2A656 VOL 5 Q&A

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  1. Name four symptoms associated with exposure to fire extinguishing agents.
    a. Any four of the following: light-headedness, shortness of breath, headaches, ringing in the ears, nausea, a blue tinge to the skin, frostbite, and death.
  2. How will an insufficient nitrogen charge affect agent discharge?
    a. The cylinder won’t have enough pressure to discharge properly.
  3. If a frangible disc strainer were not installed in the liquid-agent fire extinguisher container, what would be the result when the extinguisher was discharged?
    a. The segments of the ruptured disc would enter the distribution system, where they could obstruct the distribution lines and prevent proper operation of the fire extinguishing system.
  4. What might happen if the time delay relay in the two-shot fire extinguishing system does not operate properly?
    a. The extinguishing agent may discharge into the wrong engine.
  5. In a two-shot liquid-agent fire extinguishing system, which component controls the discharging of the fire bottles?
    a. The cylinder won’t have enough pressure to discharge properly.
  6. What happens when the fire emergency control handle (T-handle) is pulled?
    a. The segments of the ruptured disc would enter the distribution system, where they could obstruct the distribution lines and prevent proper operation of the fire extinguishing system.
  7. What should not be used to test a fire extinguisher squib? Why?
    a. An ohmmeter or multimeter. It could cause the squib to fire.
  8. During operation of a liquid coolant system, the coolant fluid is routed directly through the electronic unit to be cooled. Is this normal operation? Explain.
    a. Yes, the coolant fluid absorbs the heat of the unit as it passes directly through the internal part.
  9. List the characteristics of liquid coolant.
    a. Liquid coolant is nonconductive, noncorrosive, and incompatible with water.
  10. During operation of a liquid coolant system, the liquid coolant is at normal temperatures. How would the temperature be kept from going lower?
    a. The liquid coolant would be bypassed around the heat exchanger by the modulating valve.
  11. How long can you safely run the liquid coolant system in the test position?
    a. Maximum of six and one-half minutes.
  12. Match each liquid coolant system component in column B to its proper function in column A.
    • "Column B" (A)Thermal pilot valve, (B)Solenoid shutoff valve, (C)Delta system bypass valve, (D)Thermal modulating valve.
    • "Column A" d(1)Must be closed by fluid pressure and spring tension to direct the fluid through the heat exchanger, b(2)Is energized closed for the initial three minutes of operation, a(3)Has a bellows that reacts to temperature and pressure changes and will open a valve to bypass the heat exchanger, c(4)Allows excessive coolant pressure to go around an electronic unit and back to the pump.
  13. During system operation, what happens when the temperature of the coolant exceeds 115°F?
    a. The pilot valve closes, which causes the modulating valve to close, so the coolant must flow through the heat exchanger.
  14. What is the procedure to replace the liquid coolant system filter?
    a. Obtain a new element, clean the filter bowl with a clean, soft, dry cloth, put on new packing or a new seal on the bowl, and then reset the pop-up indicator on the filter housing.
  15. What should you do if the ASP indicates a FAILED condition or you suspect contamination of a liquid coolant system?
    a. A rupture disc in the control valve bursts at high pressure.
  16. Why must the servicing unit supply hose be purged before you put coolant into the liquid coolant system?
    a. The wrong size or type could make it impossible to discharge the cylinder.
  17. How is the cable and ball assembly used to release the CO2 from the one-person liferaft’s inflation assembly?
    a. To remove moisture that would ice-up the discharge valve during liferaft inflation.
  18. How is the one-person liferaft’s inflation assembly protected from excessive pressures?
    a. When 250 pounds of CO2 or N2 have passed through them.
  19. Why is it important to use the size and type of wire specified by the TO when safety sealing a life raft inflation cylinder?
    a. By damaging the cylinder threads, then tagging the cylinder as condemned.
  20. Why must all CO2 that is used for inflation pass through two dehydrator filters?
    a. To remove moisture that would ice-up the discharge valve during liferaft inflation.
  21. How often should you replace the dehydration filter cartridge?
    a. When 250 pounds of CO2 or N2 have passed through them.
  22. How should inflation cylinders be made unusable if they have extensive scratches, dents, or other defects that weaken the cylinder wall?
    a. By damaging the cylinder threads, then tagging the cylinder as condemned.
  23. You’re ready to recharge an empty inflation cylinder. You find the weight of the empty cylinder doesn’t match the weight stenciled on its side. What action should you take?
    a. Restencil the cylinder before servicing.
