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M11 > 11.4 air con/cabin pressure > Flashcards

11.4 air con/cabin pressure Flashcards

1
Q

where is an aircrafts pressurised air received from

A

engines, APU, Ground source

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2
Q

what happens to temperature as pressure increases

A

temperature increase

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3
Q

what stage in the engine is the compressed air taken from

A

compressor

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4
Q

when is low pressure air used

A

take off, climb, cruise

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5
Q

when is high pressure air used

A

low engine RPM

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6
Q

how many bleed ports will be open at a time

A

1

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7
Q

what is air pressure controlled by

A

pressure regulating valve or bleed air valve

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8
Q

if we use bleed air from the compressor what it there a reduction in

A

engine performance

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9
Q

what is used for cabin pressure to prevent usage of the engines air

A

independent cabin compressor

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10
Q

cabin compressors are divided into what 3 groups

A

positive displacement compressor, centrifugal compressor, turbo compressor

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11
Q

what does CAC stand for

A

cabin air compressor

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12
Q

to meet high demands for ground power when the engines arent running what is used

A

APU

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13
Q

what type of engine is a typical APU

A

small turbine engine

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14
Q

if an APU is used in flight what the bleed extraction limited to (height)

A

22,000ft

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15
Q

what is the ACP

A

air conditioning pack

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16
Q

if an aircraft doesnt have any engine on or APU running whats used for the air supply

A

pneumatic ground cart

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17
Q

what does ACS stand for

A

air conditioning system

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18
Q

whats the approximate cruising temp

A

-40 degrees celcius

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19
Q

whats the function of the air conditioning system

A

maintain comfortable air temperature in the aircraft

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20
Q

what range of temps can most ACS produice

A

21-27 degrees celcius

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21
Q

what are the 2 types of ACS system used on aircraft

A

air cycle machine, vapour cycle machine

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22
Q

where are air cycle machines commonly used

A

passenger aircraft

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23
Q

where are vapour cycle machines used

A

small and medium sized aircraft

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24
Q

what are the functions of the ACS

A

ventilation, heated air, cooled air, cabin pressure, equipment cooling

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25
Q

whats the size of the hose off the pneumatic cart

A

4 inch diameter

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26
Q

where does the air cycle conditioner get its air from

A

engine bleed air or APU

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27
Q

where is the air cycle conditioner usually located

A

lower fuselage or tail section

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28
Q

at extreme altitudes the bleed air is extremely hot, what does it use to cool the air

A

air cooling system

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29
Q

air arriving from the bleed air system and entering the heat exchange has an average psi of what and what temperature

