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M11 R > M11.4 > Flashcards

M11.4 Flashcards

1
Q

What type of gas is used in pneumatics?

A

Air

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2
Q

Other than the engines what also supplies pneumatic systems?

A

The APU

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3
Q

What are the two types of pressure that have been bled from the compressor?

A

Intermediate pressure and high pressure

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4
Q

What is used to regulate bleed air temperature from the engine?

A

A built in pre-cooler

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5
Q

How does the engine pre-cooler lower the bleed air temperature?

A

By using fan air

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6
Q

How is the amount of pressurisation calculated?

A

By using pressure differential

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7
Q

What is meant by pressure differential?

A

The difference in pressure between the aircraft air pressure and ambient air pressure

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8
Q

What is classified as high pressure differential?

A

8-10psi

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9
Q

What is classified as low differential pressure?

A

3.5-5 psi

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10
Q

What fuselage areas are not pressurised?

A
  • radome
  • landing gear bays
  • tail cone
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11
Q

What is the acceptable amount of fresh air that needs to be supplied to the cabin?

A

0.283 cubic metres per minute per person

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12
Q

What temperature range do aircraft need to be able to supply?

A

18-30 Celsius

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13
Q

What is pressurisation a compromise between?

A

Passenger comfort and structural design

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14
Q

The regulations state that what is a reasonable cabin altitude?

A

8,000 feet

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15
Q

What is the hot air from upstream of the packs know as?

A

Trim air

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16
Q

Where are the conditioning packs, valves, mixing unit located?

A

Centre wing box area

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17
Q

What are the three types of cooling devices on an aircraft?

A
  • heat exchanger
  • vapour-cycle machine
  • air-cycle machine
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18
Q

How does a heat exchanger work?

A

It allows one substance to flow through a pipe which is surrounded by another substance so they exchange heat

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19
Q

When are vapour cycle machines used?

A

When engine bleed is not available

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20
Q

How does a vapour cycle machine work?

A

It uses a cold liquid to cool something but whilst it gets hot it evaporates but then gets collected and cooled again by ambient air

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21
Q

How does an air cycle machine work?

A

It takes warm bleed air and puts it into a compressor where temperature and pressure increase. Then passes through ambient air which cools but pressure remains then it enters a turbine where pressure lowers along with temperature

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22
Q

What catalyst is used inside an ozone converter?

A

Palladium

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23
Q

What is the job of a pack valve?

A

It determines the amount of air going to the cabin

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24
Q

How do you find volumetric flow?

A

By dividing mass flow by density

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25
Q

What does the air conditioning airflow depend on?

A

The amount of passengers onboard

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26
Q

What turns everything in the air cycle machine?

A

The expanded air in the turbine?

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27
Q

If the air cycle machine has air available what s it said to be?

A

Self sustaining

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28
Q

What is the air cycle machine also known as?

A

Boot-strap air cycle machine

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29
Q

What are the two heat exchangers called?

A
  • primary heat exchange (before compressor)

- secondary / main heat exchanger (before turbine)

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30
Q

Why is a bypass valve install in the air conditioning system?

A

To allow hot air to meet the new cold air at the end

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31
Q

What happens to the turbine after using the bypass valve?

A

It slows down due to loss of pressure

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32
Q

When would the bypass valve open and close?

A

It would open when the temperature is too low and close when its too high

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33
Q

What does changing the amount of ram air flow do to the air conditioning system?

A

It alters it’s efficiency

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34
Q

What is the ram air outlet called?

A

Ram air exit R.A.E

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35
Q

What does the pack outlet temperature depend on?

A

Ram inlet, ram outlet and bypass valve

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36
Q

What type of duct is the ram air inlet?

A

NACA

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37
Q

What type of door is the ram air outlet?

A

Flap or Louvre

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38
Q

Why is a fan located in the ram air duct?

A

Because there is no ram air whilst on the ground

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39
Q

Why is water removed from the air conditioning system?

A

Because temperature can reach -50 Celsius

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40
Q

What can carry more water, hot or cold air?

A

Hot air

41
Q

What are the two places water can be separated in the cooling pack?

A

The high or low pressure loop

42
Q

Where is separated water sent in the air conditions system?

A

To the ram air to increase cooling efficiency

43
Q

How does a water separator work?

A

It spins the air to for the water o the sides

44
Q

Why is a coalescer used in the water separator?

A

To increase water droplet size

45
Q

What are used in the water extractor to spin the air and water?

A

Swirl vanes

46
Q

What is meant by dew point?

A

The point at which the dry conditioned air mixes with the warm unconditioned bypass air

47
Q

What is the average temperature of the dew point?

A

10 Celsius

48
Q

What does the pack controller assume when there is a pressure increase?

A

There is ice

49
Q

What does each air conditioning pack have?

