APU Atlas Flashcards
Where are the indicators and controls for the APU fire protection system located?
On the control stand pedestal on the flight deck and external fire protection panel on the AFT side of the nose gear
If the battery switch is selected off on the ground how will that affect the running APU?
Shut down the APU after normal cool down cycle. It is important to remember that doing this will remove APU fire detection
Fuel for the APU is supplied by which tank?
Left main tank
During start where is the indication for the APU EGT found?
EICAS Status page
What does the continuous illumination of the APU RUN light indicate?
The APU is at operating speed, above 95%
What can the APU FAULT light indicate?
APU fuel valve NOT in commanded position
The APU fuel valve is in transit during the start sequence
Other faults in the system such as fire, overspeed, high EGT, low oil pressure or high oil temperature
What is the normal sequence of events when the APU selector is turned off?
The APU Bleed valve closes, then after the cool down cycle, then APU shuts down
What battery is needed to start and operate the APU?
Both the APU battery and the main battery
The APU selector is moved from OFF to START and released to ON. When does the starter engage?
When the inlet door has fully opened
How is APU fault detection circuitry reset?
Position the APU selector to OFF
The APU selector has been inadvertently moved to 0FF and the APU RUN light is still illuminated. Can the shutdown cycle be cancelled?
Yes, by moving the APU selector to START and back to ON
With the APU operating, what happens when the FAULT light illuminates?
The APU shuts down immediately
During the APU start sequence the RUN light will flash how many times? What does the signify?
Twice, signifying the APU is completing its built in system test
APU electrical power can be utilised up to?
43,100 feet
APU bleed air is available until what altitude?
17,000 feet
