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Volume 2 Self-Test
Volume 2 CDC Self-Test Questions 2A654
| Question | Answer |
|---|---|
| What are the 3 types of fuselage construction? | 1) Truss 2) Monocoque 3) semi-monocoque |
| In what type of fuselage construction does the skin carry the primary stress load? | Monocoque construction |
| For what purpose was the semi-monocoque type fuselage designed? | To overcome the strength-to-weight ratio problems. |
| What type of material is used in the construction of the semi-monocoque fuselage? | Aluminum alloy |
| Which members of the semi-monocoque fuselage are the longest and strongest?Longerons | Longerons |
| What function do the stringers serve in a semi-monocoque fuselage? | They provide cross-sectional strength to the fuselage and serve as attachment points for the skin. |
| What purpose do the wings serve? | Provide the lifting force for the aircraft as it moves rapidly through the air. |
| What factors determine the design of the aircraft's wings? | Size, weight, airspeed, rate of climb, and aircraft mission |
| What kind of wing design do most military aircraft use? | cantilever |
| What is meant by the term "positive dihedral wing?" | It means the wing angles upward from the fuselage |
| What units or components may be included as part of an aircraft empennage? | Horizontal and/or vertical stabilizers, rudder(s), elevator(s) and trim tabs |
| What is the purpose of the vertical stabilizer? | To maintain the directional stability of an aircraft about its vertical axis and is the attachment point for the rudder. |
| In addition to the primary flight control surfaces, what are two other types of flight control surfaces? | secondary; auxiliary |
| What is the function of primary flight controls? | To control the directional movement about the axis of an aircraft |
| Where are the ailerons located on the aircraft? | On the trailing edge near the wing tips |
| What is the purpose of the rudder? | To control the movement of the aircraft about the vertical axis. |
| What purpose do the trim tabs serve? | Aid the primary flight controls by correcting for any unbalanced condition of the aircraft in flight |
| What are two examples of auxiliary flight controls? | Flaps and spoilers |
| What is the purpose of the aircraft landing gear? | To support the aircraft during landing, resting, or moving about on the ground. |
| Depending on the aircraft, how may the landing gear be extended or retracted? | Via a retraction mechanism that may be electrically, mechanically, or hydraulically actuated. |
| What is the definition of low observable? | A series of processes that give an object the ability to defeat radar, thermal, acoustical, and visual detection. |
| What increases an aircraft's ability to survive? | The ability to defeat various detection methods |
| What major stealth technology advancement occurred in the late 1970s? | The use of advanced composites in the B-1 bomber. |
| What is the main purpose of LO technology? | To increase the survivability of a weapons platform |
| Regarding grip length, what is the ideal installation of a nut and bolt assembly? | A minimum of two threads should be showing through the nut. |
| Normally, how are special bolts identified? | The letter "S" is stamped on their heads |
| What three factors help maintenance personnel identify the size of the bolt? | Length, diameter, and threads per inch |
| Normally, where are hex head bolts used? | Where heavy tension or lengthwise stresses must be sustained |
| What type of bolt is made of high-strength steel, and used primarily in high-tensile, high-fatigue, strength applications? | The 12-point, external-wrenching bolt |
| On an aircraft, where would an eyebolt be used? | Where external tension loads are applied |
| Name the two primary categories of nuts | self locking and non self locking |
| What type of nut requires an external locking device to ensure the nut does not vibrate loose? | Non self locking |
| List three features of the self-locking type nut | (1) It has a locking feature built into the nut, Some have a nylon or fiber insert and It is designed to withstand extreme vibration. |
| How many threads must extend through the fiber of the self-locking nut? | 1 1/2 threads |
| What hardware item is used with screws and bolts whenever the self-locking or castellated nut is not used? | Lock washers |
| What is the most common form of threaded fastener used on aircraft? | screw |
| When would a flathead screw be used? | In countersunk holes where a flush surface is desired. |
| What type of screws is designed for electrical use? | Roundhead screws |
| What is the most common type of rivet used for fastening aircraft structures? | Solid shank rivet |
| From what materials may solid-shank rivets be made? | Generally aluminum alloys but may also be made from corrosion-resistant steel, mild steel, titanium, iron, or copper for special applications. |
| What type of rivets is used in the interior of aircraft where a flush surface is not necessary? | Brazier head rivets |
| What rivets are used on the outside wing structure where a smooth, aerodynamic surface is desired? | Countersunk rivets |
| What type of areas would require the installation of a Jo-bolt? | Where access to one side of the work is impossible |
| What is a hi-lok fastener? | It is a high-strength threaded fastener, which combines the best features of a rivet and a bolt |
| What are some common uses of tubing systems used on aircraft? | To route fuel, oil, coolant, breathing oxygen, hydraulic and vent lines, as well as electrical conduits and ventilation ducts |
| What are the advantages of aluminum alloy tubing when compared with copper tubing? | Aluminum tubing is lighter than copper, can be easily formed, and has better corrosion/fatigue resistance than copper tubing |
| What type of tubing is suitable for use in high-pressure systems? | Corrosion-resistant stainless steel tubing. |
| Normally, where where would aluminum alloy tubing be used on the aircraft? | For general-purpose lines, conduits supporting low fluid pressure, such as instrumental lines and drain lines, sensing lines, any drain lines, and open-type fuel vent manifolds |
| What type of tubing is most widely used for general-purpose applications? | Aluminum alloy tubing |
| What impact would chafing have on a section of manifold? | It would produce a mechanical property change in the metal that would greatly reduce its ability to withstand internal pressure and vibration |
| List four areas on the aircraft are commonly inspected for signs of tubing chafing? | Dry bays, wheel wells, component parts and integral fuel tanks |
| What is the allowable limit for a scratch in a straight section of a pressurized fuel manifold? | no deeper than 15% of the tubing wall thickness |
| At what locations on an aircraft would flexible hose be installed? | Areas where a great amount of vibration occurs or where flexibility is required |
| What are three types of couplings commonly used on aircraft fuel systems? | Quick-disconnect, V-band, and Wiggins. |
