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Airframe Writtens > Cabin Atmosphere Control Systems > Flashcards

Cabin Atmosphere Control Systems Flashcards

1
Q

Which section of a turbine engine provides high pressure bleed air to an air cycle machine for pressurization and air conditioning?

A

Low or high pressure compressor.

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2
Q

At which component in an air-cycle cooling system does air undergo a pressure and temperature drop?

A

Expansion turbine.

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3
Q

In a freon vapor-cycle cooling system, where is cooling air obtained for the condenser?

A

Ambient air.

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4
Q

What is ventilating air used for on a combustion heater?

A

Carries heat to the places where needed.

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5
Q

Turbine engine air used for air conditioning and pressurization is generally called…

A

bleed air.

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6
Q

In the combustion heater, combustion air system, what prevents too much air from entering the heaters as pressure increase?

A

Either a combustion air relief valve or a differential pressure regulator.

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7
Q

How is the cabin pressure of an aircraft maintained in flight?

A

By controlling the rate of the air flowing out of the cabin.

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8
Q

What controls the operation of the cabin pressure regulator?

A

Cabin altitude.

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9
Q

The basic air-cycle cooling system consists of…

A

a source of compressed air, heat exchangers, and a turbine.

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10
Q

The purpose of the dump valve in a pressurized aircraft is to relieve…

A

all positive pressure from the cabin.

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11
Q

What component might possibly be damaged if liquid refrigerant is introduced into the low side of a vapor-cycle cooling system when the pressure is too high or the outside air temperature is too low?

A

Compressor.

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12
Q

How can it be determined that a vapor-cycle cooling system is charged with the proper amount of freon?

A

Air bubbles in the sight glass disappear.

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13
Q

When charging a vapor-cycle cooling system after evacuation, the low-pressure gauge fails to come out of a vacuum. What is indicated?

A

Blockage in the system.

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14
Q

What component in a vapor-cycle cooling system would most likely be at fault if a system would not take a freon charge?

A

Expansion valve.

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15
Q

Frost or ice buildup on a vapor-cycle cooling system evaporator would most likely be caused by…

A

inadequate airflow through the evaporator.

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16
Q

What test is used to determine the serviceability of an oxygen cylinder?

A

Pressure test with water.

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17
Q

How often should standard weight high-pressure oxygen cylinders be hydrostatically tested?

A

Every 5 years.

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18
Q

To be eligible for recharging, a DOT 3HT oxygen cylinder must have been hydrostatically tested every three years and be retired from service after…

A

24 years or 4,380 filling cycles.

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19
Q

Which oxygen system employs a regulator that operates only when the user inhales?

A

Demand-flow system.

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20
Q

The component that determines the pressure level in the cabin is the cabin air pressure…

A

outflow valve.

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21
Q

Hot compressor bleed air operates the conditioned air system on some turbine aircraft, cold air supplied by the…

A

air cycle air conditioning.

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22
Q

For use in pressurized aircraft, which is generally the least complicated and requires the least maintenance?

A

Chemical oxygen generator systems.

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23
Q

What is the main cause of contamination in a gaseous oxygen system?

A

Moisture.

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24
Q

Where does the last stage of cooling in an air-cycle air conditioning system occur?

A

Expansion turbine.

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25
Q

The point at which freon flowing through a vapor-cycle cooling system gives up heat and changes from a gas to a liquid is the…

A

condensor.

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26
Q

The point at which freon flowing through a vapor-cycle cooling system absorbs heat and changes from a liquid to a gas is the…

A

evaporator.

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27
Q

How is the cabin pressure of a pressurized aircraft usually controlled?

A

By an automatic outflow valve that dumps all the pressure in excess of the amount for which it is set.

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28
Q

Which is considered a good practice concerning the inspection of heating and exhaust systems of aircraft utilizing a jacket around the engine exhaust as a heat source?

A

Supplement physical inspections with periodic operational carbon monoxide detection tests.

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29
Q

On some cabin pressurization systems, pressurization on the ground is restricted by the…

A

main landing gear operated switch.

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30
Q

The cabin pressure control setting has a direct influence upon the…

A

outflow valve opening.

