automated System for Uniform Recall and Reporting (MEASURE). The MEASURE goal is to provide a single, uniform management information system for the Navy METCAL Program. As a plane captain, you are responsible for checking each piece of equipment (hydraulic servicing unit, oil servicing unit, etc.) to make sure that the calibration label is valid (has the current date on it). If you find an out-of-date calibration label, the piece of equipment should not be used, and you should make an immediate report to your supervisor. JOINT OIL ANALYSIS PROGRAM (JOAP) The Joint Oil Analysis Program (JOAP) was designed so the oil condition of equipment can be diagnosed and monitored without removing or extensively disassembling equipment. As a plane captain, you will be directed by maintenance control through a Visual Information Display System/Maintenance Action Form (VIDS/MAF) or NALCOMIS to take an oil sample. The oil sample you take might be from a certain aircraft engine, transmission, or other aircraft component. You must be careful when taking the sample. You must be sure that you do not cause the sample to become contaminated. Additionally, you must fill out an Oil Analysis Request Form (DD Form 2026), shown in figure 5-16. After you have completed this form, the sample is sent to the appropriate oil laboratory where it is checked for contamination. If contamination is present in the sample, corrective action is taken. HYDRAULIC CONTAMINATION CONTROL PROGRAM Hydraulic fluid contamination is the presence of undesirable foreign matter, which may or may not be visible to the unaided eye. Typical fluid contaminants include metallic and nonmetallic debris (both self-generated and externally introduced), water, and other foreign fluids. This contamination degrades system performance and component life. The Hydraulic Contamination Control Program also includes other systems that contain fluid. Examples are the F-14 aircraft’s radar liquid coolant and missile coolant systems. Also, some pieces of SE are included in this program. Hydraulic system contamination levels are monitored by means of a fluid surveillance program. When systems fail to meet required cleanliness levels, decontamination procedures are used to restore systems to an acceptable level. The acceptable contamination levels, related maintenance doctrine, and detailed maintenance requirements are specified in the Aviation Hydraulics Manual, NAVAIR 01-1A-17. 5-25

Figure 5-16.—Oil Analysis Request, DD Form 2026. The prime objective of the Hydraulic thereby providing for safe and efficient operation of Contamination Control Program is to maintain a naval aircraft and SE. Undetected and uncontrolled satisfactory level of fluid purity in hydraulic systems, contamination in an aircraft hydraulic system poses a 5-26

serious threat to flight safety. This program is an ongoing effort to control hydraulic fluid contamination. AIRCRAFT FUEL SURVEILLANCE PROGRAM Foreign contaminants and water in aircraft fuel systems constitute a major hazard in naval aircraft. Harmful effects of water, particulates, and microbiological growth include erratic or incorrect fuel quantity indications; icing of filters, valves, and other fuel system components; engine failure caused by carburetor/fuel control icing or malfunction; and jet engine starting difficulties. Further, if contamination remains undetected, rubber fuel cells deteriorate and become permanently damaged. Constant vigilance by maintenance personnel is required to ensure that clear, bright, and dry fuel is delivered to the aircraft, and subsequently to its engines. All aviation fuels are produced under rigidly controlled specifications. To maintain its high quality, maintenance personnel must take careful and continual measures to prevent contamination. Contamination can occur from fuel mixing with other bulk petroleum products as well as from dirt, rust, and water. Serious engine and airframe problems develop if inadequate attention and effort are given to maintaining fuel quality. Since no two fuel systems are identical, it is not possible to establish rigid and detailed procedures that will apply in all situations. The plane captain takes fuel samples from low-point drains of all fuel cells/tanks before the first flight of the day. This action is normally accomplished during the daily inspection. This also includes any auxiliary, external, or in-flight refueling tanks. Additional information on this program can be obtained in the Aircraft Refueling NATOPS Manual, NAVAIR 00-80T-109. Q34. What builds a successful FOD program? Q35. What officer coordinates the Tool Control Program? Q36. What is the most significant benefit to the Tool Control Program? Q37. What is the prime objective of the hydraulic contamination control program? Q38. What publication contains detailed information on the Aircraft Fuel Surveillance Program? AVIATORS BREATHING OXYGEN (ABO) SURVEILLANCE PROGRAM Aviator’s breathing oxygen (ABO) comes in both gaseous and liquid states. Liquid oxygen (LOX) is converted to a gaseous state before its delivery to the aircrew. Because oxygen can be contaminated easily, LOX requires frequent and continual monitoring by personnel to ensure detection of contamination. The safety of the aircrew is of the utmost priority. An oxygen surveillance program is the primary method of ensuring that each operation in the LOX supply system is carried out in strict compliance with established procedures. Surveillance begins with procurement or generation of LOX and continues throughout storage, handling, transfer, and servicing in the aircraft. This program is also applicable to all naval activities involved in the support and manufacture of LOX and related equipment. Each person associated with the Aviation Breathing Oxygen Surveillance and Contamination Program should have a thorough knowledge of the characteristics of liquid oxygen and gaseous oxygen and the hazards of contamination. Each person should also know the quality standards listed in the ABO Surveillance Program Laboratory Manual and Field Guide, A6-332A0-GYD-000. EGRESS SYSTEM CHECKOUT PROGRAM The high-performance aircraft used by the Navy places extreme demands on emergency escape systems. These systems contain high-explosive devices that are designed for onetime use only. Actuation of these devices could result in severe injury or death to personnel and damage to or destruction of aircraft. Therefore, because of the inherent dangers associated with ejection seats and canopy systems, an egress systems checkout procedure is required. The egress/environmental work center (AME shop) indoctrinates all personnel in the hazards and safety precautions associated with these systems. A system checkout must be given by a qualified AME to all new maintenance personnel before they perform any aircraft maintenance work. Maintenance personnel must be checked out every 6 months thereafter before the last day of the requalification month. In addition, any personnel removed from aircraft maintenance responsibilities for more than 90 5-27

