APU Flashcards
Which of the following statements is true?
Left FWD AC fuel boost pump is used when AC ground service power is available and APU DC fuel pump is used when no AC power is available
Which of these items is required for an APU start?
APU and; main batteries
Under what circumstances does no cooldown delay occur during the APU shutdown sequence?
If the bleed air valve is closed for more than 60 sec. before the APU selector is positioned to OFF
What happens to the APU FAULT light when the APU selector is placed to ON or START?
Illuminates until the fuel valve is open
What is the maximum altitude for operating the APU?
Airplane ceiling
What is the APU time delay feature for cooling?
Approximately 60 seconds after bleed valve has been closed (between 0 and 120 sec.)
APU selector is ON. APU FAULT amber light on the EICAS. FAULT amber light on the APU Selector Panel. What are the implications of these fault indications
General APU malfunction; APU shuts down
Which of the following describes the START position of the APU selector?
Momentary. Returns to ON when released
The APU selector has been inadvertently moved to OFF and the APU RUN light is still illuminated. How can the shutdown cycle be cancelled?
Move the APU selector to START and then release to ON
What can the APU FAULT light indicate?
APU fuel valve NOT in commanded position
What is the normal sequence of events when the APU selector is turned off?
The engine bleed air valves close, then after 60 seconds the APU fuel valve closes
How can an APU fault be reset?
Only by moving APU selector to OFF
The average APU fuel consumption is:
115 kg / h (ground) & 90 kg (flight)
What is indicated by an illuminated FAULT light when the APU selector is OFF?
Fuel valve did not close
The fuel for APU operation normally comes from which fuel tank?
Left main fuel tank
What is the minimum power needed to start and operate the APU?
APU battery and main battery
On ground, if you switch off the battery while the APU is running:
APU Shutdown with delay protection but without FIRE DETECTION
What does the APU FUEL VAL advisory mean?
The fuel valve is not in the signaled position
APU battery supplies power to:
Starter, air inlet door and APU control circuitry
When does the APU cool down timing delay begin?
When the APU bleed air valve closes
Why is a cooldown delay needed in the APU shutdown sequence?
To protect the APU from thermal shock.
APU is a single shaft gas turbine located in the unpressurized tailcone
True
What is cut off first when the APU selector is moved to OFF
Bleed air
No fire system test is required before starting the APU.
True
What does continuous illumination of the APU RUN light indicate?
APU is at operating speed.
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
Which is true statement regarding the APU?
The APU can supply electrical power for all normal loads plus bleed air for 2 air conditioning packs or start an engine
When will moving the battery switch OFF cause the APU to shut down?
On the ground only
