Auxiliary Power Unit Flashcards
corrected and verified
What is the range where the APU starter cut-out will occur?
46% on the ground and 46-60% in flight.
What are the APU starter limits?
Three attempts in a one hour with a two minute waiting period between each attempt
What will the APU automatic fire protection provide in flight?
Automatic shutdown of the APU, but not automatic discharge of the fire bottle.
Where does fuel to operate the APU come from?
The left collector tank via a dedicated 28 VDC APU fuel pump.
Prior to APU start the minimum battery voltage should be_______________.
22 volts on both batteries
The APU will not start if the RPM is rotating above what speed on the ground versus flight?
5 percent on the ground 12 percent in flight
The maximum altitude for starting the APU is ________. It can be operated up to _________.
37,000 feet/41,000 feet.
APU bleed air can be used in flight up to what altitude?
25,000 feet.
The APU can be used as a source of bleed air for the aircraft ice protection systems.
False
If the APU door is stuck open or its position is uncertain, what must be done? Also what is the reason?
Is there a way around the restriction?
Maintain a max airspeed of 220 knots.
To prevent APU from windmilling without proper lubrication and to ensure the APU RPM remains below 12 percent in the event it becomes necessary to start the APU in flight.
Yes normal speeds can be used if APU is running
The APU control system ensures that priority is given to ____________.
Electrical power
APU bleed air is controlled by modulating the
APU Load Control Valve (LCV)
What is indicated by the illumination of the PUMP Fail light?
the APU pump failed to energize
What is indicated by the illumination of the PUMP FAIL light?
the APU fuel shutoff valve is not in the commanded position
What is the primary purpose of the APU?
provide electrical power
will the APU shutdown on due to high oil temp or low oil pressure?
yes on the ground
No if in flight
If the APU shuts down on the due to fire will the bottle fire?
Yes on the ground
No if in flight
At what altitude will the surge control valve open?
17000
If the APU Pump fails will the APU continue to operate?
Yes but it cannot be restarted without the pump
What is the purpose of the LCV
the load control valve varies pneumatic load to ensure electrical power and 45 psi in the manifold
can apu bleed air be used by anti ice system?
no
What powers the APU door and what powers the ECU?
The APU battery provides power to the door and is secondary for the ECU. The main battery is the primary power source for the ECU
If the APU is left unattended can the ground crew shut it down?
Yes through the use of an APU shutoff switch on the forward nose or in the APU compartment