  24. Why is a paper clip or scribe necessary when you’re recharging a one-person inflation cylinder?
    a. To raise the locking spring, this releases the locking sleeve on the valve assembly.
  25. You have attached the charging hose to a one-person liferaft cylinder, laid the assembly on the scale, and started charging the cylinder. Why isn’t actuating of the cam required for free inflow?
    a. The charging pressure compresses the spring that normally holds the check valve in the control head closed, thereby opening the check valve.
  26. What safety step must you take before bleeding pressure from the one-person raft inflation assembly?
    a. Install the diffuser plug.
  27. A one-person liferaft inflation assembly has just been recharged. What must be done before it can be installed on a liferaft?
    a. The inflation cylinder must be leak tested by being submerged in water for 30 minutes under reflected light and then reweighed after 24 hours of storage.
  28. Why must aviator’s breathing oxygen be “bone dry”?
    a. To ensure operation of oxygen system components. Oxygen with high moisture content would freeze at high altitudes, causing the oxygen system to be inoperative.
  29. What effects does a lack of oxygen have on the body?
    a. Blurred vision, shortness of breath, weakness, dizziness, loss of consciousness, and possibly death.
  30. What can cause gaseous oxygen to leak at the filler valve during servicing? How can this problem be corrected?
    a. The retainer locks in the socket handle of the filler valve assembly are not locking on the filler adapter of the servicing hose from the ground service cart. Remove and replace the filler valve.
  31. What construction method prevents high-pressure gaseous oxygen cylinders from shattering?
    a. They’re made of heat-treated alloy and wrapped with steel wire.
  32. How do high-pressure oxygen lines differ from low-pressure oxygen lines?
    a. High-pressure oxygen lines are made of copper alloy with silver solder fittings; low-pressure oxygen lines are made of aluminum alloy with flared fittings.
  33. Explain how the molecular sieve bed operates.
    a. Nitrogen in the air is adsorbed in one bed of molecular sieve while oxygen passes through the bed. When the molecular sieve becomes saturated, the concentrator vents the nitrogen overboard.
  34. What happens if the MSOGS concentrator fails?
    a. It will turn on an OXYGEN caution light in the cockpit and automatically switch to the BOS.
  35. What’s the purpose of the pressure-opening valve?
    a. To prevent the wasting of oxygen that boils off within the container.
  36. How does the warmup coil convert liquid oxygen to gaseous oxygen?
    a. Absorbs heat from the surrounding air causing the liquid oxygen to evaporate.
  37. With what types of oxygen systems can the MD–1 oxygen regulator be used?
    a. With high or low-pressure gaseous or liquid oxygen systems.
  38. How is oxygen increased to the user at an altitude of 30,000 feet by the pressure demand regulator?
    a. The diluter aneroid will close the air inlet valve at 30,000 feet and the user will get 100 percent oxygen.
  39. What’s the purpose of the troop oxygen system?
    a. To supply troops, passengers, or litter patients with oxygen.
  40. What’s the specific use of the bailout bottle?
    a. An independent source of oxygen for emergencies and parachute descents from high altitudes.
  41. How does the capacitance indicating system change its indication as the quantity changes?
    a. As the liquid oxygen level changes, the dielectric value changes and the probe converts this to a signal to the indicator.
  42. Why is a coaxial cable used between the quantity indicator and converter probe?
    a. To keep stray external signals from interfering with the probe signal.
  43. What effect would a stuck open filler check valve have on the LOX system?
    a. Liquid oxygen would flow out of the combination fill, buildup, and vent valve when the servicing hose is connected.
  44. A new converter has been installed and filled with liquid oxygen. Four hours later frost remains on the converter. What does this condition indicate?
    a. The vacuum has been lost and the converter isn’t serviceable.
  45. The liquid oxygen system continues to vent after disconnecting the servicing hose. Why?
    a. Check the combination buildup and vent valve. If it froze during servicing, it may still be in the VENT position.
  46. What component(s) of a liquid oxygen system would most likely be malfunctioning if gaseous oxygen is discharging from the vent port?
    a. The pressure-closing valve or the container-relief valve is defective.
  47. What are the inspection points for the mask-to-regulator hose?
    a. Inspect the hose for chaffing, collapsing, kinking, and proper length.
  48. During an inspection, the no-go part of a go-no-go gauge passes into the smaller part of the connector. What should you do?
    a. Remove and replace the connector.
  49. What safety precautions must you take when oxygen tubing is within 2 inches of electrical wiring?
    a. Cover the electrical wiring with insulation and clamp it at least one-half inch from the oxygen tubing.