days must receive an egress system checkout before performing any aircraft maintenance. The egress/environmental work center and the other maintenance work centers maintain records of system checkouts. including date given, date due, and the signature of the AME performing the checkout. The plane captain must make sure that new personnel assigned to him or her for training have a current egress system checkout before entering the cockpit. ELECTROSTATIC DISCHARGE (ESD) CONTROL/PREVENTION PROGRAM ESD is the transfer of electrostatic charge between bodies at different electrostatic potentials. This is caused by direct contact or induced by an electrostatic field. ESD-safe areas are required in such areas as supply. production control, and maintenance shops. In these areas, the technician is tied to a soft ground that reduces high current flow for personal safety. The QA division ensures the following guidelines are followed in the work center. All work centers involved in avionic maintenance and handling of ESD-sensitive assemblies have ESD training programs. ESD protective equipment and materials are used to ensure personnel and equipment safety. WARNING For personnel safety, all energized equip- ment must be isolated from the work station mat and other conductive material. TRAINING PROGRAM The Navy places great emphasis on effective and continual training. A supervisor in a maintenance activity has an ongoing responsibility for training his or her personnel. An efficient training program minimizes the loss when experienced maintenance personnel transfer from the activity. Since the activity's operational readiness depends largely on the capability of the maintenance department, the quality of the training program is important. In-service training is a command responsibility. Since this training represents a major contribution to the Navy’s overall training effort, a systematic in-service training program must be conducted. In-service training is conducted in two methods-formal and informal. Formal in-service training is conducted through formal lectures and computer-based training (CBT). Informal in-service training is conducted through the performance of on-the-job training (OJT) and the completion of Personal Qualification Standards and required reading. As a plane captain, you will be exposed to all types of training. Portions of this training will improve your skills as a plane captain and prepare you for further advancement. Other portions of this training, such as fire fighting, may, in an emergency situation, save your life. You should always learn all you can in any training situation. HEARING CONSERVATION PROGRAM Hearing loss is a source of concern within the Navy, both ashore and afloat. Hearing loss can occur from exposure to impulse or blast noise (gunfire, rockets, etc.) or from continuous or intermittent sounds, such as jet engines or machinery noise in industrial-type activities. Such loss may be temporary, disappearing after a brief period of nonexposure, or it may become permanent through repeated exposures to intense noise levels. Hearing loss caused by exposure to hazardous noise and the high cost of associated compensation claims pose a significant problem, which requires action to reduce or eliminate hazardous noise levels. Your responsibilities as a plane captain make it impossible for you to avoid noise in day-to-day flight operations, but you are provided with the means of protecting your hearing. Always wear your sound attenuators (often referred to as ears) and follow the rules for noise exposure for the type of aircraft you are working on. The hearing conservation program is outlined in Navy Occupational Safety and Health Program Manual, OPNAVINST 5100.23, and has established as its goal the elimination and prevention of hearing loss. RECOVERY AND RECLAMATION OF CRASH-DAMAGED AIRCRAFT Aircraft accidents/incidents involving exposure to gross amounts of salt water. fire-extinguishing agents, or other corrosive agents require emergency action to 5-28

