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Airframe > Cabin Atmosphere Control Systems > Flashcards

Cabin Atmosphere Control Systems Flashcards

1
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.

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2
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.

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3
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.

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4
Q

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

A

Oil seepage

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5
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 temperature is too low?

A

Compressor

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6
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.

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7
Q

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

A

High pressure liquid.

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8
Q

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

A

Pressure relief valves

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9
Q

What is ventilating air used for on a combustion heater?

A

Carries heat to the places where needed.

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10
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.

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11
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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12
Q

Which selection 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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13
Q

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

A

Calibrated orifice

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14
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.

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15
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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16
Q

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

A

Chemical oxygen generator systmes.

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17
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.

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18
Q

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

A

Ambient air

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19
Q

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

A

The system is under charged.

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20
Q

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

A

Pressure reducer valve

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21
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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22
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

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23
Q

What type of oxygen system uses the rebreather bag-type mask?

A

Continuous flow.

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24
Q

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

A

Regulate airflow in relation to cabin altitude when in driver demand position.

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25
Q

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

A

Moisture

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26
Q

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

A

Moisture to collect in the bottle.

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27
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.

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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 in the engine exhaust as a heat source?

A

Supplement physical inspections with periodic operational carbon monoxide detection tests.

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29
Q

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

A

Expansion turbine

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30
Q

On 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.

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31
Q

A contaminated oxygen system is normally purged with

A

Oxygen

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32
Q

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

A

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

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33
Q

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

A

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

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34
Q

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

A

Special high grade refrigeration oil.

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35
Q

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

1) An adjustable oxygen release rate.
2) A volume storage capacity about three ties that of compressed oxygen.
3) The system generators are inert below 400 degrees F even under sever impact.
4) A distribution and regulating system similar to gaseous oxygen systems.

A

2&3

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36
Q

The basic-air cycle cooling system consists of

A

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

37
Q

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

A

Delivery air duct check valve.

38
Q

1) A small amount of water in a vapor-cycle cooling system can freeze in the receiver-dryer and stop the entire system operation.
2)Water in a vapor-cycle cooling system will react with refrigerant to form hydrochloric acid which is highly corrosive to the metal in the system.
Regarding the above statements,

A

Only no.2 is true

39
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.

40
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

Condenser

41
Q

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

A

Teflon tape

42
Q

The primary function of the cabin pressurization system airflow valve is to

A

Maintain the desired cabin pressure

43
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

44
Q

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

A

All positive pressure from the cabin.

45
Q

The cabin pressure control setting has a direct influence upon the

A

Outflow valve opening

46
Q

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

A

Bleed air

47
Q

An aircraft pressurization cycle is normally considered to be

A

One complete series of events or operations that recur regularly

48
Q

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

A

Every 5 years

49
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

50
Q

The cabin pressurization modes of operation are

A

differential, unpressurized, and isobaric.

51
Q

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

A

Low pressure vapor

52
Q

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

A

Main landing gear operated switch.

53
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.

54
Q

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

A

Outflow valve

55
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

56
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.

57
Q

The purpose of pressurizing aircraft cabins is to
1) Create the proper environment for prevention of hypoxia.
2) Permit operation at high altitudes.
Regarding the above statements,

A

Both no.1 and no.2 are true

58
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.

59
Q

The air-cycle cooling system produces cold air by

A

Extracting heat energy across an expansion turbine.

60
Q

Oxygen systems in unpressurized aircraft are generally of the

A

Continuous-flow and pressure-demand types.

61
Q

In the diluter demand oxygen regulator, when does the demand valve operate?

A

When the user breathes.

62
Q

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

A

Negative pressure relief valve.

63
Q

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

A

Evaporator coils

64
Q

1) Oxygen used in aircraft systems is at least 99.5% and is practically water free.
2) Oxygen used in aircraft systems is at least 99.5% and is hospital quality.
Regarding the above statements,

A

only no.1 is true

65
Q

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

A

Air cycle air conditioning

66
Q

A pressurization controller uses

A

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

67
Q

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

A

Read the pressure gauge mounted on the cylinder.

68
Q

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

A

Transfer heat from the freon gas to ambient air.

69
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.

70
Q

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

A

Outflow valve to close faster

71
Q

Which best describes cabin differential pressure?

A

Difference between the ambient and internal air pressure.

72
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.

73
Q

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

A

Pressure test with water.

74
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.

75
Q

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

A

High-pressure vapor

76
Q

1) Usually bleed air from a gas-turbine engine compressor can be safely used for cabin pressurization.
2) Independent cabin condition air machines (air cycle machine) can be powered by bleed air from an aircraft turbine engine compressor.
Regarding the above statements,

A

Both no.1 and no.2 are true.

77
Q

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

A

Low-pressure liquid

78
Q

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

A

Receiver-dryer

79
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 F; 6 hours later the temperature was 51 degrees F. (A 5 PSI change is the maximum allowable in a 6-hour period.) What pressure gauge readings would be acceptable to remain within the allowable limits?

A

445 to 450 PSI

80
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.

81
Q

The purpose of a subcooler in a vapor-cycle cooling system is to

A

Cool the freon to prevent premature vaporization.

82
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.

83
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.

84
Q

When refrigerant-12 is passed over an open flame, it

A

Changes to phosgene gas

85
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.

86
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

87
Q

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

A

Green color and words ‘Aviators Breathing Oxygen’ stenciled in 1-inch white letters.

88
Q

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

A

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

89
Q

What controls the operation of the cabin pressure regulator?

A

Cabin altitude

Airframe (17 decks)

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