| What are the advantages of QD couplings? | Ease and speed of connecting and disconnecting plumbing systems, particularly in congested areas and some QD couplings have self-sealing valves to eliminate fluid or air loss when disconnected |
| What type of V-band coupling requires the installation of safety wire as an added safety measure? | QD V-band couplings. |
| What component of a Wiggins coupling provides the sealing action? | O-rings |
| What type of safety wire is used on aircraft hardware? | Zinc-coated soft steel wire. |
| For which applications would the single wire method normally be used? | On fasteners in a closely spaced or closed geometrical pattern, on electrical parts, and in places difficult to reach |
| When securing widely spaced bolts by the double-twist safetying method, what is the maximum number of bolts that may be wired in a series? | three |
| How many twists of wire does the "pigtail" require? | 3-6 twists |
| When using the double-twist method to secure two bolts, under what conditions would .032-inch safety wire be required? | On fasteners/parts that have a hole diameter larger than .045 inch |
| For what purpose are cotter pins used on aircraft? | To secure bolts, screws, pins, and shafts |
| How would you select the proper diameter cotter pin for a given application? | Select the largest diameter cotter pin that will fit in the drilled hole and/or the slots in the nut, unless otherwise specified in the applicable technical data |
| When properly installed, what surface should the bent prong of a cotter pin not touch? | The surface of the washer |
| Where does the corrosion of metals begin? | On the surface of metals |
| What effect can paint coatings have on initial stages of corrosion? | They can hide initial stages of corrosion |
| List the three degrees of corrosion | light, moderate, severe |
| How is light corrosion identified? | The protective coating is scarred or etched, and the condition of the metal is discolored and pitted to a depth of approximately one millimeter (0.001 inch) maximum. |
| Normally, what type of corrosion is removed by extensive hand sanding or light mechanical sanding? | Moderate corrosion |
| Normally, what type of corrosion is removed by extensive hand sanding or light mechanical sanding? | Moderate corrosion |
| What degree of corrosion is characterized by pitting in depths of more than 10 millimeters? | Severe corrosion |
| How is the damage of severe corrosion removed? | By extensive mechanical sanding or grinding |
| During a routine inspection of a steel cable for a firewall shutoff valve, you discover corrosion on the outside surface of the cable. What is your next step? | Relieve cable tension and carefully force the cable open by reverse twisting. Visually inspect the inside of the cable for signs of corrosion |
| When would attaching parts such as nuts, bolts, screws, and so forth require painting in detail? | Only when dissimilar metal or wood contact is involved in the material being joined |
| What should be done with severely corroded screws, bolts, or washers? | replace them |
| To what type of corrosions are rubber parts susceptible? | Fungus growth |
| What type of coating do you apply to a section of aluminum tubing after cleaning and removing the corrosion? | Conversion coating, MIL-C-81706, Class 1A |
| What is used to protect a stainless-steel engine feed manifold exposed to the outside environment? | The specific exterior finish called for in the applicable TO |
| Name three types of screwdrivers | Common, cross-point, and offset. |
| Why is using the correct size screwdriver so important? | To prolong the life of and to prevent damage of the screw head |
| What two types of hammers were discussed in the text? | Ball-peen and soft-faced mallet |
| Name the striking surfaces of a ball-peen hammer and explain their uses. | The flat striking surface is used for driving punches and chisels, and the rounded surface is used as a peening tool |
| Should pliers be used to tighten fittings? Why or why not? | No; they'll damage the material |
| Name the three most common types of pliers? | Diagonal-cutting, long-nose, and slip-joint |
| What are the uses of the three most common types of pliers? | 1) diagonal - cut safety wire 2) long-nose - reach where fingers can't 3) slip-joint - grip wires |
| Name five hand punches and describe their uses. | 1) Center punch 2) prick punch 3) starting punch 4) drift punch 5) pin punch |
| What tools are used to loosen tight-fitting pins? | A drift punch or starting punch |
| What tools are used to loosen tight-fitting pins? | Open-end, adjustable-jaw, box-end, socket, and Allen wrenches. |
| What tool tightens a Wiggins coupling? | spanner wrench |
| When you are performing work that requires the use of a work stand, how do you carry your tools up on the work stand? | Use tool-carrying bags |
| What do you do with hand tools that you do not expect to use for some time? | Coat tools with lubricant |
| Normally, what do you do with a damaged tool? | Turn it in for replacement |
| What care do you give hand tools that are extremely dirty and grimy? | Clean with an approved cleaning solvent |
| Describe the technique used to torque a loose bolt and compare it to the technique to torque a bolt that is already tight | Keep the nut or screw turning with a steady sweep of the wrench until the specified torque is reached. To retorque a screw or nut, back off the screw or nut so that less-than-specified torque is required to start it turning in the proper direction |
| What type of torque wrench has a preset torque and cannot be adjusted? | T-handle type |
| How do you convert inch-pounds into foot-pounds? | Divide the inch-pounds by 12 |
| What is the result of using an extension or adapter on a torque handle that increases its length? | The predetermined torque will be affected |
| What do you do before using a drill to bore a hole? | Mark the area to be drilled using a center punch |
| What type of power tool may be used to speed the the removal of access door fasteners? | Impact wrenches |
| When using an impact wrench to install access door fasteners, what must you never do? | Never use an impact wrench to apply final torque. |
| What tasks may require the use of a bench grinder? | Sharpening tools, fabricating sealant scrapers, and grinding drill bits. |
| What procedure do you use to check the integrity of a grinding wheel? | Tap the wheel with a plastic or rubber mallet; a ringing sound will indicate a good wheel |
| What two safety precautions must always be observed when using a bench grinder? | 1) ensure that the work rests are in place and correctly adjusted 2) never use a grinder if the wheel guards are missing |
| For what purpose is the pneumatic buffer used? | It is used to buff lightweight fuel cells, and for final buffing work on a fuel cell patch. A heavier buffer is also made for fitting flange repairs and buffing self-sealing cells |
| What is the purpose of the two-part sealant high-pressure injection gun? | To inject two-part sealant into voids, channels, and other areas where a higher pressure is required than can be furnished by the filleting gun |
| What is the ratio of the output pressure of the injection gun to the input pressure? | 50:1 |
