Environmental systems

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Environmental systems
2011-10-12 05:01:23
environmental systems pressurization aircraft AME airframe

environmental systems pressurization aircraft AME airframe
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  1. What percentage of air is oxygen?
  2. As air temperature increases , density...?
  3. What condition does the human body encounter when it becomes deprived of required oxygen?
  4. Result of incomplete burning of fuels ?colorless odorless and tasteless
    Carbon Monoxide
  5. What are the 4 types of oxygen supplementation?
    • Compressed gas
    • Liquid oxygen
    • Solid state
    • Mechanically separated
  6. Compressed O2 is stored in what color cylinders?
  7. Typical compressed O2 bottles are pressured to what PSI?
    1800 - 2400 psi
  8. What is one advantage and one disadvantage of compressed gas O2
    • adv: ease of handling
    • dis: Weight
  9. What is the #1 benefit on liquid oxygen?
    Economical in space and weight
  10. One disadvantage of O2 generators?
    • Single use
    • gets very hot when in use
  11. what are 3 types of O2 storage bottles?
    • Steel
    • aluminum
    • composite
  12. O2 cylenders must be tested at what pressure?
    5/3 of their working pressure
  13. composite bottles must be tested every... years?
  14. steel bottles must be teseted every .... years?
  15. Cylenders must be taken out of use after how many year2?
    24 years
  16. What is critical about checking on exuast shroud type heaters ?
    leak checking around welded studs , carbon monoxide poisoning
  17. What are the welded studs for on exuast shroud type heaters?
    Increase surface area for more effective heating
  18. When are electric resistance type heaters primarily used?
    supplemental heat, usually on the ground
  19. What is installed on electric resistance type heaters?
    safety switch to turn them off in case of fan failure
  20. What heating is primarily used for large transport catagory aircraft?
    Bleed air
  21. Medium twin engine aircraft are usually heated with what king of heat?
    Combustion type heaters (Janitrol)
  22. On a Combustion heater , what 3 switches control the fuel soleniod?
    • Limit
    • overheat
    • pressure switchs
  23. What does the duct limit switch do on a combustion heater?
    shuts off fuel when there is not enough airflow to remove heat from the duct
  24. What does the overheat switch do on a combustion type heater?
    Set higher than duct limit switch but below fire temp, closes fuel , combustion air and ignition
  25. The refrigerant used in most vapor cycle aircraft cooling systems?
    R12 , freon 12
  26. In a vapor cycle cooling system , where is the heat removed from the air?
    The evaporator
  27. Vapor cycle cooling system, as the refrigerant changes state , what happens to the temperature?
    temperature of the coolant remains the same
  28. What happens to water that enters the system while servicing ?(vapor cycle a/c)
    desicant in the receiver/dryer catches it
  29. what is the boiling point on freon 12?
    21.6 f
  30. where can you find the correct lubricant for the A/c pump?
    maintenance manual
  31. On a belt driven freon compressor , how is the component cycled on and off?
    magnetic clutch
  32. what component controls the amount of coolant that is sprayed into the evaporator? vapor cycle a/c
    thermal expansion valve
  33. what is the purpose of the thermal expansion valve? vapor cycle a/c
    to meter the correct amount of coolant into the evaporator
  34. What 2 components in a vapor cycle a/c system seperate the high and low sides?
    • thermal expansion valve
    • compressor
  35. what is the pressure indicator travel for the low side gauge? vapor cycle a/c
    -60 psi to 60 psi
  36. how do you check a vapor cycle a/c system for leaks?
    • soapy water
    • electronic sniffer
  37. how are the hoses for the vapor cycle a/c manifold easily identified?
    • by color
    • red=hi
    • blue=low
    • yellow=center
  38. how is refrigerant measured?
    by weight
  39. why must a vapor cycle a/c system be evacuated before refilling?
    to remove any water vapor in the air that may lead to icing in the a/c system
  40. how is full refrigerant seen in an a/c system ?
    no more bubbles in the sight glass
  41. why is it critical to aviod getting liqiud refigerant in the low side while filling?
    it will enter the compressor pump and hydraulicly lock it .. causing major damage
  42. what must be done before checking compressor oil level in the a/c vapor system?
    run a/c for 15 minutes
  43. what is latent heat?
    the state changes but temp stays constant
  44. what is superheat?
    temperature created by a gas above its boiling pointof the base liquid
  45. what is the purpose of the landing gear switch in the janitrol heater circuit?
    to turn on the fans to supply air on the ground, because they cannot rely on ram air anymore
  46. what TC document requires us to check muff heaters for leaks regularly?
  47. what is the purpose of a "pack" valve on a turbine ACM cooling system?
    to take or shut bleed air from the engines
  48. where is most of the heat energy removed from the ACM system?
    the expansion turbine in ACM
  49. Why is there a water seperator on an ACM?
    prevent icing in system
  50. what is the purpose of the temp control valve that bypasses the air around compressor and turbine of ACM?
    controls cabin temperature
  51. How do you do a pressure decay test on acombustion heater liner?
    plug it off, pressure to 6 psi, wait 45 seconds and check for 1 psi remaining
  52. why is an ACM often called a pack?
    Boeing calls it "Pnuematic Air Conditioning Kit"
  53. what are the 2 air pressures in combustion heater?
    • ventilation air and combustion air
    • ventilation must always be higher to prevent CO poisoning
  54. How often do you do a pressure decay test on a janitrol?
    500 hours or seasonally
  55. PACK fans are driven 4 ways?
    • Mechanicly linked
    • hydraulicly
    • electricly
    • bleed air driven