E175 APU 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?
- BATT 2 powers the starter
- BATT 1 powers the FADEC and EICAS for monitoring
What is the fuel source for the APU?
- Right fuel tank
- Left fuel tank through the crossfeed valve
What fuel pump is used for APU start?
- Batteries ‘ON’ only DC fuel pump in right tank
- AC powered airplane 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 APU shutdown
- 1-minute cool down
- No pneumatics (electrics only for 1 minute)
Can the APU shutdown be cancelled?
Yes, by moving the START switch back to ‘ON’ before the 1-minute cool down is over
How is the APU shutdown 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 of the APU occur on the ground?
- Overspeed
- Underspeed
- FADEC critical fault
- Fire
- Overheat
- Low oil pressure
When will automatic shutdown of the APU occur in the air?
- Overspeed
- Underspeed
- FADEC critical fault
Can the APU be started after a critical fault?
No
Max Altitude for APU
FL330