  50. What are the potential discrepancies you should look for when you’re inspecting a liquid oxygen converter?
    a. Inspect for security of mounting, damage to converter, and loss of vacuum.
  51. What’s the minimum allowable distance between clamps on straight runs of oxygen tubing?
    a. A minimum of every 15 inches.
  52. What’s the ideal clearance between oxygen components and oil, fuel, and hydraulic components?
    a. 6 inches.
  53. How should anti-seize tape be applied to a fitting?
    a. Apply tape to the pipe-thread end by wrapping with the threads starting with the first thread. Use one wrap with a slight overlap on the end.
  54. How are oxygen fittings prevented from turning as the B-nuts are loosened or tightened?
    a. By holding the fitting with a wrench.
  55. Why should anti-seize tape never extend over the end of a fitting?
    a. The tape may enter the lines and cause the failure of some component or possibly restrict the flow of oxygen.
  56. What should be your main concern when replacing a bonding jumper?
    a. Ensure the bonding jumper is the proper length and is properly installed for a low-resistance connection.
  57. Give three reasons for purging a gaseous oxygen system.
    a. (1)System is depleted to zero pressure, (2)A component is replaced, (3)There’s an odor in the system.
  58. Match each component of a gaseous oxygen cart in column B to its function in column A. Items in Column B may be used only once.
    • "Column B" (A)Servicing valve, (B)Purifier cartridge, (C)Manifold control valve, (D)Low-pressure regulator, (E)Storage cylinder valves, (F)High-pressure regulator.
    • "Column A" b(1)Controls the moisture in the oxygen, e(2)Releases the oxygen from the cylinder, c(3)Releases the oxygen to the oxygen manifold, f(4)Regulates the pressure to a high-pressure system, a(5)Controls the flow of oxygen to the filler adapter, d(6)Controls the pressure to the low-pressure servicing hose
  59. Why should you release oxygen through the service valve before you connect it to the aircraft?
    a. To expel any foreign matter that may be in the hose.
  60. Why is it necessary to purge a LOX system?
    a. If a liquid oxygen system has been opened or is completely empty, it should be purged because moisture may have entered the system.
  61. What is the procedure for purging a converter assembly?
    a. After the converter assembly has been drained, connect a hot-gas purge kit and send heated oxygen through the assembly and out the vent. Then, turn off the heat and cool the unit by cold purging. Disconnect the purge kit and service immediately with liquid oxygen.
  62. How is an aircraft LOX system hot-purged?
    a. Connect a hot-purge kit to the filler valve. If it has a handle, place the buildup and vent valve in the BUILDUP position. Turn on the regulators and allow the heated oxygen to come out of the mask hose. After a specified time, turn the
  63. Why is it important to record the ambient temperature when leak testing a gaseous oxygen system?
    a. The ambient temperature can affect the pressure within the gaseous oxygen cylinders. This could give a false indication of excessive leakage.
  64. You insert a check valve leak tester into a filler valve and wipe a film of soap solution over the open end of the tester. Very quickly (before 10 seconds have elapsed) the soap bubbles out and is punctured. What does this indicate?
    a. One or more of the oxygen system check valves is leaking excessively.
  65. While using an ultrasonic leak detector, the leak cannot be detected because of surrounding background noises. What important step has been omitted?
    a. The ultrasonic leak detector meter was not zeroed to eliminate the surrounding noises.
  66. As you pass an ultrasonic leak detector probe over a line, it picks up a noise. The noise fades away as you move the probe down the line. What action should you take?
    a. Move the probe back toward the noise point. Where the noise is loudest is the point of the leak.
  67. What is the purpose of the oxygen regulator field tester?
    a. To perform an operational check of an oxygen regulator.
  68. You place the oxygen regulator supply toggle to the ON position and place the diluter toggle to the 100 percent position and breathe through an oxygen mask. For what indication are you looking?
    a. Watching for the flow indicator to appear in the regulator window.
  69. What type of insulation is used in the annular space of the TMU–27/M servicing unit?
    a. Layers of aluminized polyester film insulation.
  70. Why are thin stainless steel supports used between the inner and outer tanks?
    a. Stainless steel is stronger than most materials and the supports are thin to help prevent heat transfer by conduction.
  71. What malfunction would you suspect if the rupture disc on the outer tank blows out?
    a. There’s a leak from the inner tank to the annular space.
  72. Match each component of a liquid oxygen storage and transfer cart in column B with its function in column A. Items in column B may be used only once.
    • "Column B" (A)Pressure-buildup valve, (B)Fill-drain valve, (C)Vent line shutoff valve, (D)Relief valve, (E)Inner shell safety burst disc.
