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M11 Resit > 11.4 > Flashcards

11.4 Flashcards

1
Q

What stage of the engine is bleed air usually taken from

A

Compressor

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2
Q

What two stages is air usually bled from the compressor

Which of these is low pressure and which is high pressure

A

5th (lp) (low stage bleed port) and 9th(hp) (high stage bleed port)

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3
Q

when’s low pressure air bleed air used

A

During takeoff climb and cruise

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4
Q

When’s hp air used

A

At low engine RPM during descent or anytime LP air is inadequate

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5
Q

Can the LP and HP bleed ports be opened at the same time.

A

No

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6
Q

What regulates the air pressure from the bleed ports

What do these also acts as

A

Pressure regulating valve and bleed air valve

Shut off valves through cockpit signals or auto by pneumatic controller

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7
Q

What happens to the efficiency of the turbine engine when air is bled

A

Reduced efficiency as it means there’s less air for combustion

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8
Q

What was made as a result of the disadvantages caused by bleeding air from the turbine engines

A

Independent cabin compressor (to prevent an increase in fuel consumption)

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9
Q

What powers the CAC

A

Three phase motor

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10
Q

How many CACs are on 787

A

2

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11
Q

Where do bleed loads place there largely demand

A

APU

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12
Q

Where does the apu compressor supply air to before being using for heating, anti ice and engine starting

A

Load compressor

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13
Q

What 3 methods does the apu use to supply air for air conditioning and cabin pressurisation

A

Bleed air extracted from the compressor section.
Bleed air extracted from a separate load compressor driven by the turbine power section.
Bleed air extraction from the compressor driven from the two-stage axial turbine.

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14
Q

What altitude is bleed air extraction from the apu usually limited too

A

22,000ft

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15
Q

What does the apu supply via to get to the air con packs

A

Bleed air duct

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16
Q

What size hose is used to attach the ground cart air supply to the ac pneumatic system

A

4 inch

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17
Q

What can the ground cart be used for

A

Pneumatic system troubleshooting

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18
Q

What can the ground cart be used for

A

Pneumatic system troubleshooting

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19
Q

What direction does the connection point for the ground cart air supply point

A

Away from ac

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20
Q

What’s adiabatic mean

A

Temp change without additional or removal of heat

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21
Q

What’s convection mean

A

Process in which heat is transferred by a large movement of fluid

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22
Q

What’s super heat

A

Heat energy added to a gas after complete evaporation

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23
Q

What’s latent heat

A

Heat that causes a change in state with no change in temp

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24
Q

What temperature range can air con systems provide air

A

21-27 degrees

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25
Q

What does the air con systems functions

A

Supply ventilation air
Supply heated air
Supply cooled air
Cabin Pressurisation
Equipment Cooling

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26
Q

What are the two types of air con systems

A

Air cycle machine (used in larger passenger ac)

Vapour cycle machines

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27
Q

What temp at psi does the ac bleed air arrive at the primary heat exchanger

What temp drop does the primary heat exchanger give

A

30-40psi

150 c

100 c

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28
Q

What happens to the air from the primary heat exchanger when it goes to the compressor

A

Increase in pressure and temp (usually +30-40 c)

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29
Q

Where does the air go after the compressor and why

A

To the secondary heat exchanger to remove the added heat from the compressor

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30
Q

Where does the air go after the compressor and why

A

To the secondary heat exchanger to remove the added heat from the compressor (drops 60-70 c)

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31
Q

Wheres the water from the water extractors go after removed from air

A

To spray nozzles into the ram air duct to improve cooling efficiency

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32
Q

What speed does the shaft for the turbine wheel, wheels of compressor and the fan (in RPM)

A

40,000-50,000rpm

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33
Q

What speed does the shaft for the turbine wheel, wheels of compressor and the fan (in RPM)

A

40,000-50,000rpm

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34
Q

What does the pack valve/ flow control valve do

A

Valve that regulates bleed air from the pneumatic manifold into the air cycle air conditioning system

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35
Q

How are pack/ flow control valves operated and controlled

A

Electrically controlled

Pneumatically operated

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36
Q

What are pack / flow control valves also referred to

A

Supply shut off valve

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37
Q

What type of valve is a pack valve

A

A Venturi type butterfly valve controlled by a solenoid

38
Q

How are pack valves shut

A

Spring loaded to shut unless operated pneumatically

39
Q

How are pack valves shut

A

Spring loaded to shut unless operated pneumatically

40
Q

What’s in place as a fail safe for the pack valve if electrical supply is is broken

A

Opens

41
Q

What does the manual override on the pack valve allow

A

For it to stay fixed in a closed position

42
Q

What’s the main function of the pack valve

A

Control the airflow to the cabin

43
Q

On the ground what’s the mass flow brought the pack valve

What’s the mass flow at 8,000ft

A

1.1kg/s

0.86kg/s

44
Q

How can ac aircraft conditioning systems save energy

A

By adjusting the amount of airflow t9 the amount of passengers on board

45
Q

What % of airflow does the cabin receive when the pack flow selector is in the…

Normal position
High position
Low position

A

Norm- 100%
Hi- +100%
Low- 80%

46
Q

What happens to pressure and temp as the air reaches the turbine

A

Pressure and temp goes down

47
Q

What are the two types of lubrication for the air cycle machine

A

Air lubrication

Oil lubrication

48
Q

What two functions does the condenser/reheated have

A

To heat the air so it’s given energy

To cool the air before it goes through the water collector

49
Q

What low temps can be reached in water separator

A

-50

50
Q

What’s bypass airs function

A

To keep the air temp around 35 deg FAREMHEIT

51
Q

What are trim air valves used for

A

Used in systems to Mix conditioned air and provide temp controlled air to cabin and flight deck

