Engine Bleed Air Flashcards
Schematic
Image
When is HP air used?
- Descent ( Lo Thrust )
When is IP air used? What does IP check valve do?
Takeoff, Climb, Cruise ( Hi Thrust ) * Prevents reverse flow air from HP section from entering IP section of compressor
Engine Bleed Air switches via system logic, control which valves?
- ENG bleed air valve - PRV - HP bleed valve * These 3 close when switch turned OFF
Function of PRV for?
Prevents damage to ducting and equip downstream by limiting bleed air pressure.
Engine bleed air SYS FAULT Light for?
- Overheat - Overpressure - HP valve OPEN w/commanded CLOSE - PRV open w/commanded CLOSE
What does bleed duct isolation (ISLN) VALVE light indicate?
Isolation valve position disagree w/switch position
What prevents system reverse air flow into engine compressor sections during engine start?
PRV close
What happens if engine start valve fails to close?
- PRV remains closed (No air out) - Engine bleed air valve remains closed (No air in) - NAI and TR no avail for engine
What two valves close in engine for bleed air overheat?
- PRV - HP Valve
What would prevent NAI operation when respective bleed air switch is ON?
- PRV failed closed - PRV closed due to overheat - Start valve not closed
How would you isolate bleed air duct section for bleed duct leak?
- Close the respective isolation valve - Close the engine bleed air valves
With L or R duct isolated, how would leading edge flaps extend?
Electrically in secondary mode for isolated side. Opposite side normally (20-45 sec). There will be momentary asymmetry.
How does an isolated L or R duct affect hydraulic systems?
Respective hydraulic demand pump 1 or 4 is turned OFF.
If you have the ENG BLEED switch OFF (thus the PRV is closed) what you could do to override system logic and OPEN PRV without turning ENG BLEED ON?
Turn ON the NAI * Won’t override if valves have failed or closed for overheat however
