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Willys Flashing > 11.4 > Flashcards

11.4 Flashcards

1
Q

Where is air supply from the engines taken from?

A

Compressor stage 5 or 9

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2
Q

When is air supply from stage 5 of the compressor used?

A
  • low pressure
  • supplied from low stage bleed port
  • used during take off climb and cruise
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3
Q

When is stage 9 air taken from the compressors?

A
  • from the high stage bleed port
  • used during low rpm descent or anytime low pressure is innedequate
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4
Q

How is air pressure from the engine adjusted for use?

A

By being passed through the pressure regulating valve (PRV) or the bleed air valve (BAV)

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5
Q

What is the purpose of an independent cabin compressor?

A

Designed to prevent increase in fuel consumption

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6
Q

How are independent cabin compressors powered?

A

Accessory drive gear boxes or bleed air

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7
Q

How does a positive displacement (root type) blower function?

A

It takes an amount of air compresses it and delivers it to the cabin duct

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8
Q

How does the centrifugal cabin compressor function?

A

It’s an ‘air pump’ with a centrifugal impeller in the induction system of a reciprocating engine

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9
Q

Why does a centrifugal cabin compressor have a variable ratio drive mechanism?

A

Adapts to offset fluctuations

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10
Q

How does a turbo compressor function?

A

Engine power compresses air drawn from the 5th or 9th stage is mixed with outside air

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11
Q

When are APU’s used to supply air?

A

-to start turbine engines
-when ground air supply is not sufficient

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12
Q

What are the methods that an APU can supply air?

A

-extracted from the compressor
-from a separate load compressor
-extracted from the compressor from the two stage axial turbine

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13
Q

What is ground cart air supply and when is it used?

A

-a small jet engine
-used for when the APU cannot be run or is not functioning and the engines cannot run
-can also be used for fault identification without the expense of the engines or APU

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14
Q

What is the primary method of supplying cool air to the cabin?

A

Expansion of air as it passes over the turbine

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15
Q

What temperature range are most AC systems capable of making?

A

21-27 degrees

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16
Q

What are the two types of air conditioning systems used on aircraft?

A

-Air cycle machine for larger aircraft
-Vapour cycle machine for smaller aircraft

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17
Q

How does air cycle conditioning function?

A
  1. Bleed air enters
  2. The air enters the first heat exchange
  3. The air enters the second heat exchange
  4. Air enters the condenser
  5. The air enters the reheat
  6. The air enters the turbine
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18
Q

What does the pack control valve do?

A

It regulates air from the pneumatic manifold into the air cycle system

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19
Q

Who controls the shut off function on a pack valve?

A

-Fire handle
-Engine shaft
-pack switch

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20
Q

When an abnormal condition or overheat is detected what does the pack valve do?

A

Shut off

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21
Q

What does the failsafe function do on the pack valve?

A

The pack valve opens when electrical supply is lost

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22
Q

What happens to the pack valve if pneumatic power is not available?

A

An actuator spring closes the valve

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23
Q

What does manual override allow for in a pack valve?

A

For it to be fixed in the closed position

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24
Q

What does the pack valve ensure?

A

Volumetric flow is kept constant through Venturi tube monitoring

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25
Q

What can air conditioning supply requirements rely on?

A

Passenger number

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26
Q

How do primary and secondary heat exchangers function?

A

Ram air is mixed and has a cooling effect.
On the ground a fan is used

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27
Q

What is the function of the air cycle machine?

A

To cool air through a compressor and expansion turbine most of the heat is lost through expansion

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28
Q

What are the two types of air cycle machines used?

A

Oil lubricated
Air lubricated

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29
Q

What are the two functions of the reheated / condenser?

A

-to cool air in the air con pack and to allow moisture to collect
-to reheat the air adding energy powering the ACM turbine

30
Q

What is the purpose of the water separator and the way it works?

A

It separates water with a spinning motion

31
Q

What is the function of air cycle machine byapasses?

A

Takes air from bleed ports or heat exchanger to prevent formation of Ice

32
Q

What is the function of trim air valves?

A

Used in some systems to acurately adjust air temperature for the cabin

33
Q

What is the mix chamber/manifold?

A

It collects temperature controlled air and distributes it to the cabin

34
Q

What is RAM air door /valve?

A

Small scoop or door usually actuated to collect cool air

35
Q

What is the function of a Vapour cycle Air con?

A

Used in piston engines and is a common air con system

36
Q

What are the components of a vapour cycle machine?

A

-Refrigerant (the working fluid that goes from liquid to gas and back)
-condenser which releases heat to the environment
-compressor which compresses gas and raises the temperature
-expansion valve which liquid passes through causing a rapid drop in heat and expansion increase
-evaporator a low pressure low temp refrigerant which absorbs heat

37
Q

What it’s important to do when replacing refrigerant?