| How and when do you clean the gun? | Clean after each use, before the sealant cures, with cleaner rods the same size as the tip orifice using cleaning solvent. |
| Why must you provide a bleed hole for the sealant injection with this gun? | To relieve the pressure between the structural members of the aircraft to prevent damage |
| For what should the sealant-filleting gun be used? | To apply fillet seals |
| What controls the thickness of the fillet during application? | The size of the nozzle orifice |
| What is the purpose of the one-part sealant injection gun? | To inject one-part sealant into channels under the wing skin |
| Explain the operation of the one-part sealant injection gun | Put one-part sealant into the barrel with a spatula while keeping trapped air and foreign matter to a minimum, adjust regulator to the correct air pressure, push the trigger and the piston will move forward and force sealant out of the nozzle. |
| What could happen if the air pressure used to operate the one-part sealant injection gun were too high? | The high air pressure could damage the airframe or cause the gun assembly to explode while you are operating it. |
| What are four precautions to observe concerning the use of pneumatically powered tools? | 1) do not abuse air hoses 2) operate air pressure with the limitation of the tool specification 3) keep compressed air free from all foreign matter and moisture 4) prevent static electricity buildup on tools and personnel |
| Why must air hoses be kept clean? | Because dirt will be carried into the fuel tank if the hose has to be taken inside the tank |
| What do you do to prevent the buildup of static electricity when using a pneumatic tool? | Bond the pneumatic tool and make frequent use of the personnel-static-discharge plate |
| What requirement must lights meet before they can be used for fuel systems maintenance? | NFPA-70 Class 1, Division 1, hazardous areas. |
| Why is it important to keep the bucket as close as possible to the drain? | Keep the fuel from dispersing/spreading out |
| Why should a scraper never be made from brass or steel? | Because it could cause corrosion or damage to the aircraft structure |
| What is the two-fold purpose of the water manometer? | It provides a means of relieving excess positive or negative fuel tank pressure and it is used as a pressure gauge |
| Why must both connections of the water manometer be unplugged? | Because the fuel tank could be over pressurized and cause damage to the aircraft. |
| What items do you inspect before using a water manometer? | Obstructions in the positive and negative connections, Obstructions in manometer hose, Fluid level of manometer, Maximum pressure used and Length of the plastic tube. |
| What atmosphere measuring equipment measures the atmosphere of the fuel tanks? | PID |
| Which button is pressed to turn on the pid? | Mode button |
| When is the PID ready for use? | At the end of the warm up sequence |
| How long should you sample each area of the tank? | For sixty seconds, plus one second for every foot of hose used |
| When inspecting the PID, what is the first thing you should check? | Calibration date |
| What is the purpose of the bonding meter? | To identify the integrity of electrical connections by measuring and displaying small values of resistance (less than 2 ohms) |
| Can the meter be used inside the repair area or facility? Why or why not? | Yes; because the meter is intrinsically safe |
| Which set of test probes should you use when you need to monitor the meter while taking a measurement? | The set consisting of a probe on one end and a clamp on the other |
| Which button turns on the meter display? | test button |
| How does the meter conserve battery power automatically? | A built-in timer automatically shuts off the display after 52 seconds of operation |
| What are the uses of air compressors used in fuel systems maintenance? | Operation of pneumatic tools, blowers, and pumps, as well as for the ground-checking and servicing some aircraft |
| What unit is commonly used to supply air pressure for the operation of pneumatic tools? | MC-2A (low-pac) |
| What is the maximum pressure available from the MC-2A air compressor? | 200 psi |
| Briefly describe the MC-7 air compressor | It is a Diesel engine-driven rotary air compressor, which is capable of producing 125 cfm of airflow at a maximum of 100 psi. |
| What are the four safety precautions discussed in the text that you always follow when using any air compressor? | 1) keep the housing side doors closed during operation 2) follow operating instructions on the unit 3) set the parking brake 4) wear ear pro when unit is operating |
| For what is the explosion-proof pneumatic vacuum used? | For depuddling residual fuel that will not drain during normal drain procedures |
| Which part of the vacuum is not allowed to be modified? | hose |
| What must be done to the vacuum after use? | It needs to be emptied |
| At present, what are the two heaters authorized for use inside the fuel systems repair area? | HDU-13/M heater and the RCD |
| What are the safety features incorporated into the HDU-13/M heater that make the unit explosion-proof? | Exterior panels are made of non-sparking aluminum, the electrical circuitry is encased in an explosion-proof steel box, and the heater is completely sealed, making it explosion-proof |
| For what purposes is the HDU-13/ mainly used? | To provide heated air of ventilating air for purging fuel tanks or cells and to cure sealant and coatings |
| What is the operating temperature range of the HDU-13/M? | 40 to 200°F |
| How do you start the HDU-13/M if you were to use it for curing sealant inside a fuel tank? | Hold both the blower start switch and the heater start switch for 4 seconds, and then press the heater start switch a second time. |
| What heater is not explosion proof and must remain outside the repair area? | HDU-43, new generation heater |
| On the 12-inch fan, what varies the airflow output? | A regulator on the fan |
| When using a pneumatic powered blower, what is the maximum pressure the unit is regulated to if it is to be used for more than three hours? | 22 psi |
| How would you ensure a pneumatic blower is adequately lubricated? | Add 1/2 ounce of 10-weight oil after every days use |
| What type of air conditioners, if any, should be used inside the repair area for ventilating a fuel tank? | Air conditioners are not explosion-proof and are not authorized inside the repair area. |
| What system is installed in new facilities and can be used for purging fuel tanks? | Climate control unit |
| What equipment must be used to supply air pressure to a fuel cell/tank servicing cart? | An air compressor, such as an MC-1A or MC-7 |
| What safety feature of the fuel cell/tank servicing cart supplies breathing air to workers inside a fuel tank in the event of an air compressor failure? | An emergency breathing air supply bottle incorporated in the servicing cart |
| It is a portable, oil less, pneumatic- powered pump that supplies low-pressure ambient air for up to three respirators at once. | |
