Part 10 Auxiliary Power Unit

  1. What are the methods used to start the APU?
    • The APU electrical power switch on the electrical power panel.
    • The start/stop switch on the APU control panel.
    • (REFERENCE: FCOM Volume 3 APU)
  2. What power source does the APU use for start?
    • Aircraft battery.
    • (REFERENCE: FCOM Volume 3 APU)
  3. What are the indications if the APU is started from the electrical panel?
    • Flashing AVAIL light on the electrical panel until N2 reaches 95%
    • Flashing ON light on the APU control panel.
    • (REFERENCE: FCOM Volume 3 APU)
  4. When will the APU electrical power be connected to the AC buses if the APU is
    started from the electrical panel?
    • Power is automatically applied to any AC bus that isn’t powered by its respective
    • generator.
    • (REFERENCE: FCOM Volume 3 APU)
  5. Where is the APU external fire control panel located?
    • Located in the fairing immediately behind the left wheel well.
    • (REFERENCE: FCOM Volume 3 APU)
  6. When AC power is not available, how is fuel provided to the APU for starting?
    • Fuel for starting is provided by a Battery Bus powered DC start pump in the # 2 main
    • tank.
    • (REFERENCE: FCOM Volume 3 APU)
  7. Prior to engine start after ignition is armed, what synoptic page can be selected to
    verify the APU is operating properly and what should the N1 now indicate?
    • Selecting the secondary engine page displays the APU N1, EGT, N2, and oil
    • quantity. N1 should be 100% after ignition is armed.
    • (REFERENCE: FCOM Volume 3 APU)
  8. Can pressing the APU electric switch stop the APU if the APU was started with the
    START/STOP switch on the APU control panel?
    • No.
    • (REFERENCE: FCOM Volume 3 APU)
  9. Which engine air system shares ducting with the APU?
    • The # 2 air system shares ducting with the APU and is used to supply air to the other
    • systems through the isolation valves.
    • (REFERENCE: FCOM Volume 3 APU)
  10. What does an illuminated “USE ENG AIR” switch on the overhead panel indicate?
    • The APU air is selected ON and the cabin differential pressure is greater than 1.5
    • PSI.
    • (REFERENCE: FCOM Volume 3 APU)
  11. What does the APU generator switch “OFF” light indicate?
    • The APU generator is on speed and there is a malfunction. Switch can be pressed
    • to reset APU generator control unit (one time) if electrical system is in MANUAL.
    • (REFERENCE: FCOM Volume 3 APU)
  12. During APU start with AC power not available the “FUEL” light illuminates on the APU control panel. What does this light indicate?
    • Fuel pressure is low.
    • The DC start pump is not supplying adequate pressure, or the APU fuel shutoff valve has failed to open.
    • (REFERENCE: FCOM Volume 3 APU)
  13. What are the limitations regarding APU operation in flight?
    • (a) Start altitude 25,000 feet or less
    • (b) Run altitude up to 30,000 feet
    • (c) Used for electrical use only in flight.
    • (REFERENCE: FCOM Volume 3 APU)
  14. What happens when the APU fire handle is pulled?
    • APU goes to emergency shutdown, the APU generator field is de-energized, the fire
    • bottles are armed, and the APU fuel valve is closed. If the Air System is in auto
    • mode, the # 2 engine bleed valve closes and the APU bleed valve will close.
    • (REFERENCE: FCOM Volume 3 APU)
  15. What happens to the APU bleed valve when the APU is shut down?
    • The APU bleed air valve closes when the APU is shutdown even if the APU BLEED
    • AIR switch is left ON.
    • (REFERENCE: FCOM Volume 3 APU)
  16. What does the fail light indicate?
    • A start is not possible and maintenance is required.
    • (REFERENCE: FCOM Volume 3 APU)
Card Set
Part 10 Auxiliary Power Unit