A

30 to 40 psi, 150 degrees celcius

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30
Q

what does bleed air temp reduce to after passing the heat exchanger

A

100 degrees celcius

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31
Q

what temp is the bleed air after entering the compressor

A

30 to 40 degrees celcius

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32
Q

what temp is the bleed air after going through the secondary heat exchanger

A

60 - 70 degrees celcius

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33
Q

what does the pack or flow control valve do

A

regulates bleed air from the pneumatic manifold into the air cycle machine

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34
Q

how are pack flow and control valved controlled and operated

A

controlled electrically, operated pneumatically

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35
Q

what type of valve is the pack valve

A

venturi type butterfly valve

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36
Q

what is the main function of the pack valve

A

control the airflow into the cabin

37
Q

at 8000 ft what is the mass air flow into the cabin

A

0.86 kg/s

38
Q

on the ground what is the mass air flow into the cabin

A

1.1 kg/s

39
Q

how are air conditioning systems able to save energy

A

adjusting their air output to number of passengers

40
Q

what is the ACM

A

air cycle machine

41
Q

what are the 2 types of ACMs used

A

oil lubricataed, air lubricated

42
Q

what are the 2 functions of the condenser/reheater

A

cool air in AC pack, heat air in AC pack

43
Q

whats the use of trim air valves

A

accurate temp controlled air

44
Q

where is the RAM air door located

A

underside of aircraft

45
Q

what are the 5 components of a vapour cycle machine

A

refrigerant, compressor, condenser, expansion valve, evaporator

46
Q

what is the refrigeration process in order

A

compression, condensation, receiver dryer, expansion, evaporation, repeat

47
Q

where is the receiver dryer located in a vapour cycle system

A

downstream of the condenser and upstream of the expansion valve

48
Q

what are the majority of evaporators constructed from

A

copper or aluminium tubing

49
Q

what is conditioned air distributed through

A

ducts

50
Q

on modern turbine powered aircraft what is conditioned air also used for

A

cabin pressurisation

51
Q

during long distance flights what is likely to happen to the air

A

becomes very dry after being repeatedly recycled

52
Q

what do humidifiers do for the passengers

A

hydration, better taste, sleep quality, reducing jet lag

53
Q

what percentage of the cabin air is normally filtered and recirculated

A

50%

54
Q

whats the use of the cabin outflow valve

A

controls cabin pressure by controlling the release of air

55
Q

what are the 2 safety valves

A

positive, negative

56
Q

what is the use of the positive safety valve

A

relives positive cabin pressure when maximal is exceeded

57
Q

when will the positive safety valve open (psi)

A

maximum between 8-10 psi

58
Q

what do negative relief valves do

A

prevents excessive negative differential

59
Q

what way do positive relief valves open

A

outward

60
Q

what way do negative relief vales open

A

inward

61
Q

simply describe negative/positive relief valves

A

negative - under pressure so puts more air in
positive - over pressure so reliefs

62
Q

at what psi will negative relief valves open

A

0.5-1 psi

63
Q

what valves are used to quickly dump air and air pressure from the cabin

A

dump valves

64
Q

name the 3 pressurisation gauges/indicators

A

cabin altimeter, cabin rate of climb, cabin differential pressure

65
Q

what are the 2 modes of pressurisation system operation

A

auto (1 and 2) and manual

66
Q

how many controllers are in use at any time in the pressurisation system

A

1

67
Q

during taxi what is the pressurisation GROUND/FLIGHT switch on

A

FLIGHT

68
Q

during take off/climb what controls the amount of cabin pressure to altitude

A

outflow valve

69
Q

in cruise does the cabin pressure change

A

no it stays constant

70
Q

what does the cabin pressure controller do

A

controls cabin air pressure

70
Q

what type of controls do modern aircraft use for cabin pressurisation control

A

pneumatic, electrical, electronic

71
Q

on modern aircraft how many cabin pressure controller are there

A

two controllers, or 1 with a redundant circuitry

72
Q

what is the ADC

A

air data computer

73
Q

what is the FMS

A

flight management system

74
Q

what is the best type of leak detector in air conditioning systems

A

electronic leak detector

75
Q

the best leak detector of a air con system could detect what leakage per year

A

1/2 ounce

76
Q

what leak detection methods other than a detector can be used

A

soapy solution, leak detection dye

77
Q

what is R12

A

non-toxic and non-flammable gas, toxic to ozone layer

78
Q

whats the main type of servicing equipment for vapour cycle air

A

manifold

79
Q

on the manifold air vapour servicing machine whats the lower pressure/high pressure gauges psi range

A

low 0 - 150 psi
high 0 - 500 psi

80
Q

what colour is the low pressure hose on the air vapour servicing manifold

A

blue

81
Q

what colour is the high pressure hose on the air vapour servicing manifold

A

yellow

82
Q

to ensure all water is removed from a vacuum pump how long is it help before use

A

15-30 mins

83
Q

what is an aircraft bleed air leak

A

uncontrolled loss of bleed air from any system

84
Q

what is a major concern with pressurisation and air con systems

A

temperature

85
Q

if overheat was to happen at what temp will an OVERHEAT warning display

A

pack overheat - 260 plus
outlet temp - 230 plus

86
Q

why is low cabin humidity good and bad

A

prevents bacteria and fungus, promotes fatigue and dehydration

87
Q

on the central warning panel what do all 4 colours mean

A

red - warning
amber - caution
green - advisory
white - advisory

88
Q
A

M11 (15 decks)

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