prevent further damage to the aircraft and/or systems. The majority of emergency reclamation actions are caused by carelessness or the lazy attitudes of individuals. For example, overhead sprinkler systems are often triggered by improper use of ground support equipment (exhausts not vented properly). Failure to close a canopy on an aircraft compounds the problem by making the aircraft subject to water damage. Proper training or supervision should keep reclamation actions to a minimum. General procedures and basic policies for the recovery, reclamation, and transfer of crash-damaged aircraft are contained in The Naval Aviation Safety Program, OPNAVINST 3750.6; Aircraft Material Condition Definitions, Mission-Essential Subsystems Matrices (MESMs), and Mission Descriptions, OPNAVINST 5442.4; and Policy and Procedures for Aircraft, Aircraft Engines and Related Aeronautical Items Reclamation and Disposal Program, NAVAIRINST 4500.11. These publications are available on a need-to-know basis only. SUPPORT EQUIPMENT TRAINING AND LICENSING PROGRAM The assistant aircraft maintenance officer manages the Support Equipment (SE) Training and Licensing Program. The quality assurance (QA) division monitors it. The results of improper use of support equipment are excessive ground handling accidents, excessive repair costs to equipment and aircraft, the reduction of operational readiness, and personnel injuries-the most expensive cost of all. The major reason for the improper use of SE is attributed to the lack of training and effective supervision. The training program consists of classroom training conducted by the supporting activity’s AIMD, on-the-job training, and completing any personnel qualification standard (PQS) for that equipment. Classroom training is given so that personnel will know the proper operation and organizational maintenance for a particular piece of support equipment. Upon satisfactory completion of the training conducted by the supporting activity, a completion certificate for the individual trained on a specific item of SE is forwarded to the permanent activity. The activity, upon receiving the completion certificate, forwards it to the appropriate division officer. The division officer ensures that the individual has received the appropriate amount of “on aircraft” training to become qualified to use the specific unit of SE. The Restriction block on the SE license must identify the type, model, and series of aircraft on which the equipment can be used. Once satisfied that the individual is qualified, the division officer will endorse the completion certificate and initiate the support equipment operator’s license (fig. 5-17). The individual will sign the license, and then it is forwarded to the maintenance officer for signature. Each piece of equipment must be itemized; for example, NC8, NC1O, etc. Any license containing general equipment statements (aircraft tow tractor, mobile electric power plant, etc.) is not valid. Only one item per line is listed. After the signatures have been obtained, the license issued is valid for 3 years for equipment and aircraft regardless of the activity to which the licensee is assigned. Activities honoring licenses issued by other commands verify the operator’s proficiency before allowing the individual use of the equipment. Transfer to an activity operating the same SE detailed on the license, but with a different type/model aircraft, invalidates the license. Transfer to an activity operating the same type/model but a different series merely requires verification of proficiency. License renewal on a new card, whether issued at the time of expiration or transfer, is granted only after a new determination of qualifications has been made. Qualification for license renewal consists of passing the same written and practical tests used for initial licensing to ensure equipment O-level maintenance/operation and on-aircraft proficiency. Failure requires personnel to repeat the course of instruction for the equipment concerned. The expiration date for each specific type of SE is noted in column 8B on the license. The "Date Expires" block on the front of the license should be marked "NA." Commanding officers (COs) of issuing activities may, as conditions warrant, require personnel in their activities to be requalified sooner. SUPPORT EQUIPMENT MISUSE/ABUSE PROGRAM Support Equipment Misuse/Abuse forms can be submitted by anyone witnessing misuse or abuse (fig. 5-18). The division of the individual originating the report retains a copy of the Support Equipment Misuse/Abuse report, and the original report is sent to the organization that has Individual Material Readiness List (IMRL) reporting responsibility for the 5-29

