2.9. Auxiliary Power Unit

[If your aircraft is not equipped with an auxiliary power unit delete this section.]

[If your aircraft auxiliary power unit is approved for use in flight, or if it can be used in flight but is not authorized for use in flight, insert the applicable information here and in the other chapters of the SOPs.]

[If the AFM for your aircraft specifies that operation of the auxiliary power unit requires human presence include that requirement in this section.]

[There are essentially two options for organizing checks for APU operation. The first is to include the required actions for start, operation and shutdown only in one section of the SOPs Checklists and then refer to that section in other areas. For example, the start of the APU as part of an After Landing Check could refer to the APU start check that is found in the Pre-flight chapter. The second option is to repeat the relevant portion of the APU checks in the respective checklists parts. You should choose whichever option best suits your operation. In these generic SOPs we have chosen option one and have located the checks in only one place and then referred to them throughout the SOPs and checklists.]

Whenever the Auxiliary Power Unit is used the following checks shall be used for start, operation and shutdown. Although the APU checks are designated to be completed by the PNF, if two crewmembers are available, it is recommended that the checks be carried out as "Challenge and Response" procedures.

APU START CHECK (PNF)
  • Batteries - ON
  • External Power - a/r
  • A/COL Lights - RED
    • To warn personnel that the APU is operating, the anti-collision lights must be at red or white whenever the APU is running.
  • APU MSTR Press - On
    • It will be necessary to wait approximately ___ seconds for the inlet door to open. Wait until the "INLET DR" annunciator extinguishes before starting the APU.
  • APU START Switchlight - Press
    • The APU start switchlight must be pressed for at least one second. An inadvertent selection lockout feature will prevent APU start if the switch is pressed for less than 0.5 second.
  • RUN annunciator - RUN (within ___ sec)
APU AFTER START CHECK (PNF)
  • APU GEN - Press GEN
    • The "GEN" annunciation will illuminate if the generator is serviceable. If it does not illuminate operation of the APU for bleed air is permitted.
  • APU BLD AIR - Press BLD AIR (after ___ sec)
    • It is necessary to wait at least ___ sec. after the APU "RUN" annunciator illuminates to ensure stabilization of APU intake air before selecting the APU bleed air on.
APU SHUTDOWN CHECK (PNF)
  • Batteries - ON
  • External Power - a/r
  • APU GEN - Off
  • APU BLD AIR - Off
  • APU MSTR or OVRSPD TST - Press
    • The APU may be shutdown using either the master or the overspeed test. The overspeed test should be used at least once every ___ hrs. of APU operation. When shutdown is done using the overspeed test it will be necessary to select the APU MSTR switchlight to off to close the inlet door.

 
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