| Where is the snorkel of the ambient breathing air pump placed? | In a fresh air area free from fumes |
| What minimum length of air hose is required from the air pump to the respirators? | 50 feet |
| What is the only component on the breathing air pump that may be modified? | The inlet filter extension |
| What purpose does the nitrogen cart serve? | Supplies nitrogen to a fuel system when inerting is required |
| What support equipment item furnishes lighting during hours of darkness? | Portable floodlight set (light-all) |
| For what other purpose can the unit in the previous question be used? | As a power source for equipment such as a sealant mixer or droplight. |
| What is the purpose of a typical diesel generator? | To provide 400 hertz, 115/200 volt, three-phase power to an aircraft for the operation of the aircraft's electrical equipment when the onboard generators are not running |
| Which generator is a jet engine and requires double hearing protection? | The A/M32A-60 gas turbine generator |
| How do you know if the diesel generator has been properly connected to the aircraft and is operating sufficiently to generate voltage? | An indicator light inside the aircraft illuminates |
| Which maintenance stand would you use if you needed the platform height to reach 3 feet? | B-1 stand |
| Which maintenance stand has an adjustable height from 13 to 20 feet? | B-2 stand |
| Which scissors-type maintenance platform can be adjusted from 7 to 12 feet? | B-5 stand |
| What safety feature is used on some maintenance stands to prevent the platform from lowering in case of hydraulic system failure? | safety lock |
| What items are installed on maintenance stands or platforms when they are used specifically for fuel systems maintenance? | Static discharge plates and bonding wire reels |
| What is a circuit? | a complete path through which electricity can flow |
| Define "current" | The flow of electrons through a conductor |
| What term is defined as the force required to push one ampere of current past a given point in one second? | volt |
| What term is defined as the opposition to current flow? | resistance |
| List the five basic parts/functions of a circuit | 1) power source 2) load device 3) conductor 4) control device 5) protective device |
| List three potential power sources for an aircraft electrical circuit | Battery, external power unit, generator |
| How many different types of resistors are there? Name them | 2; Fixed and adjustable. |
| What component in a circuit allows current to flow through it in only one direction? | Diode |
| What component, used in a circuit, protects the circuit from excessive current flow? | circuit breaker |
| Explain the basic operating principle of a relay | When power is applied to the coil, an electromagnetic field attracts the moveable armature and pulls it toward the coil. When the armature moves, the contacts either open or close |
| What is the most common use of solenoids in a fuel systems electrical circuit? | manually control a fuel level control valve |
| What type of toggle switch can complete two individual electrical circuits, but only one circuit at a time? | SPDT switch |
| What is the purpose of cannon plugs? | They provide a means of quickly connecting and disconnecting wires to simplify installation and maintenance. |
| How are the pins marked on cannon plugs? | With letters, starting alphabetically, with capital letters, then alphabetically with small or lowercase letters and then double capital letters |
| Name the four functional areas of the typical digit multimeter | 1) digital display 2) annunciators 3) bar graph display 4) range indicator |
| What should the meter indicate if the circuit being measured is higher than the range selected? | OL (overload) |
| What part of the multimeter provides information about battery condition and operating mode? | Annunciators |
| In which position must the multimeter be placed to turn the meter on? | Any position other than any of the two OFF positions |
| How is the auto-range mode selected? | It automatically defaults to the auto-range mode when the meter is turned on. |
| How are the meter test leads connected in the circuit when measuring voltage? | They must be placed in parallel with the circuit being measured |
| What is the most important thing to remember when measuring resistance in a circuit? | Ensure power is not applied to the circuit |
| Regardless of the type of aircraft, what must you always use to troubleshoot an aircraft electrical system malfunction? | Technical Data |
| What function would you set your multimeter to when taking a resistance reading as part of the troubleshooting process? | To the ohms function |
| Explain how you would connect the multimeter test leads when checking the pins of a cannon plug for AC power | Set the multimeter to the AC voltage function setting, ensure the red test lead is plugged into the red VOLTS/OHMS jack and the black lead is plugged into the COM |
| What are three requirements that all fuel system repair facilities and areas must meet? | They must be kept clean, be maintained in good repair, and remained off limits to nonessential personnel |
| Who ensures that operating instructions are available for each equipment item installed in a fuel systems repair facility? | MXG/CC |
| What is one difference between the emergency shower and eyewash requirements in a new facility as opposed to those of an existing facility? | A new facility requires a privacy enclosure. |
| In a new or existing facility, a requirement exists for a positive pressurization system in the break room, office, support room, and restrooms; what is the purpose of this system? | To prevent fumes and vapors from migrating from the aircraft repair area |
| Besides the requirements listed for the new and existing facility, name two additional requirements when working in temporary facility. | Drain all aircraft fuel tanks and defuel before the aircraft enters the facility, and adjoining offices should be isolated or evacuated during fuel system maintenance |
| What are the requirements for the positioning of exhaust purging ducts when you are working in a temporary repair facility? | Position the ducts outside the facility doors, and position them to prevent fuel fumes from traveling back into the facility |
| What requirement must portable electrical equipment meet if used in an open fuel systems repair area? | They must meet the requirements of the National Electrical Code for Class I, division 1 hazardous locations |
| When should supervisors conduct a safety inspection of a fuel systems repair facility or area? | At the beginning of each shift |
| Which items on the aircraft should be tagged with an AF Form 1492? | Aircraft external power receptacle, fuel control panel, and single point receptacle |
| What must you do with the aircraft batteries as part of the aircraft preparation checklist? | Ensure they are disconnected in accordance with the applicable aircraft TO and tagged with AF Form 1492 |
| What is your responsibility regarding support equipment used inside the repair area? | Ensure it is serviceable, properly positioned and bonded/grounded to the aircraft if required |
