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Avionics > CABIN ATMOSPHERE CONTROL SYSTEM > Flashcards

CABIN ATMOSPHERE CONTROL SYSTEM 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 air pressure increases?

A

either a combustion air relief valve or a differential pressure regulator

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7
Q

The cabin pressure of an aircraft in flight is maintained at the selected altitude by

A

controlling the rate at which air leaves 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

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

A

continuous flow

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20
Q

The altitude controller maintains cabin altitude by modulation of the

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

ram air cycle cooling unit

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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

The main cause of contamination in gaseous oxygen systems is

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

condenser

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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

supplemental 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 is too great, the control should be adjusted to cause the

A

outflow valve to close faster

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 connection 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

When checking a freon system, a steady stream of bubbles in the sight gauge indicates the charge is

A

low

47
Q

An aircraft pressurization cycle is normally considered to be

A

one complete series of events or operations that recur regularly

48
Q

Which best describes cabin differential pressure?

A

difference between the ambient and internal air pressure

49
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

50
Q

The cabin pressurization modes of operation are

A

differential, unpressurized and isobaric

51
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

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-dyer

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 subcooler in a vapor-cycle cooling system is to

A

cool the Freon to prevent premature vaporization

64
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

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 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

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

A

when the user breathes

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 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 be identified by their

A

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

75
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

76
Q

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

A

pressure relief valves

77
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

78
Q

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

A

only no. 1 is true

79
Q

Oxygen systems in unpressurized aircraft are generally of the

A

continuous flow and pressure demand types

80
Q

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

A

regulate airflow in relation to oxygen flow when operating in emergency or diluter demean position

81
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

82
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

83
Q

A contaminated oxygen system is normally purged with

A

oxygen

84
Q

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

A

read the pressure gauge mounted on the cylinder

85
Q

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

A

Teflon tape

86
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

87
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 times that of compressed oxygen.
3. The system generators are inert below 400°F even under severe impact.
4. A distribution and regulating system similar to gaseous oxygen systems.

A

2, 3

Avionics (9 decks)

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