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4. Systems > Pneumatics > Flashcards

Pneumatics Flashcards

1
Q

What systems require bleed air?

A

Air Conditioning

Wing Anti-Icing

Engine Starting

Hyd reservoir pressurization

Water pressurization

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2
Q

Where is the pressure supplied from?

A

Engine bleed
APU bleed or
External High Pressure ground connection

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3
Q

Bleed air is usually supplied from the Intermediate Pressure stage except for…

A

Idle conditions where the High Pressure stage supplies the bleed air.

Note: IP and HP bleed is never used at the same time

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4
Q

How is the bleed air cooled?

A

With a pre-cooler using cool air from the fan section

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5
Q

What is the max altitude for APU bleed?

A

20,000 feet

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6
Q

What side is the APU bleed connected to?

A

1 engine side, the crossfeed valve supplies APU bleed to both sides

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7
Q

What is unique about APU bleed air priority?

A

The APU has priority supplying bleed air

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8
Q

What is a limitation with the External High Pressure air connection?

A

When connected, DO NOT use any other bleed source!

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9
Q

Where are the leak detection loops?

A

APU ducting
Engine Pylon ducting
Wing ducting

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10
Q

What does BMC1 control?

A

Bleed air from Engine 1 and APU

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11
Q

What is special about the wing ducting?

A

There are 2 leak detection loops in the wings. Each monitored by different BMCs. Both loops must detect a leak for a pilot alert. Otherwise, the leak is automatically isolated.

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12
Q

Why would the Engine Number on the BLEED page be amber?

A

When the engine is below idele (off)

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13
Q

What happens to the associated PACK when you manually close an engine bleed valve?

A

Turning off the engine bleed valve automatically shuts off the associated Air Conditioning PACK.

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14
Q

How is the engine bleed valve closed by the pilot?

A

END BLEED pb OFF
OR
ENG FIRE pb engaged

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15
Q

Why would the BMC close the engine bleed valve?

A

Over temp

Over Pressure

Bleed Leak

Engine Start sequence

APU Bleed selected ON

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16
Q

How would Physics close the engine bleed valve?

A

No air pressure (spring loaded closed)

If reverse pressure is sensed

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17
Q

When will the auto X BLEED valve open?

A

When APU bleed is selected on.

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18
Q

What happens to the PACK control valve during engine start?

A

They automatically close to provide max pressure for engine start.

They will auto open ~30 seconds after start sequence

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19
Q

If a engine bleed fails during icing conditions, what is a limitation?

A

One engine bleed CAN NOT operate both PACKs when de-icing is on

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20
Q

During an engine bleed failure, can you use APU to supplement pressure?

A

NO, remember if you select APU bleed this will automatically close both engine bleed valves!

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21
Q

What is a icing limitation during a bleed air leak?

A

You CANNOT XFEED bleed air because of the leak as this will feed it the leak. Since you do not want to de-ice only one wing, you must depart icing conditions.

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22
Q

What 5 purposes has the Pneumatic System?

A

To provide compressed air as a source for:

  1. Air Conditioning
  2. Engine Starting
  3. Wing Anti Icing
  4. Water Pressurisation
  5. Hydraulic Reservoir Pressurisation.
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23
Q

What are the possible sources of Pneumatic Air?

A

Engine Bleed
APU Bleed
External HP Air

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24
Q

What are BMCs and how many are there?

A

Bleed Monitoring Computers
( or, sometimes, Bleed Management Computers, ‘Monitoring’ however is the official name.)

There are 2.

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25
Q

How are engine bleed valves signalled and operated?

A

Signalled electrically from the BMCs.

Operated pneumatically by upstream (i.e. engine side) Engine Bleed Air.

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26
Q

With the engine running, will the engine bleed valve Open?

A

Yes it will.

Unless electrically signalled Closed, or in order to prevent reverse flow.

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27
Q

What conditions will cause the BMC to signal the Bleed valve closed.

A
  • On-side engine starting
  • APU Bleed valve Open
  • downstream Overpressure or Overheat
  • Leak detected (in the Onside Wing or Pylon only.)
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28
Q

What other electrical signals will cause the Engine Bleed valve to be signalled closed?

A
  • Engine Fire p/b pressed
  • Engine Bleed p/b to OFF.
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29
Q

During Climb and Cruise, is Air bled from the IP or the HP stages of the engines?

A

IP.
The HP valve is only required when IP pressure is low and will maintain Bleed Pressure to 36+- 4 psi.

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30
Q

If the Engine Bleed valve is closed electrically, what happens to the HP Valve?

A

It too is electrically signalled closed.

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31
Q

To what pressure is bleed air controlled and by which component?