Figure 5-17.—CSN Aviation Support Equipment Operators’ License. SE. Also, a copy of the report is sent to the commanding officer of the command to which the offender is attached and/or the commanding officer of the command that held custody of the item where the misuse or abuse occurred for appropriate action. As a minimum, the QA division of the command receiving the report conducts an investigation. QA also performs analysis to provide appropriate recommendations for corrective action. Reports will be returned to the command having IMRL reporting responsibility within 10 working days. Q39. Q40. Q41. Q42. Any personnel removed from aircraft maintenance responsibilities for more than how many days must receive a egress system checkout prior to performing aircraft maintenance? What manual outlines the hearing conservation program? What person manages the Support Equipment Training and Licensing Program? Who initiates a Support Equipment Misuse/Abuse form? 5-30

Figure 5-18.—Support Equipment Misuse/Abuse Form (OPNAV 4790/108). 5-31

AIRCRAFT INSPECTIONS LEARNING OBJECTIVE: Define the types of aircraft inspections required for proper maintenance and safety of naval aircraft. Aircraft are subject to a variety of stresses, strains, vibrations, and detrimental environments. If not inspected regularly, the aircraft would soon become inoperable. Maintenance is performed in conjunction with inspections. This enables the aircraft to be flown safely until the next inspection. The types of inspections that are performed by activities responsible for the maintenance of naval aircraft are defined in the following paragraphs. Acceptance inspection. This inspection is performed at the time a reporting custodian accepts a newly assigned aircraft, and upon receipt of or return of an aircraft from standard depot level maintenance (SDLM) or other major depot level work. It includes an inventory of all equipment listed in the Aircraft Inventory Record (AIR), a configuration verification, hydraulic fluid sampling, and a full systems functional check flight (FCF). It also includes an inspection of emergency systems and egress equipment. This should include functionally checking such items as fuel, oil. hydraulic shutoff valves, and prop feathering, as well as the verification of cartridge-actuated devices (CADS) and aircrew escape propulsion systems (AEPSs). In addition, a daily inspection, as required by the applicable Planned Maintenance System (PMS) publication, should also be done. Activities may elect to increase the depth of inspection if the equipment condition indicates such action is warranted. Transfer inspection. This inspection is performed at the time a reporting custodian transfers an aircraft, including transfers to SDLM. It includes an inventory of all equipment listed in the AIR, verification of CADS and AEPS, a configuration verification, hydraulic fluid sampling, and a daily inspection as required by the applicable PMS publication. Activities may elect to increase the depth of inspection if the equipment condition indicates such action is warranted. Daily inspection. Daily inspections are accomplished between the last flight of the day and the next scheduled flight. The daily inspection is valid for a period of 72 hours, provided no flight occurs during this period and no maintenance other than servicing has been performed. If more than 72 hours elapse between the inspection and the next flight, the inspection must be repeated. This inspection is performed to check equipment that requires a daily verification of satisfactory functioning. It also involves the search for and correction of relatively minor problems to prevent their progressing to a state that would require major work to remedy the problems. Other items that require inspection at intervals more frequent than prescribed for calendar inspections are also included on the daily inspection, and thus are done along with the daily inspection on the day they become due. Conditional inspection. Conditional maintenance requirements are unscheduled events required as the result of a specific overlimit condition, or as a result of circumstances or events that create an administrative requirement for an inspection. A logbook entry is required for a conditional maintenance requirement that prescribes inspections to determine equipment condition; for example, airframe hard landing, precarrier/predeployment, aircraft ferry, acceptance/transfer, or engine overspeed/overtemp inspections. Those conditional requirements that specify servicing or fluid sampling need not be logged. Preflight inspection. The preflight inspection consists of checking the aircraft for flight readiness by performing visual examinations and operational tests to discover defects and maladjustments that, if not corrected, would cause accidents or aborted missions. This inspection is conducted before each flight to ensure the integrity of the aircraft for flight and to verify proper servicing. It is valid for a period of 24 hours, provided no flight and no maintenance other than servicing occurs during this period. When all preflight requirements are contained within the daily card set, accomplishment of the daily requirements before the first flight of the day satisfies the preflight inspection requirements. When all preflight requirements are not included in the daily card set, the preflight inspection must be performed before flight. The application statement contained on the applicable model weapons system MRC introduction card states specific requirements. Postflight inspection. The postflight inspection is accomplished after each flight or ground operation of the aircraft. The postflight inspection is mainly a check for obvious defects (hydraulic, fuel, and oil leakage or structural damage) and the installation of the necessary safety locks and pins. Turnaround inspection. Turnaround inspections are conducted between flights to ensure the integrity 5-32