| Aircraft shall not be allowed to operate within how many feet on an open fuel systems repair area? | Within 100 feet |
| Who approves hot work in an aircraft fuel tank? | Fire protection services |
| What are the allowable entry safe levels for hot work? | 90 ppm or 1.5 percent LEL |
| What are five examples of "hot work"? | 1) cutting 2) grinding 3) welding 4) solderizing 5) brazing |
| What portion of the AFTO Form 1492 will be put in the AFTO Form 781A? | Part B, the bottom portion below the perforation |
| What type of hand-held radio used for emergency communication is authorized inside the repair area? | Intrinsically safe radios only |
| Unless otherwise specified in an aircraft TO, what is the minimum distance that must be maintained between full-powered aircraft radar and a fuel systems repair area? | 300 feet |
| Senior Airman Rose is about to install a cover plate on an aircraft fuel tank. What safety item must also be installed? | A red REMOVE BEFORE FLIGHT safety streamer |
| When should an AF Form 1492 be used to flag a vent plug installed on an aircraft? | Only when a yellow REMOVE BEFORE FUELING/DEFUELING streamer is not available |
| What is the primary purpose of roping off a fuel systems repair facility? | To control foot traffic into the facility |
| What is required of rolling support equipment before it may be used inside a repair area? | It must be equipped with antistatic, nonmetal wheels, and inspected prior to bringing into the area. |
| Why is it important to inventory support equipment used in a repair area? | To ensure that no equipment is left on or in the aircraft during fueling, defueling, or flight. |
| When setting up an open repair area, where should you position powered-support equipment? | Outside the 50-foot marked area and upwind if possible |
| What equipment is authorized for use inside the open repair area? | The HDU-13/M heater, explosion-proof fans and blowers, air purifier cart or any other explosion-proof and intrinsically safe equipment |
| Before using a maintenance stand inside a fuel systems repair facility or area, for what should you inspect the stand? | Inspect the step surface to ensure it is not worn and ensure the stand is equipped with a static discharge plate and bonding wires |
| How should tools be brought to the aircraft? | Hand carried in nonmetallic containers, such as fiber-board boxes or canvas bags |
| Who authorizes the issue of a MEP? | Logistics group commander MXG/CC or equivalent |
| Normally, who serves as the entry authority for all confined space entries? | Fuel systems section chief |
| Who has the overall responsibility for terminating an entry in the event of unsafe conditions? | attendant |
| List the duties of the equipment monitor/runner. | Monitors essential fuel entry support equipment, notifies immediately the attendant if a hazard develops or support equipment inoperative, summons rescue team, acts as member of first team rescue, performs duties of attendant, monitors repair areas |
| Which office would you utilize for information on personal protective equipment? | BEF |
| Which office is the wing focal point for confined space issues? | safety |
| What should the BEF, safety, and the fire protection services all do? | Provide training on subject matter for which they have expertise |
| When developing a written emergency response plan for your fuel shop, with whom must you coordinate? | MXG/CC, fire protection services, safety, and BEF officials |
| In the event an entrant becomes unable to get himself or herself out of a fuel tank, what is the first step the attendant must take? | Alerts the runner and ensures the tank is being properly ventilated |
| Under what conditions may an attendant enter the tank to rescue an incapacitated entrant? | If authorized by the emergency response plan but not until the runner assumes the duties of the attendant |
| What training requirement must attendants and equipment monitor/runners satisfy in order to enter a tank to remove an incapacitated entrant? | Trained in CPR and self-aid buddy care or its equivalent. |
| What factor determines the size of the rescue team outlined in the emergency response plan? | The size of the rescue team must be sufficient to ensure that no unattended rescue activity occurs |
| As a minimum, how often must the emergency response plan be exercised? | At least once a year |
| For what maximum time may a MEP be issued? | 1 year |
| On the MEP, what is authorized by name and position? | Entry authority and designated alternate |
| What must you do to the entry permit if new personnel require entry to the tank? | Amend or reissue the entry permit |
| The entry authority or designated alternate will not authorize any entry that is not consistent with what? | MEP |
| What action must be taken by the entry authority if conditions of the permit change prior to task completion, and the new conditions are consistent with entry permit plan? | They must amend or reissue the entry permit |
| Where must the entry permit be maintained during task maintenance? | job site |
| What should be done with the entry permit after task completion? | Each completed permit, including those that are canceled or revoked, shall be retained for 1 year by the organization responsible for the entry and be available for review. |
| What is the purpose of purging a fuel tank or cell? | To remove volatile fuel vapors from a fuel tank or cell and reduce the LEL of the atmosphere while retaining an acceptable percentage of oxygen in the tank |
| How should approved fuel collection containers, such as bowsers, be identified? | They must be marked to denote the grade of fuel contained within |
| Why would aircraft using JP-5 or JP-8 not require purging? | Because the LEL can be maintained at acceptable levels by simply ventilating the tank |
| What is the difference between air purging and ventilation? | Air purging is accomplished to make the tank fire-safe and entry-safe. Ventilating is the process of supplying fresh air to an entrant once the tank is considered acceptably purged |
| What is considered an "entry-safe" atmospheric condition in a fuel tank containing foam? | 20 percent LEL |
| The PID is the meter of choice. During tank entry, where must the PID be located? | It must stay turned on and in the vicinity of the entrant at all times |
| How often must you record a reading during normal tank entry? | Every 4 hours and record on the entry permit |
| During foam removal, how often must you take and record the tank atmosphere? | Every 15 minutes |
| What air purge method is the preferred method? | Combination purge |
| During preparation for blow purging, what step must be taken immediately before removing the access door? | Start the air mover and blower, and bond the air ducts to the aircraft |
| What should you do if the blower motor begins to malfunction during a blow purging operation? | Immediately remove the air duct from the aircraft and move the blower and duct to an area free of fuel fumes, vapors, then turn the blower off |
| After blow purging a fuel tank for the initial 30 minutes, you check the LEL. What should be done next if the LEL is above 20 percent? | Purge the tank for an additional 15 minutes and recheck the LEL |
