APU Flashcards
What requirement for starting the APU is associated with aircraft equipped with AHRS-900?
For aircraft equipped with the AH-900 AHRS system, do not start the APU until the AHRS 1-2 ALN advisory message is presented on the EICAS.
What is the minimum battery voltage for APU start?
19V
What electrical power sources are available for APU start?
- GPU
- Battery #2
- Battery #2 assisted by another generator online
What is a APU swing start?
If ignition is not detected at approximately 30% RPM during the start cycle, the starter generator is de-energized. When the APU decelerates to approximately 5% RPM, the starter is automatically re-energized for another start attempt. This automatic feature is referred to as ‘swing start’ and is limited to once per start attempt.
How much time must pass after the APU start before the APU Bleed Valve may be opened?
3 minutes.
Describe the proper APU shut down procedure?
Close APU bleed.
Press the STOP button, monitor deceleration to 0% RPM. At 0% RPM, select the APU master knob to the OFF position.
What controls the APU?
The APU has its own FADEC.
What will the APU shut down for automatically on the ground? In flight?
On the ground the APU will shut down for any malfunction.
In flight, the APU will shut down for anything not heat related.
What will occur if a fire is detected in the APU compartment while on the ground?
An automatic shutdown will occur 10 seconds after a fire is detected.
If the APU fails to start during refueling, what should be done?
Do not attempt another APU start until they are done fueling. Do not attempt to start the APU before fuel hose is disconnected.
After landing, once parked at the gate there is no GPU available. The APU is started to supply power to the aircraft. How long must the crew wait till the engine can be shut down?
To prevent serious overcurrents in the electrical system, engines must not be shutdown concurrently with starting the APU. A minimum one minute interval between those two procedures is required.