of the aircraft for flight, verify proper servicing, and to detect degradation that may have occurred during the previous flight. The turnaround inspection is valid for a period of 24 hours, provided that no flight and no maintenance other than servicing occur during this period. The accomplishment of the daily inspection does not satisfy the turnaround requirements. On aircraft that are furnished turnaround inspection requirements, the preflight and postflight requirements do not apply. Phase inspection. The phase maintenance concept divides the total scheduled maintenance requirements into small packages or phases of approximately the same work content. These are done sequentially at specified intervals. Completion of all required phases at their specified intervals completes the phase inspection cycle. The cycle is repetitive for the service life of the aircraft and is not interrupted during SDLM. Phase inspections are not included in the SDLM specifications, and are not done during the SDLM process. Aircraft returning from SDLM/special rework have the next phase due upon expiration of the authorized interval from the last phase inspection completed. Special inspection. A special inspection is a scheduled inspection with a prescribed interval other than daily or phase. These intervals are specified in the applicable PMS publication and are based on elapsed calendartime, flight hours, operating hours, or number of cycles/events; for example, 7, 28 days; 50, 100, 200 hours; 10, 100 arrestments; or 5,000 rounds fired. Zonal inspection. A zonal inspection is a general inspection of a specific area of an aircraft. These inspections are for obvious defects, such as leaks, frayed cables, cracks, corrosion, or physical damage. Zonal inspections are normally performed in conjunction with other scheduled maintenance tasks by the rating assigned, such as an Aviation Electronics Technician (AT) rating assigned to perform an inspection on a radar antenna may also be assigned a zonal inspection of the compartment for obvious defects. NOTE: You should refer to the Naval Aviation Maintenance Program (NAMP), OPNAVINST 4790.2, for added information about the maintenance program and the forms and records used in the program. Q43. Q44. Q45. Q46. Q47. Q48. What type inspection is performed at the time a reporting custodian accepts a newly assigned aircraft? What type inspection is performed to check equipment that requires a daily verification of satisfactory functioning. What type inspection is required as the result of a specific overlimit condition? A preflight inspection is valid for a period of how many hours? What type inspection consists of checking the aircraft for fright readiness by performing visual examinations and operational tests to discover defects and maladjustments that, if not corrected, would cause accidents or aborted missions? What type inspections are normally performed in conjunction with other scheduled maintenance tasks by the rating assigned? SUMMARY This chapter identified the organization of the line division. Responsibilities and qualification of a plane captain were covered but were not all inclusive. Special safety requirements and safety precautions for aircraft ashore and afloat were also mentioned. Special programs covered in this chapter touch on the basics. The information contained in these programs is more than any individual could be expected to memorize or be solely responsible for. You should keep informed of changes to programs at your command that might affect your work center. 5-33

ANSWERS TO REVIEW QUESTIONS A1. Maintenance department. A2. The Support Equipment Branch. A3. The Plane Captain Branch. A4. The commanding officer. A5. 100 feet. A6. Nonsparking tools. A7. Aft center body, upper speed brake, directly aft of overwing fairings and directly behind the canopy. A8. The wind may carry fuel vapors toward a source of ignition. A9. Three. A10. Identify the aviation fuel. A11. Pressure fueling gives aircraft a faster turnaround time. A12. The appropriate aircrafr Maintenance Instruction Manuals (MIMs) and the Aircraft Refueling NATOPS Manual, NAVAIR 00-80T-109. A13. The internal fluid resistance to flow caused by molecular attraction. A14. The Saybolt scale. A15. MIL-H-83282. A16. It should be properly disposed of immediately. A17. Daily. A18. This prevents the operator from being struck by debris if the tire were to fail. A19. The wheel halves may separate when the axle nut is removed. A20. AME rating. A21. It is used to service struts, accumulators, air storage bottles, and other components serviced with high-pressure air. A22. It removes moisture that may have adhered to the valves or that was accidentally introduced into the system. A23. 3 gallons. 2 gallons in the unit reservoir and 1 gallon in the can. A24. The flight deck. A25. Only when actually performing maintenance on the propeller. A26. No! Serious injury can still result by being pulled against the protective screen. A27. High temperature and high velocity of exhaust gases. A28. 140 decibels (dB). A29. Ejection seats. A30. The area on both sides of the tire and wheel, in line with the axle. 5-34