52
Q

What does the mix chamber/manifold do

A

Collects the temp controlled clean conditioned air from the packs and distributes the warm or cold air to the flight compartments

53
Q

What do the RAM air door/valves do

A

Control the quantity of outside ambient air that flows through the primary and secondary heat exchanger

This RAM airs purpose is to remove some of the hear

54
Q

When’s maximum ram air available through the ram air door/valve

A

Ground and take off

55
Q

What do the ram air doors do during flight and why

A

Modulate to reduce drag and ram air

56
Q

What type of ac used vapour cycle machines

A

Ones powered by reciprocating engines (piston)

Only suitable for piston engines as they do t produce RAM air

Sometimes turbine powered tooo

57
Q

What principle does the vapour cycle machine work on

A

Thermodynamics

58
Q

What’s heat energy

A

Energy transferred by a temp diff

59
Q

What’s heat energy

A

Energy transferred by a temp diff

60
Q

What’s important to remember about the way heat energy travels

A

One direction only

61
Q

If the pressure in water increases by 20 psi what temp will it boil at

A

107.8 c

62
Q

What’s the refrigeration process

A

Compression

Condenser

Receiver-dryer

Expansion

Evaporation

Repeat

63
Q

What’s the refrigeration process

A

Compression

Condenser

Receiver-dryer

Expansion

Evaporation

Repeat

64
Q

What two problems can water in the refrigerant of the vapour cycle machine cause

A

Water could cause ice and block the flow of the refrigerant around the system

Water and refrigerant can cause acid

65
Q

What does the thermostatic expansion valve do in the vapour cycle machine

A

Has an adjustable orffice that allows the correct amount of refrigerant through to obtain optimal cooling

66
Q

What are evaporators made of

A

Copper or alluminium tubing coiled into a compact unit

67
Q

What can reduce the efficiency of the heat exchange to the refrigerant

A

Ice on the evaporator

68
Q

What two uses does the compressor isolation valve have

A

It permits servicing the system with refrigerant.

It can isolate the compressor so the oil level can be checked and replenished without opening the entire system and losing the refrigerant charge

69
Q

What two uses does the compressor isolation valve have

A

It permits servicing the system with refrigerant.

It can isolate the compressor so the oil level can be checked and replenished without opening the entire system and losing the refrigerant charge

70
Q

What two uses does the compressor isolation valve have

A

It permits servicing the system with refrigerant.

It can isolate the compressor so the oil level can be checked and replenished without opening the entire system and losing the refrigerant charge

71
Q

What a distribution ducts made off

A

Light fibreglass material coated to prevent damage from moisture

72
Q

What’s important to remember about the distribution ducts changing temperatures depending on the temp desired for cabin

A

They will expand and shrink but without losing the pressure tight seals of the ducts

73
Q

What’s a percentage of cabin air is filtered and recirculated ans what’s a positive of this

A

50%

Saves fuel as engines only provide the other 50% of the air

74
Q

What’s a percentage of cabin air is filtered and recirculated ans what’s a positive of this

A

50%

Saves fuel as engines only provide the other 50% of the air

75
Q

What are airflow outlets designed to do to the airflow pattern

A

To make it circular and controlled

76
Q

What mode is selected when at cruise

A

Isobaric

77
Q

What’s the max permissible rate of change in cabin pressure

A

0.16 psi per min

78
Q

When are ground tests of the pressure system required

A

Perform initial proof pressure test.
When specified in the maintenance manual.
After actual or suspected system malfunction.
After repairs and modifications to the aircraft pressure hull.

79
Q

How much refrigerant should a good leak detector be able to detect it losing in a year

A

Less than 1/2 ounce a year

80
Q

How much refrigerant should a good leak detector be able to detect it losing in a year

A

Less than 1/2 ounce a year

81
Q

What two other ways are there to detect leaks other than a electronic leak detector

A

Soapy water and inspect for bubbles

Injecting leak detection dyes and observing where they force a leak

82
Q

When was r12 refrigerant banned and why

A

1980

Harmful to earths ozone layee

83
Q

What’s can be used to determine which pneumatic device is at fault in a pressurisation system

A

EICAS or ecam

84
Q

What type of fire detector is using for pneumatic ducting

A

Continuous loop

85
Q

When would a “overheat” warning for the pack be displayed in the flight deck

A

When it overheats (outlet temp more than 260 ) or when the outlet temp is more than 230 c (four times in one flight)

86
Q

What do the colours mean on the central warning panel (r, a, g, w/b)

A

Red-systems I’m crit condit ans requires immediate temp

Amber- requires timely attention or will do soon

Green- system ready t9 be used

White or blue- system is in use

87
Q

What do the colours mean on the central warning panel (r, a, g, w/b)

A

Red-systems I’m crit condit ans requires immediate temp

Amber- requires timely attention or will do soon

Green- system ready t9 be used

White or blue- system is in use

88
Q

At what cabin altitude is does the central warning system aler the crew of high cabin alt

A

10,000ft

89
Q

At what cabin altitude is does the central warning system aler the crew of high cabin alt

A

10,000ft

90
Q

What will happen on the 737 if the cabin alt goes above 10,000ft

How’s it kept below 8k feet

A

A warning horn

Aural warning system (attention getter)

91
Q

What alt did Boeing make some cabin alt in 2005

A

6,500ft

92
Q

What alt did Boeing make some cabin alt in 2005

A

6,500ft

M11 Resit (13 decks)

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