| How often must a LEL check be made of aircraft containing foam? | Take reading every 15 minutes or more often as deemed necessary |
| Which type of purging results in a less toxic atmosphere in a shorter time? | Combination purge |
| What procedure supplies fresh air to a tank once it is fire safe? | ventilation |
| Why is explosion-suppression foam used in some aircraft fuel tanks? | To suppress explosive reactions, control the rate of burning fuel vapors, and act as a baffle to limit fuel sloshing |
| What safety equipment must you wear when removing foam from a fuel tank or cell? | Chemical resistant gloves |
| What is foam inspected for after removal? | Legibility of marking; cleanliness or contamination; burning or singeing; deterioration; and tears and punctures |
| How should foam be stored in a hangar? | It should be placed in a clean, electro-static free plastic or canvas bag, or placed on a clean, electro-static free plastic or canvas ground cloth, and cover it with clean electro-static free plastic or canvas |
| When storing foam outside, from what elements should it be protected? | Particulate contamination, direct sunlight, and water |
| If necessary, what tools are used to cut foam pieces? | A sharp electric knife, Ontario knife, or band saw with self-cleaning blade |
| What must occur if more than 25 percent of the foam in a fuel tank has been replaced? | You may need to flush and test the system, and take fuel samples |
| What is the purpose of deppudling a fuel tank or cell? | To remove fuel located in low places in the tank so that maintenance can be performed |
| What equipment is used for depuddling a fuel tank or cell? | To remove fuel located in low places in the tank so that maintenance can be performed |
| What equipment is used for depuddling? | Absorbent cloths, sponges, mops, and approved safety containers or vacuum |
| What safety equipment must be worn when depuddling? | Chemical-resistant gloves and a full-faced, supplied-air respirator |
| What advantage does an integral tank have over a fuel cell? | Greater fuel containment with a decrease in weight. |
| What are the primary structural members of an integral tank? | Spars, ribs, and skin |
| Which structural members form the end boundaries of the fuel tank? | ribs |
| What purpose do the stringers serve? | provide attachment points for the skin |
| Which components aid in strengthening the spars? | stiffeners |
| What are four approved methods to locate a fuel-leak exit point? | Leak-detection powder, Torn paper, Pressure test, Gas detection methods. |
| Why is it important to strip exterior sealants from seams in the suspected leak area as the first step in locating a fuel-leak exit point? | Because fuel may be exiting the structure and traveling along the inside of the seam until it finds an opening, which is not the exact leak exit point |
| What is the maximum air pressure used to blow out seams when using the torn paper method? | 30 psi |
| What provides a visual indication of a fuel leak when using the torn paper method? | The fuzzy edge of the paper will absorb the fuel |
| The pressure-test method of leak localization is considered effective for which situations? | Locating leaks that appear only under stress, locating in-flight leaks, confirming a repair prior to refueling, and locating multiple leaks in a tank |
| What safety requirements must be followed when performing the pressure-test method? | A water manometer must be used as a pressure limiting device, entries must be made on the aircraft forms, and a checklist must be used to ensure all plugs, cover plates, and caps are removed when the test is complete. |
| How long should leak-detection compound be allowed to remain on the aircraft? | no longer than 24 hours |
| When locating a fuel leak near a common tank boundary, which tank should you defuel/transfer first? | The outboard tank |
| At what point is classification of a fuel leak performed? | Immediately after locating the exit point. |
| What maximum air pressure may be used to dry the leak area during leak classification? | 30 psi |
| What should you do when in doubt as to the category of a fuel leak? | Classify the leak to the next higher leak category |
| What are two examples of internal vented areas on an aircraft? | Front and rear spars and ventilated dry bays |
| What action is required for a condition 1 fuel leak? | Document the leak and periodically inspect it for growth to condition 2 or 3. No repair is necessary. |
| If a fuel leak with a condition 3 cannot immediately be repaired, what action must you take? | The aircraft is grounded until the leak is returned to a condition 1 or 2 or is permanently repaired. |
| On what forms must all integral tank fuel leaks be documented? | AFTO Form 781A or 781K, and AFTO Form 427 or 428 |
| What is the purpose of a leak path analysis? | To determine how fuel in an integral tank leaks to the outside. |
| What are the three elements of a leak path analysis? | Source, path, and exit point |
| What is the seal plane? | The barrier, which contains the fuel in a tank, composed of elements such as the structure, sealant, seals, gaskets, and fasteners |
| What effect may a seal plane penetration have on leak path analysis? | If this seal plane is penetrated, fuel will enter a part of the structure that may not be designed to contain fuel. This may allow fuel to exit the aircraft several feet from the leak source. |
| When using structural and sealing technical manuals to study the aircraft structure in the suspected leak area, what procedure may help to trace all potential leak paths? | Construct cross-sectional views of the structure |
| What procedure should be used to check sealant for adhesion? | Apply air pressure at a maximum of 100 psi, keeping the nozzle approximately 1 inch from the sealant |
| How is sealant checked for loss of elasticity? | By firmly pressing the sealant with a blunt metal punch - not smaller than 3/16 inch diameter. If the sealant is serviceable, it returns to its original position; if it is defective, the punch penetrates the sealant |
| What are the authorized leak-source isolation methods in order of ease of performance? | Blowback, pressure box, leakage-tracing device |
| What leak-source isolation method involves directing compressed air at the leak exit point and applying leak-detection compound inside the tank? | The blowback method |
| What types of dye are used with the leakage-tracing device? | Red or fluorescent dye |
| What accessories are used with the leakage-tracing device? | Double-cup assembly, hollow-bolt dye injector, vacuum dye, vacuum cup, and pressure box |
| What is the purpose of the double-cup assembly? | To locate leak sources by forcing dye solution through the leak exit point |
| When would the hollow bolt be useful? | When the double-cup assembly was unsuccessful in finding the leak source |
| Briefly explain the pressure box method of leak-source isolation | The air pressure forces dye back through the leak path and into the tank |
| In what situation would the pressure box be useful? | When trying to locate seep-type leaks |