A31. CO2. A32. LOX can explode when it comes in contact with oil or grease. A33. Limited space and tempo of operations. A34. Command support, personnel knowledge and awareness, and its integration into the total maintenance effort. A35. The material control officer. A36. Saving lives and equipment by eliminating tool FOD-related accidents. A37. To maintain a satisfactory level of fluid purity in hydraulic systems to provide safe and efficient operation of naval aircraft and SE. A38. The Aircraft Refueling NATOPS Manual, NAVAIR 00-80T-109. A39. 90 days. A40. Navy Occupational Saftey and Health Program Manual, OPNAVINST 5100.23. A41. The assistant aircraft maintenance officer (AAMO). A42. Anyone witnessing the misuse or abuse. A43. Acceptance inspection. A44. Daily inspection. A45. Conditional inspection. A46. 24 hours, provided no flight and no maintenance have occurred during this period. A47. Preflight inspection. A48. Zonal inspections. 5-35

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CHAPTER 6 WORK CENTER MANAGEMENT AND QUALITY ASSURANCE To most personnel, an assignment to a supervisory position is a welcome challenge. They like the feeling of the added prestige, authority, and the responsibility that accompanies the assignment. However, when you do reach this level, you may soon realize that the position of Work Center Supervisor is not as easy as it may have seemed when viewed from another position. Each day you may be confronted with many new problems and situations that require immediate action. If you know the duties, responsibilities, personnel, equipment, tools, and job priorities, it will be easier to function in a supervisory capacity. However, if you don’t possess this knowledge, your troubles may multiply at an alarming rate. A supervisor sets in motion the plans, schedules, and policies of his superiors. When you become a supervisor, you are primarily concerned with seeing that the job is done correctly, safely, and efficiently with no waste of materials. You will not necessarily perform the work yourself. You must know your personnel, know their limitations, assign them the work to be done, train them to do the best job possible, and, if necessary, direct them through the performance of the work. YOU assume the responsibility for seeing that the job is done, and done right. This role demands skill, common sense, and mutual respect. OBJECTIVES OF THE WORK CENTER SUPERVISOR The first part of this chapter will discuss some of A specific list of duties and responsibilities can the general duties and responsibilities of a supervisor be made concerning only a specific position. and a few ways to prevent some problems before they However, listed below are some typical duties and are problems. responsibilities common to all work center supervisors: THE WORK CENTER SUPERVISOR LEARNING OBJECTIVES: Describe the primary concerns of the work center supervisor. Describe how the work center layout affects efficiency and safety. To be a supervisor, you must clearly understand the terms supervision and supervisor. SUPERVISION can be defined as the act of guiding, directing, overseeing, evaluating, and controlling the activities of others in the accomplishment of an objective. A SUPERVISOR can be defined as the one who is responsible for and directs the work of others. Get the right person on the job at the right time Use and place materials economically Ensure personnel and equipment safety Promote high morale Maintain quality work Keep accurate records and reports Maintain discipline within the work center Plan and schedule work Train personnel Procure the proper tools and equipment to do the work THE SUPERVISORY POSITION Inspect, preserve, and protect tools and equipment The job of supervising your personnel in a work center is a many sided task. Some of the techniques are learned through past experience; others will be learned during actual supervision. Still other techniques may be learned from self-study courses and technical publications. Give clear orders and directions Maintain liaison with other work centers Check and inspect jobs and workmanship Promote teamwork Maintain good housekeeping 6-1