737 APU

  1. What does the APU power on the ground?
    In FLight?
    • It powers both generator buses.
    • only one generator in flight
  2. What is the max altitude for APU operations for:
    Bleed Air?
    Bleeds and Electrics?
    Electrical Load?
    • 17,000 feet
    • 10,000 feet
    • 35,000 feet
  3. Where is the Air Inlet door located?
    What is it used for?
    • Right side of tail.
    • used for compression and cooling.
  4. Where does the APU get its fuel from?
    • normally from tank one via APU shutoff valve.
    • APU DC fuel pump starts APu when no main tank pump.
  5. What does the APU control Unit Monitor?
    What is the APU load priority?
    • Monitors APU from Start to shutdown.
    • Electrics have priority over bleed supply.
    • too much load bleed air will be closed and electrics will have priority.
  6. Why is battery power needed for the APU?
    provides power for DC start motor, ignition and protection circuits.
  7. What type of APU do we have?
    Garrett GTCP85-129
  8. What does Blue APU Gen OFF BUS  mean?
    APU is onspeed and ready to supply bleed air and electrics.
  9. What does MAINT light mean?
    • loss of redundant component.
    • Maintenance action required.
    • Light is disarmed when APU is OFF.¬†
    • minor electrical fault or servicing.
  10. APU Fire switch does what?
    Where else is a fire switch?
    • immediately shuts down the APU .
    • There is a APU fire handle in the Right main Wheel well.
    • Automatically shuts down when fire sensed.
  11. How long do you oper before selecting bleed air?
    one minute.
  12. APU Limitations:
    Max EGT ?
    Max Cont EGT?
    Start Limits?
    • 760 C
    • 710 C
    • five minute cooling period between 2nd and 3rd attempts. after 3 consecutive starts a 60 min cool down.
  13. APU Bleed Air Limits
    APU Bleed Air valve must be closed when:
    • Engine No 1 bleed valve is open.
    • Isolation and engine NO 2 bleed valve open.
    • Ground Air connected and Isolation valve open.
  14. What does:
    AMBER low oil pressure?
    • illuminates during low oil pressure leading to autoshutdown.
    • Auto shutdown when APU control box senses overspeed. extinguishes when placed to OFF. will clear if it problem no longer exists.
    • indicates internal faults.
Card Set
737 APU
737 APU questions