A

R12 and R13A should not be mixed or be used interchangeably
The common trade name is Freon

38
Q

Receiver/dryer function?

A

Removes contaminants and water as water in refrigerant causes the formation of acid and water can form ice

39
Q

What is the function of the thermal expansion valve?

A

It actuates to monitor cooling and prevents liquid from entering

40
Q

How is conditioned air distributed to the cabin?

A

-Through a series of ducts and ceiling vents
-some is air is directed to electronics systems
-the temperature is selected by crew
-each passenger has a gasper vent

41
Q

On the ground now can air conditioning be achieved?

A

Through a ground unit

42
Q

What is the function of recirculating fan?

A

It draws used air conditioning and reuses up to 50%

43
Q

What air pattern are air flow vents designed to distrubute?

A

Carefully controlled circular airflow patterns

44
Q

How does the ventilation system circulate air?

A

Only within each row not forward or aft

45
Q

What cabin pressure is maintained at cruise in feet?

A

8000ft or less

46
Q

At what pressure do crew and passengers require oxygen?

A

10,000ft crew
15,000ft passengers

47
Q

Which area on the aircraft are pressurised and unpressurised?

A

Pressurised
-cockpit and fwd and aft cabin
-fwd and aft cargo holds
Unpressurised
-radome
-nose undercarriage
-centre section and torque box
-main undercarriage bay
-tail cone

48
Q

What is the equation for cabin differential pressure?

A

Cabin pressure (PSI) - ambient pressure (PSI) = cabin differential pressure (PSI)

49
Q

What is the definition of cabin altitude, cabin vertical speed and differential pressure?

A

Cabin altitude = cabin pressure in aircraft
Cabin vertical speed = change in pressure in the cabin in feet per minute
Cabin differential pressure = the difference between the cabin pressure and the outside

50
Q

What features are essential in maintaining cabin pressure?

A

-compressible door seals
-grommets
-sealants

51
Q

What is isobaric mode?

A

Aims to hold the pressure in the cabin at a single pressure despite the changing altitude

52
Q

What is differential pressure?

A

Works to maintain a constant differential in pressure in line with changing altitude

53
Q

What is manual mode?

A

Only used in emergency
-cabin pressure is manually controlled the maximum cabin differential continues to operate

54
Q

What is the function of the outflow valve?

A

It opens, closes and modulates to control the correct amount of pressure in the cabin.
It operates pneumatically.

55
Q

What is the function of positive and negative safety valves?

A

Positive = if excessive differential occurs (8-10)psi it opens to relieve pressure
Negative = if excessive negative pressure occurs (0.5-1.0)psi then it will open to avoid damage

56
Q

What is the function of dump valves?

A

They are automatically operated or manually acting as emergency pressure relief valves

57
Q

What are the pressurisation gauges/ indications?

A

-cabin altimeter
-cabin rate of climb or vertical speed indicator
-cabin differential pressure indicator

58
Q

When taxiing what happens to pressurisation?

A

The aircraft is pre pressurised to a difference of 0.1% psi
To ensure a gradual safe increase in pressure

59
Q

In take off and climb what happens to pressurisation?

A

Proportional control

60
Q

During cruise what will occur to pressurisation ?

A

Isobaric control

61
Q

On descent and landing what will happen to pressurisation?

A

Proportional control with a difference of 0.1psi on landing

62
Q

What is the function of the cabin pressure controller?

A

It will maintain and adjust cabin altitude automatically through a combination of electronic and pneumatic means

63
Q

How effective is a vapour cycle leak detector?

A

It should measure 1/2 an ounce per year losses or less

64
Q

How can you detect a leak from refrigerant systems?

A

-apply soapy solutions to fittings
-injecting leak detection valves

65
Q

What is important when releasing vapour cycle system gasses?

A

R12 is illegal to be released due to damage to the ozone
R134A is is not illegal to release but it is harmful

66
Q

What are gauges used for in vapour cycle systems and what is their application?

A

Low up to 150psi
High up to 500psi

67
Q

What is the function of the servicing unit?

A

Captures gas

68
Q

What combination of gauges/ warning systems show a leak or overheat to flight crews?

A

-flight deck gauges
-overheat detectors
-bleed air monitoring systems

69
Q

What is a regulator fault?

A

-the bypass valve
-the ram air inlet
-the compressor outlet temp sensor
-the flow control valve

70
Q

What is the difference between a turbo compressor and an engine mounted compressor?

A

Turbines driven by air and engine mounted is driven by an accessory gear box

Willys Flashing (24 decks)

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