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31
Q

The function of the evaporator in a freon cooling system is to…

A

lower the temperature of the cabin air.

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32
Q

What is the purpose of a mixing valve in a compressor bleed air air-conditioning system?

A

Control the supply of hot, cool, and cold air.

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33
Q

What component of a pressurization system prevents the cabin altitude from becoming higher than airplane altitude?

A

Negative pressure relief valve.

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34
Q

If the liquid level gauge in a vapor-cycle cooling system indicates a low freon charge, the system should…

A

be operated for a period of time to reach a stable condition and then the freon level rechecked.

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35
Q

If the cabin rate of climb too great, the control should be adjusted to cause the…

A

outflow valve to close faster.

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36
Q

The position of the thermostatic expansion valve in a vapor-cycle cooling system is determined by temperature and pressure of the…

A

freon in the outlet of the evaporator.

37
Q

The function of the condenser in a freon cooling system is to…

A

transfer heat from the freon gas to ambient air.

38
Q

The function of an expansion valve in a freon cooling system is to act as a metering device and to…

A

reduce the pressure of the liquid freon.

39
Q

Which prevents a sudden loss of pressurization in the event that there is a loss of the pressurization source?

A

Delivery air duct check valve.

40
Q

When servicing an air conditioning system that has lost all of its freon, it is necessary to…

A

check oil and add as necessary, evacuate the system, and add freon.

41
Q

The primary function of the cabin pressurization system outflow valve is to…

A

maintain the desired cabin pressure.

42
Q

One purpose of a jet pump in a pressurization and air conditioning system is to…

A

provide for augmentation of airflow in some areas of the aircraft.

43
Q

After cleaning or replacing the filtering element in a combustion heater fuel system, the system should be pressurized and…

A

all connections checked for leaks.

44
Q

The operation of an aircraft combustion heater is usually controlled by a thermostat circuit which…

A

alternately turns the fuel on and off, a process known as cycling.

45
Q

The air-cycle cooling system produces cold air by…

A

extracting heat energy across an expansion turbine.

46
Q

(Refer to Figure 13.) Determine what unit is located immediately downstream of the expansion valve in a freon refrigeration system.

A

Evaporator coils.

47
Q

What does a steady stream of bubbles indicate when servicing a vapor cycle air conditioning system?

A

The system is under charged.

48
Q

An aircraft pressurization cycle is normally considered to be…

A

one complete series of events or operations that recur regularly.

49
Q

Which best describes cabin differential pressure?

A

Difference between the ambient and internal air pressure.

50
Q

Composite oxygen bottles that conform to DOT-E-8162 have a service life of…

A

15 years or 10,000 filling cycles whichever occurs first.

51
Q

The cabin pressurization modes of operation are…

A

differential, unpressurized, and isobaric.

52
Q

A pressurization controller uses…

A

barometric pressure, cabin altitude, and cabin rate of change.

53
Q

What unit in a vapor-cycle cooling system serves as a reservoir for the refrigerant?

A

Receiver-dryer.

54
Q

What is the condition of the refrigerant as it enters the condenser of a vapor-cycle cooling system?

A

High-pressure vapor.

55
Q

What is the condition of the refrigerant as it enters the evaporator of a vapor-cycle cooling system?

A

Low-pressure liquid.

56
Q

The evacuation of a vapor-cycle cooling system removes any water that may be present by…

A

lowering the boiling point of the water and drawing out the vapor.

57
Q

What is the condition of the refrigerant as it leaves the evaporator of a vapor-cycle cooling system?

A

Low-pressure vapor.

58
Q

What is the condition of the refrigerant as it leaves the condenser of a vapor-cycle cooling system?

A

High-pressure liquid.

59
Q

In what position should the bottle be placed when adding liquid freon to a vapor-cycle cooling system?

A

Vertical with the outlet at the bottom.

60
Q

When purging a freon air conditioning system, it is important to release the charge at a slow rate. What is the reason for the slow-rate discharge?

A

Prevent excessive loss of refrigerant oil.

61
Q

When a vapor-cycle cooling system is not in operation, what is an indication that the system is leaking freon?

