APU + Fire Detection Flashcards
What does the APU supply on the ground?
- bleed air for starting engines and for the air conditioning system
- electrical power to the electrics system
What does the APU supply during take off?
bleed air for air conditioning
What does the APU supply in flight?
- backs up the electrical system
- backs up the air conditioning
- can be used to start the engines
How long should you wait between pressing the APU master switch and the ON switch?
3 secs for the flap to open
How can you shut down the APU immediately?
- Press the APU FIRE button
- Press the APU SHUT OFF button on the interphone panel under the nose fuselage
Where does the APU take the fuel from?
The left fuel feed line - fuel flow is controlled by the ECB
What is the APU ceiling?
The same as the aircraft ceiling - 39,800 ft
What does the ECB (electronic control box) do? (APU)
- sequences the start and monitors it
- monitors the speed and temperature
- monitors bleed air
- sequences the shutdown
- controls the automatic shut down
What happens if the ECB detects an APU fire on the ground?
It will shut down and the extinguisher bottle discharges automatically
What does the fire detection system consist of?
- two fire detection loops (A + B) mounted in parallel
- A fire detection unit (FDU)
on both engines and APU
What happens if both fire loops fail?
If they fail within 5 seconds of eachother you will get a fire warning
When will you get a fire warning?
- both loops A and B send a fire signal
- one loop sends a fire signal and the other has failed
- both loops break within 5 secs of eachother
- a test is performed on the FIRE panel
For how long can you press the APU fire test button when the APU is on?
three seconds maximum
How long is smoke detected for before warning in the avionics system?
5 seconds
How does air reach the APU compressor inlet?
the air intake and an electrically operated flap
