APU System Flashcards
What kind of APU is on the aircraft?
Sundstrand APS 2300
Describe the APU
- Constant speed
- Single stage impeller with a 2 stage axial flow turbine
- Independent oil system
What controls the APU?
A dedicated FADEC
What battery is used for the APU start?
- -Battery 2 powers the starter
- -Battery 1 powers the FADEC and EICAS
What is the fuel source for the APU?
- Right Fuel Tank
- Left fuel tank through the cross feed valve
What fuel pump is used for APU start
- With Batteries only - DC fuel pump in right tank
- With AC power available - ACMP 2
- Right engine running ejector fuel pump
Will the APU shutdown automatically if speed and acceleration
rate isn’t reached in starting cycle time?
Yes
What does moving the APU start switch to “OFF” do?
- Initiates normal shutdown
- 1 minute cool down
- No Pneumatics (electrics only for 1 minute)
Can the APU shutdown be canceled?
Yes
By moving the start switch back to”ON”
before the 1 minute cool down is over
How do you shut down the APU immediately?
- APU “Emergency stop button”
- No 1 minute cool down period
What will happen if batteries are turned
off during the 1 minute cool down period?
APU will shut down immediately
When will automatic shutdown occur on the Ground?
FOUL FO
- FADEC critical fault
- Overspeed
- Underspeed
- Low oil pressure
- Fire
- Overheat
When will automatic shutdown occur in Flight?
- Overspeed
- Underspeed
- FADEC critical fault
Can the APU be started after a critical fault?
No
Maximum Start Altitude?
30,000’