A

It’s own pack controller and a back up controller

50
Q

In flight what must happen for maximum cooling from the air conditioning system?

A

Ram air doors open and bypass valve closed

51
Q

In flight what must happen for maximum heating from the air conditioning system?

A

Ram air doors nearly closed and bypass valve open

52
Q

During take off and landing what position is the ram air inlet?

A

Fully closed to prevent FOD

53
Q

What would happen if the air conditioning by-pass valve failed open?

A

It will start to overheat

54
Q

What will happen if the air conditioning by-pass valve fails in the closed position?

A

It will start to freeze

55
Q

After the the packs have made cold air where does it go?

A

Into mixing chamber then into the cabin

56
Q

What does the cabin mixing unit mix together?

A

New pack air and old cabin air

57
Q

What is meant by gasper system?

A

It’s when the passengers get there own air supply from the hat racks

58
Q

What is it called when the mixing unit re-uses old cabin air?

A

Recirculating system

59
Q

What is the trim air system?

A

It is a set of valves that help control individual cabin zone temperatures

60
Q

What is the computer called that controls the cabin zonal temperature?

A

Zone controller

61
Q

Why must the air going to the mixing unit be colder than the set temperature?

A

Because it will be mixed with recirculated warm air

62
Q

What do protection circuits do?

A

Prevent the system from duct overheat in the event of a component failure

63
Q

Why must there be a window or door open when starting you air conditioning system?

A

To prevent pressure build up

64
Q

What temperature does the cargo heating automatically come on at?

A

7 Celsius

65
Q

What are the two ways the cargo bays are heated?

A

Hot bleed air or electrical heaters

66
Q

What is the name of the computer that controlled the cargo temperature?

A

Zone temperature controller

67
Q

What happens if the whole cargo ventilation system fails?

A

Two blowers kick in and use cabin air

68
Q

What is the equipment cooling system separate to?

A

Air conditioning system

69
Q

What is a skin heat exchanger?

A

Warm air flows through a duct onto the cold aircraft skin to exchange temperature

70
Q

What are the two modes the equipment cooling system can be in?

A

Inboard (exhaust air stays in) or outboard (exhaust air goes out)

71
Q

What is used if the ambient air is too cold for cooling?

A

Cabin air

72
Q

Atmospheric pressure decrease with?

A

An increase in altitude

73
Q

What is atmospheric pressure measured in?

A

Hectopascals

74
Q

What is the abbreviation of differential pressure?

A

Delta p

75
Q

What is differential pressure measured in?

A

Psi

76
Q

What is 14.5 psi equal to in newtons?

A

10 newtons per cm2

77
Q

What is meant by positive rate of climb/ vertical speed?

A

The altitude climbed in the time it took

78
Q

What happens to cabin pressure during decent?

A

The pressure increases

79
Q

What is the maximum positive cabin rate?

A

500ft/min

80
Q

What is the maximum negative cabin rate?

A

300ft/min

81
Q

What must you do if cabin altitude starts to increase?

A

Reduce the amount of air that leaves the cabin

82
Q

What happens when cabin altitude increases above normal values at 10,000ft?

A

Flight crew get a warning

83
Q

What happens when cabin altitude increases above normal values at 14,000ft?

A

Oxygen masks deploy

84
Q

What happens when cabin altitude increases above normal values at 15,000ft?

A

Outflow valves close automatically

85
Q

What increase when differential pressure increases?

A

Aircraft structure stress

86
Q

What is in place to reduce the risk of structural damage due to pressure?

A

Positive pressure relief valves

87
Q

What psi do the positive pressure relief valves open?

A

8.5 psi

88
Q

Why is having a negative differential pressure bad?

A

Because the pressure inside is larger than outside

89
Q

What is in place to prevent negative differential pressure?

A

Negative pressure relief valves

90
Q

What is the ditching mode used for?

A

To isolate the cabin from water entering

91
Q

What happens in the pre-pressurisation mode?

A

The aircraft sets the cabin pressure higher than the ambient pressure to check for leaks

92
Q

What is the difference between internal and external climb/descent modes?

A
  • internal changes cabin altitude in proportion to ambient altitude
  • external is a preset that increases/decreases over time not altitude
93
Q

When would the external climb mode stop?

A

When the aircraft starts to make an unplanned descent

94
Q

When the external climb mode is interrupted, what is the cabin altitude set to?

A

The altitude of the take off airport

95
Q

What follows the climb phase?

A

The cruise phase

96
Q

When does the controller start the descent mode?

A

When the aircraft starts to descend

97
Q

When does the controller switch to ground mode?

A

When the air ground logic senses weight on wheels

98
Q

What happens to the controllers if the aircraft has two of them?

A

They switch after every flight

99
Q

How much difference in psi is there for a cabin pressure leakage test?

A

4psi

M11 R (21 decks)

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