A

Oil seepage.

62
Q

In an operating vapor-cycle cooling system, if the two lines connected to the expansion valve are essentially the same temperature, what does this indicate?

A

The expansion valve is not metering freon properly.

63
Q

The purpose of a sub cooler in a vapor-cycle cooling system is to…

A

cool the freon to prevent premature vaporization.

64
Q

A small amount of water in a vapor cycle cooling system can freeze…

A

in the expansion valve and stop the entire system operation.

65
Q

When Refrigerant-12 is passed over an open flame, it…

A

changes to phosgene gas.

66
Q

What type of oil is suitable for use in a vapor-cycle cooling system?

A

Special high grade refrigeration oil.

67
Q

When an aircraft’s oxygen system has developed a leak, the lines and fittings should be…

A

bubble tested with a special soap solution manufactured specifically for this purpose.

68
Q

If oxygen bottle pressure is allowed to drop below a specified minimum, it may cause…

A

moisture to collect in the bottle.

69
Q

What controls the amount of oxygen delivered to a mask in a continuous-flow oxygen system?

A

Calibrated orifice.

70
Q

When does the diluter-demand regulator operate?

A

When the user inhales.

71
Q

The primary difference between aviation breathing oxygen and other types of commercially available compressed oxygen is that…

A

aviation breathing oxygen has had all the water vapor removed.

72
Q

What is used in some oxygen systems to change high cylinder pressure to low system pressure?

A

Pressure reducer valve.

73
Q

In a high-pressure oxygen system, if the pressure reducer fails, what prevents high-pressure oxygen from entering the system downstream?

A

Pressure relief valve.

74
Q

High-pressure cylinders containing oxygen for aviation use can identified by their…

A

green color and the words AVIATOR’S BREATHING OXYGEN stenciled in 1-inch white letters.

75
Q

(Refer to Figure 14.) One hour after an oxygen system was charged for a leakage check, the oxygen pressure gauge read 460 psi at 63 Degrees Fahrenheit; 6 hours later the temperature was 51 Degrees Fahrenheit. (A 5 psi change is the maximum allowable in a 6-hour period.) What pressure gauge reading would be acceptable to remain within the allowable limits?

A

445-450 psi.

76
Q

An aircraft oxygen bottle may be considered airworthy if it has been hydrostatically tested and identified…

A

with the test date, DOT number, and serial number stamped on the cylinder near the neck.

77
Q

In a gaseous oxygen system, which of the following are vented to blow out plugs in the fuselage skin?

A

Pressure relief valves.

78
Q

What is the purpose of pressurizing the aircraft cabin?

A

To make human flight possible in the hostile environment of the upper atmosphere.

79
Q

Oxygen used in aircraft systems…

A

is at least 99.5% pure and is practically water free.

80
Q

Oxygen systems in unpressurized aircraft are generally of the…

A

continuous-flow and pressure-demand types.

81
Q

The purpose of the airflow metering aneroid assembly found in oxygen diluter demand regulators is to…

A

regulate airflow in relation to cabin altitude when in diluter demand position.

82
Q

If a high-pressure oxygen cylinder is to be installed in an airplane, it must meet the specifications of the…

A

Department of Transportation.

83
Q

Before a high-pressure oxygen cylinder is serviced, it must be the correct type and have been…

A

hydrostatically tested within the proper time interval.

84
Q

A contaminated oxygen system is normally purged with…

A

oxygen.

85
Q

How should you determine the amount of oxygen in a portable, high-pressure cylinder?

A

Read the pressure gauge mounted on the cylinder.

86
Q

What may be used as a lubricant on oxygen system tapered pipe thread connections?

A

Teflon tape.

87
Q

On a transport category aircraft what might be an indication of an over pressure event of the aircraft oxygen system?

A

The green thermal expansion disk missing.

88
Q

Which of the following are characteristics a chemical or solid-state oxygen system?

A

A volume storage capacity about three times that of compressed oxygen and system generators that are inert below 400 Degrees Fahrenheit, even under severe impact.

Airframe Writtens (34 decks)

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