APU Flashcards
What happens during a normal APU shutdown?
- Pneumatic power is removed immediately
* Electrical power is removed after a 1 minute cool down period
Can the APU shutdown sequence be cancelled?
Yes, by turning the APU selector knob back to ON during the shutdown sequence
What happens during an emergency APU shutdown?
The APU fuel shutoff valve closes and the APU shuts down without a two minute cool down period
The APU can supply electrical power up to?
33,000 feet
The APU can supply bleed air for engine starting up to?
21,000 ft
The APU can supply bleed air for air conditioning and pressurization up to?
15,000 ft
Where is the APU supplied fuel from?
The right wing tank
Is it possible to supply fuel to the APU from the left wing tank?
Yes, via a crossfeed valve
What automatically controls and monitors the APU?
It’s own dedicated FADEC
To avoid unsuccessful attempt starts it is recommended to wait how long before starting the APU after the EICAS is energized?
30 seconds
Max APU starting altitude
30,000 ft
What battery is used for the APU start?
- BATT 2 powers the starter
* BATT 1 powers the FADEC and EICAS for monitoring
What will the APU automatically shut down for in flight?
- Overspeed
- Underspeed
- FADEC critical fault
How long until the APU is ready to receive electrical and pneumatic loads?
3 seconds after APU reaches 95%
Minimum battery voltage for an APU start?
22.5 v