A

45+- 5 psi.

By the Engine Bleed Air Valve in its Pressure Regulating role.

32
Q

How is Bleed Air Temperature regulated and to what temperature?

A

A pre-cooler uses Fan Air to reduce the temperature of the bleed air to 200 deg C.

33
Q

How is the APU Bleed Air Valve signalled and operated?

A

Signalled OPEN electrically from either BMC

Operated pneumatically by Upstream APU Bleed Air Pressure.

34
Q

With the APU able to produce Bleed Air, but in the absence of any control signal, will the APU Bleed Valve open or close.

A

It will remain closed unless electrically signalled Open by a BMC.

35
Q

What conditions must be fulfilled before the APU Bleed Valve is signalled open?

A
  • Bleed Switch ON
  • APU speed > 95%
  • No leaks ( but this is ignored during engine start. )
36
Q

What is the effect on the pneumatic system when the APU Bleed Valve opens?

A
  • Cross-bleed Opens ( if in AUTO)
  • Both Engine Bleed Valves signalled closed.

Note: This action lies at the heart of Pneumatic System functionality:

APU Bleed Valve Open = X-Bleed Valve Open + Engine Bleed Valves Closed
APU Bleed Valve Closed = X-Bleed Valve Closed + Engine Bleed Valves Open.

37
Q

To which side of the Pneumatic System does the APU Bleed supply connect?

A

The Left side.

38
Q

In AUTO mode, APU Air in use, what will cause the X-Bleed Valve to be signalled closed?

A

Any leak detected (other than during engine start.)

39
Q

Which areas on the aircraft are monitored for Pneumatic Air Leaks?

A
  • Wing leading edge
  • Pylon (Engine)
  • APU supply duct.
40
Q

What will be the effect of a Left Wing Leak being detected?

A
  • FAULT light on Left Bleed p/b
  • Appropriate ECAM Caution
  • Left Engine Bleed signalled closed
  • APU Bleed signalled closed
  • X-Bleed signalled closed

NB: During engine start APU & X-Bleed Valves remain open until start complete, the Engine Bleed valve is closed anyway.

41
Q

What will be the effect of a Right Wing Leak being detected?

A
  • FAULT light on Right Bleed p/b
  • Appropriate ECAM Caution
  • Right Engine Bleed signalled closed
  • X-Bleed signalled closed

NB: During engine start X-Bleed Valve remains open until start complete, the Engine Bleed valve is closed anyway.
APU Bleed valve is unaffected by a Right Wing Leak.

42
Q

What is the effect of a Pylon (Engine) Leak?

A
  • Onside Bleed Valve FAULT light & ECAM Caution ( except during engine start.)
  • Onside Engine Bleed Valve signalled closed
  • X-Bleed signalled closed.
43
Q

What is the effect of an APU Duct Leak?

A
  • APU Bleed p/b FAULT light (and ECAM.)
  • APU Bleed Valve signalled closed (except during engine start.)
  • X-Bleed signalled closed (except during engine start.)

Note: Closure of the APU Bleed Valve will allow Engine Bleed Valves to open if Engine is running.

44
Q

If one BMC has failed, the other will take over monitoring functions.

However, what will happen to fault detection if BMC1 has failed?

A

Over-temperature, Overpressure of the Left Bleed Supply, & Left Wing Leak,
will be detected by BMC2 and an ECAM caution will be generated.

However, the FAULT light in the Left ENG Bleed p/b will not illuminate nor will the Left Engine Bleed Valve close.

In addition;
Neither a Left Pylon (engine) Leak nor an APU Duct Leak will be detected at all.

DSC-36-10-60

45
Q

What will happen to fault detection if BMC2 has failed?

A

Over-temperature or Overpressure of the Right Bleed Supply will be detected by BMC1 and an ECAM caution will be generated;
However, the FAULT light in the Right ENG Bleed p/b will not illuminate nor will the Right Engine Bleed Valve close automatically.

If a Right Wing Leak is detected, again, the ECAM message will be generated, but the Right ENG Bleed FAULT Light will not illuminate, nor will it close the Right ENG Bleed Valve automatically.

In addition, a Right Pylon (engine) Leak will not be detected at all.

46
Q

If a Bleed Valve FAULT light illuminates because of an Over-temperature and the Bleed Valve is switched OFF, will the FAULT light extinguish immediately?

A

No : only when the over temperature has disappeared.

47
Q

What is the single meaning of the APU Bleed FAULT light?

A

APU Leak detected.

48
Q

What are the positions of the X-Bleed Selector?

A

CLOSED
AUTO
OPEN

49
Q

Which side of the X-Bleed Valve is the Ground HP Connection?

