APU Flashcards
When is the APU available?
> 99.5 % or 2 seconds after N is above 95%
Automatic shut down occurs:
High Oil Temp Overspeed Temperature (Hot EGT) Underspeed Overspeed Fire (on ground) No acceleration No Flame ECB Failure Slow-start *AOM 49.20.2
APU service ceiling
FL398
Max Altitude to supply electrical power
SFC - FL398
Max Altitude for APU start with battery only
SFC - FL250
Max Altitude for APU bleed (One Pack)
SFC - FL200
Max Altitude for APU bleed (Two Pack)
SFC - 15,000 FT
Max Altitude to start an Engine
SFC - 8,000 FT
What does the APU Fire PB do?
Shuts OFF APU without a cooling period
Why must you leave the batteries on after shutting down the APU and how long?
- To ensure Fire Protection until complete shutdown
- Ensure intake flaps close
- APU computer remains powered through shutdown
- APU scavenge oil to APU sump to prevent cabin fogging on subsequent starts
How do you know you’re using APU electrical power?
- An UP arrow from the APU SD page
2. Load is displayed on the APU SD page
How much time is required in order to push the START PB after MASTER has been pushed?
At least 5 seconds
APU is available when?
Approximately 1 minute after START PB pushed
AVAIL in APU SD Page
AVAIL displayed in START PB button
How much battery power is required if starting the APU with the battery only? And how much time do you have with the batteries to start?
At least 25.5 or greater
30 minutes
What condition in the APU system would cause an external horn to sound?
APU Fire