    • "Column A" c(1)When closed, allows pressure to build up in the inner tank, a(2)When open, allows the flow of liquid oxygen into a coil for vaporization, e(3)When system pressures exceed preset values, relieves excessive pressure, d(4)Normal safety protection for the tank and the transfer hose, b(5)Used to transfer liquid oxygen.
  73. Why is the quality of LOX very important?
    a. If it’s contaminated, it will affect the flight crew, as well as cause malfunction of system components.
  74. What is a possible solution to restricted liquid flow from a cryotainer?
    a. Remove, clean, and reinstall the dirty filter or replace the filter if it is still clogged.
  75. How do you repair a liquid oxygen cart with a frozen float?
    a. Purge the inner tank of all moisture.
  76. How are leaks on the control valve repaired?
    a. Tighten the packing nut. If that doesn’t stop the leak, replace the packing rings.
  77. What will cause frost on a line downstream from a closed oxygen control valve? What repair is required?
    a. A leaking control valve will cause frost. You must replace the Teflon seal in the valve or replace the valve assembly.
  78. Which technical manuals should be referenced when cleaning oxygen components?
    a. Specific technical manual, 15X-1-1.
  79. What may occur if liquid oxygen comes in contact with hydrocarbons?
    a. Spontaneous combustion.
  80. What precautions should you take to make sure internal oxygen components are not handled with your fingers?
    a. Wear disposable surgical gloves.
  81. Why should you never use shop compressed air to clean or dry oxygen components?
    a. Shop compressed air may contain hydrocarbons.
  82. What six things must be considered before you clean oxygen components?
    a. Cleaning facility, selecting a suitable cleaning agent, selecting the proper cleaning method, cleanliness inspection, cleaning agent removal and drying, packaging.
  83. What are the two methods of draining the storage and transfer tank?
    a. By using gravity or pressure.
  84. How are dirt and moisture removed from the purging air?
    a. By a cleanable metallic 40-micron filter in the purge unit.
  85. What are the power requirements for the GSU–62/M air-purging unit?
    a. Either 220 or 440 volt AC, 3 phase, 60 cycle.
  86. How can you reverse the direction of rotation of the GSU–62/M air-purging unit blower?
    a. With the phase reversal switch.
  87. What component prevents the heater on the GSU–62/M air-purging unit from overheating? At what temperature does the component shut down the unit?
    a. The overheat thermostat; 400°F.
  88. When is a cryotainer considered purged?
    a. When the air temperature at the fill-drain line outlet reaches 220°F for 1 hour.
  89. Explain the mechanical operation of a rotary vacuum pump.
    a. The drive shaft turns the rotor hub which causes the rotor blades to sweep the cylinder walls. This draws air in through the inlet; then, the blades push the air out of the discharge port.
  90. What steps must be taken to prevent oil from being drawn into the annular space when the vacuum pump is shutdown?
    a. Before you stop the pump, unlock the knob and push the seal-off plug back into the vacuum port.
  91. What are the advantages of heating the cryotainer inner tank before evacuating the annular space?
    a. The contaminants are vaporized so they can be easily removed by the vacuum pump; heating generates the “getter” material; and the vacuum attained will improve when the tank cools down.
  92. What action should you take if an air purging unit isn’t available and a cryotainer needs to be evacuated?
    a. Pressurize the inner tank with dry nitrogen or dry oil-free air to prevent air circulating. This will prevent moisture from forming in the inner tank.
  93. What effect would a partially plugged service line filter have on the operation of the cryotainer?
    a. The rate of servicing oxygen from the cryotainer would be slow.
  94. Name three malfunctions that would cause excessive venting of a cryotainer.
    a. (1)Loss of vacuum in the annular space, (2)Internal leaking through the buildup valve, (3)Improper setting of the adjustable relief valve.
  95. What is the minimum safe distance from a Libby unit when servicing or maintenance is being performed on the unit?
    a. 50 feet.
  96. Why must you use the Libby unit in a well-ventilated area?
    a. Because nitrogen displaces oxygen.
  97. How does the Libby unit pump operate?
    a. With low pressure gaseous nitrogen supplied by HX1.
  98. At what pressure will the high pressure relief valve (RV5) vent pressure from the high pressure side of the Libby unit?
    a. Excess of 4200 psig.
  99. What is the servicing pressure from the high pressure side of the Libby unit?
    a. 350-3600 psig.
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2A656 VOL 5 Q&A
2A656 VOL 5 Q&A
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