| When would the vacuum dye method be used? | When all other methods of isolating a leak source have failed - as a last resort |
| What are the three categories of sealant? | Curing, non-curing, and structural adhesive sealants |
| What must be mixed together in order for sealant to begin to cure? | Base material and an accelerator |
| What is the tack-free time of sealant? | The time required for a sealant to cure to the point at which the outer surface will not stick to a plastic film. |
| What type of sealant has been developed for use in voids or channels that cannot be reached? | Non-curing-type sealants |
| How is structural adhesive sealant cure? | It is cured with heat but remains flexible |
| What are the two basic types of integral tank-access doors? | Plug and direct seal |
| What is the difference between the two types of doors? | The plug door opens into the tank; the direct-seal door opens to the outside and the fasteners provide the clamping force to seal the door. |
| Which type of access door seal is the easiest to locally manufacture and install? | Flat gasket seal |
| What are the disadvantages of an O-ring seal access door? | The O-ring may be incorrectly installed, are difficult to install around corners and bends, and are not reusable. |
| What are the advantages of a molded-in-place access door seal? | They generally provide a good seal and are reusable |
| Which type of access door seal requires the application of a parting agent between mating surfaces and requires instillation of the door prior to sealant cure? | Formed-in-place seal |
| How does a self-sealing fastener seal the hole? | By swelling when installed or interference fit |
| How are non-self-sealing fasteners sealed? | With dome nuts, sealing washers, O-rings, sealant overcoats, machine fittings, and sealant channel |
| How much sealant should be replaced during tank maintenance? | Only the sealant that is defective. |
| What is done to the ends of a fillet seal repair? | They are cut at a 45-degree angle and abraded at least 1/2 inch |
| When removing sealant in close, cramped quarters, why should you brace yourself against some type of support? | To avoid injuring yourself if the cutting tool slips |
| What should be used to protect the bottom of the tank from foreign object damage? | Barrier material or wiping cloths |
| What is used to remove small chips and fragments of old sealant from a fuel tank? | vacuum cleaner |
| What material must be applied to exposed cadmium plated fasteners before applying adhesion promoter and sealant? | Either EC1945 or MIL-C-27725 |
| Why shouldn't you touch a cleaned surface? | Because the oils in your skin or perspiration can prevent a good bond between the metal and the new sealant |
| How long should you allow adhesion promoter to dry before applying sealant? | At least 30 minutes, but not more than 24 hours. |
| How large should a typical sealant brush coat be? | 0.10 inch wider than the fillet on either side of the seam |
| How would you apply a fillet sealant brush coat? | Use a brush to work the sealant into and around crevices, holes, seams, fasteners, and on the surfaces to be sealed |
| Why should all air bubbles in a fillet be removed? | To ensure a leak-free service life of the repair |
| What type of equipment is used to repair an injection sealant? | An injection gun |
| What qualities constitute a non-curing sealant design? | A variety of grooves and channels filled with a continuous bead of non-curing sealant |
| What happens when a void or gap develops in the sealant channel? | A fuel leak will appear |
| How far apart are non-curing injection holes normally spaced? | 3-6 inches |
| What action should you take when the sealant is too cold to flow? | Heat the structure with heating pads in the area of the groove |
| Beige using liquid-type sealant, you should visually inspect it for what? | To ensure the lid seals have not been broken |
| What material should you use to determine if sealant has become tack-free? | Polyethylene plastic film |
| What should be the condition of sealant after the cure time has elapsed? | The sealant should be firm but flexible |
| If outdated sealant is tested and has been determined to be serviceable, how long may its shelf life be extended? | It may be extended for three months from the test date |
| What should you do when a particular temporary repair method repeatedly fails to stop the leak? | Make a permanent repair. |
| What must be done to temporary repairs that are made during PDM? | They must be removed and replaced with permanent repairs before release of the aircraft to the using organization. |
| How many temporary repairs, if any, may remain on an aircraft if they were accomplished during the delivery preparation phase of depot maintenance? | A maximum of one per tank |
| Under what conditions should temporary repairs never be used? | To mask or repair leaks caused by structural damage, corrosion, or component failure. |
| What are the approved temporary repair methods, in order of preference? | Hardman extra fast setting epoxy with aluminum-foil patch, aluminum-foil patch bonded with sealant, epoxy tabs, click patch, sealant without aluminum-foil patch |
| What are the temperature limitations of a repair made with Hardman epoxy? | The temperature must be 40 to 120 F |
| What effect will heat have on this type of repair material? | Heat will cause the epoxy to become brittle. |
| When removing a temporary repair done with Hardman epoxy, what are the minimum and maximum temperatures for the heat gun? | Minimum 200 F , Maximum 250 F |
| What tool should you use to pry the patch up? | Plastic scraper |
| How can you improve the results of the cure time when the temperature is below 50 F when using the aluminum-foil patch bonded with sealant? | Preheat the area around the fastener for a few minutes |
| What sealants may be used for the aluminum foil patch repair method? | Class B sealant |
| What are the temperature limitations for using epoxy tabs? | There are no temperature limitations. |
| What can be done to improve adhesion of epoxy tab material? | Scuff sanding the repair area |
| What should be done to the edges of an epoxy tab repair? | They should be feathered approximately 1/4 inch beyond the edge of fastener |
| How should you remove an epoxy tab repair? | Place a plastic scraper at the edge of the repair and tap the scraper with a rubber mallet until the repair pops off. |
| Using the comp air injector kit, how is a temporary repair made? | Use compressed air to force sealant into a flush-type fastener, aluminum foil is placed over the fastener head, and a heating iron is applied to the tape for 5 to 10 minutes to cure the sealant |
| What is the advantage of the comp air injection kit type of repair? | The aircraft does not need to be defueled. |
| What are the three advantages of using an Oyltite Stik for a temporary repair? | 1) Defuel is not required 2) No temperature limitations 3) an immediate cure time |
| What are the three types of fuel cells used on an aircraft? | 1) Self-sealing 2) Bladder 3) Combination |
