APU Flashcards

1
Q

Pushing APU Emerg stop button

A
  • closes APU fuel shutoff valve

- shuts down APU without cooling period

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2
Q

Normal fuel supply for APU

A

Right wing tank via:

  • DC Pump when only DC power is avail
  • AC Pump when AC power is avail and engine not running
  • ejector fuel pump when engine is running
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3
Q

APU altitude limits

A

– Electrical AC power up to 33000 ft.
– Bleed air for engine starting up to 21000 ft.
– Bleed air for air conditioning and pressurization up to 15000 ft.
*Maximum altitude for APU start is 30000 ft.

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4
Q

Normal APU Shutdown sequence

A
  • rotate APU selector know to OFF
  • APU pneumatic power removed immediately
  • 1 or 2 minute cooldown period after which electrical power is removed

*EICAS message APU SHUTTING DOWN

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5
Q

Auto APU Shutdown on the ground

A
  • APU Fire
  • EGT overtemperature
  • High oil pressure
  • Low oil pressure
  • Sensor fail
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6
Q

Auto Shutdown of APU in flight

A
  • Overspeed
  • underspend
  • FADEC fault
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