A

Left

50
Q

When is the Ground HP Symbol ( a green triangle ) displayed?

A

Only on the ground.

51
Q

Is it permissible to use a combination of the APU and External HP Pneumatic Air to pressurise the Pneumatic System?

A

No.

Ref. LIM-21

52
Q

If an ECAM AIR ENG 1 BLEED FAULT caution is generated, is it necessary to switch OFF the associated Engine Bleed Switch, and what are the consequences of this fault?

A

The Bleed Valve p/b is to be switched OFF only if it does not close Automatically.

  • ONE PACK ONLY IF WAI ON
    One pack must be closed when the pilot is using wing anti-ice because of pre-cooler performance.
53
Q

If there has been a Wing or Engine Bleed Leak, what important consideration applies to the rest of the flight?

A

Avoid Icing Conditions

54
Q

Is it permissible to use External HP (note HP) Air for Air Conditioning?

A

Only if the Air Supply is confirmed to be free of Contamination.

Ref: FCOM PRO-SUP-21

55
Q

When using External Pneumatic Power for Engine Start, which engine is started first and what is the recommended start pressure?

A

Engine 1 normally, but can be either.

30 psi (with the start valve open.)

Ref: QRH SI 140

56
Q

Following the first engine start from External Pneumatic Power, how is the second engine normally started?

A

By the Cross-bleed Engine Start Procedure.

57
Q

When using the Cross-Bleed Engine Start Procedure;

What are the positions of the 4 Pneumatic System Valves?
What is the minimum recommended pneumatic pressure prior to start valve opening?
What maximum N2 must be observed?

A

APU Bleed - OFF
Engine Bleed Valves: Running Engine - ON, Receiving Engine - OFF.
X-Bleed Valve - OPEN.

Minimum Pressure prior to start : 30 psi
Maximum N2 : 80%

Ref: QRH SI 150

58
Q

The engines are the primary source of compressed air in flight.
Where is air bled from in the CFM engine?

A

IP air is bled from the 5th stage of the engine High Pressure compressor.

HP air is bled from the 9th stage of engine High Pressure compressor.

59
Q

In flight the APU can be used to supply bleed air to user systems up to what altitude?

A

20,000 feet.

60
Q

Where does the pneumatic system get its electrical power?

A

The DC system of the aircraft.

61
Q

Where are the BMCs installed?

A

In the avionics compartment.

62
Q

In normal flight BMC2 is powered by…?

A

DC2

It is unpowered in the emergency electrical config.

63
Q

On ECAM Bleed Page.

What does Cross-Bleed Valve in-line amber indicate?

A

The Cross-Bleed valve is not in the commanded (open) position.

64
Q

On the overhead panel, an amber fault light on the APU Bleed push button indicates?

A

BMC1 has detected an APU Leak.

65
Q

The engine bleed valve maintains what delivery pressure?

A

45 psi +/- 5 psi

66
Q

What is the design of the bleed air leak detection system?

A

A single loop for the APU & pylon.

A double loop for the wing.

67
Q

What happens to the cross-bleed valve if a BMC detects a leak in the bleed air system?

A

The cross-bleed valve will close, except during engine start.

68
Q

Within the engine bleed system, the Overpressure Valve will close when the bleed air pressure exceeds… ?

A

85 psi

69
Q

Where is the pre-cooler located on the engine bleed system?

A

Downstream of the Overpressure Valve.

70
Q

If both BMCs are faulty, ECAM will read;

“BLEED MONITORING FAULT”

and this will be accompanied by … ?

A

No master caution & no aural warning.

71
Q

If BMC2 fails, BMC1 takes over automatically but … ?

A

The ENG2 BLEED LEAK warning is lost, although

The APU BLEED LEAK warning remains available.

72
Q

A leak in the APU Bleed System would be detected by … ?

A

BMC1 only

73
Q

Above what N speed is bleed air usually available from the APU?

A

N > 95% (+2 seconds)

74
Q

How does the X BLEED work when selected to AUTO?

A

Opens the X BLEED valve if APU valve is open

Closes the X BLEED valve if APU bleed valve is closed, or an air leak is detected.

75
Q

What happens to the X BLEED valve if the APU FIRE button is pushed?

A

The X BLEED valve will close.

76
Q

Turning ON the ENG BLEED switch will open the bleed valve when?

A
  • Upstream pressure is > 8 psi
  • APU BLEED switch is OFF or APU bleed valve closed
  • There is no leak, over-pressure or over-temperature detected
  • ENG FIRE switch is not released out
  • Engine start valve is closed.

4. Systems (19 decks)

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