| What are the four primary layers in a self-sealing cell? | Inner liner, nylon barrier, sealant, and retainer. |
| Which cell layer actually contains the fuel? | Nylon barrier |
| Which cell layer protects the nylon barrier from external activation? | retainerHow long must the outside lacquer coating of a self-sealing cell remain fuel resistant? |
| How long must the outside lacquer coating of a self-sealing cell remain fuel resistant? | 72 hours |
| What are the four types of bladder cells? | Two or more plies of rubber coated fabric, constructed of a combination of rubber coated fabric and buns-ngum, all nylon fabric, polyurethane-coated nylon fabric over an inner liner |
| On a combination cell, where are the self-sealing sections located? | On the bottom and aft sections of the cell. |
| How is a seal made on the rubber face type of fitting? | A seal is made by compression of the rubber faces between the cell and its mating part. |
| What material is applied at a cell factory to prevent drying and cracking of cell material? | plasticizer |
| What danger is presented when the interior walls of a cell begin to crack and check? | The cracking and checking may penetrate through the inner liner and allow fuel to attack the cell structure fabric the next time the cell is used. |
| What can you do to prevent the cracking and checking of a cell interior that has been drained and purged? | Coat the cell interior with a thin coating of oil (MIL-L-6081 or VV-L-825). This may be done by wiping or fogging. |
| When should a cell's interior be covered with a thin coat of oil? | When packaging the cell for storage or shipment, or when the cell is to remain without fuel for more than 72 hours |
| Where should the openings be located when folding a fuel cell? | As far away from folds as possible |
| Before storing a cell, how should you protect it from air, which could dry out the cell? | Put the folded cell in a plastic bag or wrap it in moisture-proof paper with as little air as possible. |
| What should be the temperature of a building used to store cells? | Between 45 to 75 degrees |
| During what times are cells susceptible to damage? | During uncrating, preparation, installation, removal from aircraft, and packing. |
| What temperature should the cell be when you need to fold it? | Below 65 F |
| What should be done with metal fittings that extend from the cell when the cell is out of the cavity? | Place caps on them. |
| What additional protection is given at the folds of bladder cells? | A fiberboard tube |
| Before instillation, what should you do with new bladder cells that have been in storage for more than a year? | Soak them in warm water |
| What is the maximum time that a self-sealing cell may remain collapsed or folded? | 1 hour |
| What is normally the first step in preparing for a fuel cell removal? | Drain, purge, remove foam, and depuddle the cell. |
| When removing more than one cell, in what order should they be removed? | Cells should be removed in order beginning with cell #1 |
| How do you know when a cell has been folded properly in preparation for removal? | The cell should pass through the access door opening without being strained or scraped |
| What do you look for when inspecting the mating surfaces of cell fittings? | Cracks, scratches, distortion, dirt or other damage that could cause a leak |
| What can you do to an O-ring that will not stay in place during the installation of a cell fitting? | Apply a small amount of petrolatum to the O-ring grooved and the O-ring itself |
| How can Vithane cells, which have shrunk, be restored to normal size? | Soak them in warm water (120 degrees F) for 2 to 4 hours |
| What variables make it difficult to develop a predetermined set of troubleshooting procedures when isolating cell leaks? | The grouping of fuel cells, attitudes of the drain surfaces, location of the drain passages, size of the leak, and whether the leak occurs while the aircraft is on the ground or in flight |
| What are two types of cavity-drain systems found on aircraft containing fuel cells? | Common manifold type and individual type. |
| What material can be installed around cell fittings to aid in locating fuel leak origins? | Black leak detection tape. |
| What characteristics of a cell leak normally will indicate the location or origin of the leak? | The severity, location and flight or ground conditions of the aircraft |
| What conditions or defects will likely result in a fast and severe type of fuel cell leak? | A ruptured or cut cell, a loose interconnect fitting, a pinched or distorted O-ring in a cell fitting, or missing O-ring |
| What should you do after locating a cell leak that requires repair? | Inspect the cell for other leaks |
| Which cell defects usually can be repaired on an installed fuel cell? | 1) pinholes 2) inner liner cuts 3) loose supports of hangars 4) blisters 5) loose seams or patches 6) weather-ozone checking |
| Normally, on what factors is cell repair capability based? | Tools, equipment, facilities, skills, frequency of each repair, and mission requirements |
| What types of cell repairs are best performed at depot or contractor facilities? | 1) self-sealing cell repairs 2) repair or replacement of hangars and straps 3) repair or replacement of lacing ferules 4) repair or replacement of fittings 5) corner repairs |
| At what maintenance level are pinholes and blisters in a fuel cell normally repaired? | Field level |
| To what extent can weather-ozone checking be repaired at field level? | Weather-ozone checking requiring a patch measuring less than 12 square inches |
| What conditions warrant the condemnation of a fuel cell? | Self-sealing cell activation that exceeds 200 square inches or extends into a corner or step off area; damage in an awkward location making patch roll down impossible |
| What type of surface must be used for cell inspections? | Clean, smooth, and padded. |
| What are the limits for edge looseness at liner lap for interior cell inspections? | 1/4 inch width if one 1 inch bond is maintained between laps |
| If you do not find a defect with the fuel cell, what are other possible leak sources? | Fittings, O-rings or gaskets |
| What resource should you use to aid in the inspection of a cell? | TO 1-1-3 |
| When doing an exterior inspection on an installed cell, what are you required to inspect? | To what you can see |
| What or how can the exterior of a fuel cell get damaged? | During handling, shipping, testing, and the removal process. |
| List two "not acceptable" conditions concerning exterior cell inspection | Permanent set or crease and damage through the cord or fabric ply |
| What are the two common methods for testing fuel cells? | Soap suds and chemical test. |
| What piece of equipment is used as an air pressure gauge during the soap suds test? | Water manometer |
| What amount of ammonium hydroxide is required to test a cell with a capacity of 1,200 gallons? | 200 cubic centimeters |
| What amount of phenolphthalein crystals is added to 1 gallon of indicator solution? | 15 grams |
| Why do you need to clean all metal surfaces after performing a chemical test? | Prevent corrosion |
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