APU Flashcards
APU master sw FAULT
AUTO SHUTDOWN has occurred
APU AVAIL
The APU is running above 99.5% or 2 seconds after reaching 95%
The APU is ready to accept and support an electrical and/or pneumatic load.
What condition in the APU system would cause an external horn to sound on the ground?
FIRE
With both APU and EXT AVAIL lights on, which is powering the aircraft?
the APU
If possible, how would the APU be used if it has already started the cool down cycle?
APU master ON
Why is it important to wait 2 minutes after the APU AVAIL light goes out before switching off the batteries?
Battery power is required for 2 minutes for the APU flap to close.
* Not waiting may cause smoke in the cabin during the next flight.
Auto Shutdown
Some reasons for an auto shutdown are…
Fire (on the ground)
Flap closed
Overspeed
No acceleration
No light off
DC power lost during start
low oil pressure
high oil temperature
If one generator fails, what is the maximum altitude that you can start the APU?
FL 410
If the aircraft is in the emergency electrical configuration, what is the maximum altitude to start the APU?
FL 250
What does APU BLEED FAULT illumination indicate?
APU bleed leak
