Engine Bleed Air - Question Bank

Question 1

Under what conditions would High Pressure (HP) air be used?

Answer 1

• Descent

- Other low power setting operations

Question 2

Under what conditions would Intermediate Pressure (IP) air be used?

Answer 2

-High power setting operations

Question 3

The Engine Bleed Air Switches control which valves by system logic when bleed air pressure is available?

Answer 3

• Engine bleed air valve
• PRV
• HP bleed valve

Question 4

Describe the general function of the Pressure Regulating Valve (PRV).

Answer 4

The PRV limits bleed air pressure to prevent damage to ducting and other equipment downstream

Question 5

How are the engine bleed air valves actuated?

When do they open for forward flow?

Answer 5

• Bleed air valves are pressure actuated

- They remain closed until engine bleed air pressure causes forward flow

Question 6

With the HP valve failed open and the respective bleed air switch OFF, will nacelle anti-ice be available?

Answer 6

No

Question 7

An Engine Bleed Air System (SYS) FAULT light indicated what?

Answer 7

• Bleed air overheat
• Bleed air overpressure
• HP bleed valve open when commanded closed
• PRV open when commanded closed

Question 8

What does a bleed duct isolation (ISLN) VALVE light indicate (amber)?

Answer 8

-Isolation valve position disagrees with switch position

Question 9

What prevents reverse air flow into the engine compressor sections during engine start?

Answer 9

-the PRV is positively closed

Question 10

What happens if the engine start valve fails to close?

Answer 10

• Bleed air is isolated from the engine starter
• The PRV remains closed
• Engine bleed air valve remains closed
• Nacelle anti-ice and thrust reverse are not available for the respective engine

Question 11

What two valves close in the engine if a bleed air overheat is detected?

Answer 11

• PRV

- HP Valve

Question 12

What conditions in the engine bleed air system would prevent nacelle anti-ice operation when the bleed air switch is ON?

Answer 12

-PRV has failed closed
OR
-PRV has been closed due to a bleed air overheat
OR
-Start valve is not closed

Question 13

How would you isolate a bleed air duct section in the event of a bleed air duct leak detected?

Answer 13

• Close the respective ISLN valve

- Close the engine bleed air valves

Question 14

Do we normally operate with the Isolation Valves open or closed?

Answer 14

Open

Question 15

If the center duct is isolated, how is temperature controlled in all temperature zones?

Answer 15

• All temp zones operate in a backup temp control mode

- Trim air is unavailable

Question 16

With a left or right duct isolated, how would the leading edge flaps extend on the affected side, and what EICAS Advisory message would display?

Answer 16

• Respective LEF operate electronically in secondary mode

- FLAPS PRIMARY (until LEF extended)

Question 17

How does an isolated left or right duct affect the hydraulic systems?

Answer 17

Respective demand pump 1 or 4 is turned off

Question 18

What two systems use engine bleed air downstream in the engine prior to the engine bleed valve?

Answer 18

• Nacelle anti-ice

- Thrust reverse