AMM Task 12-11-28-650-001-A General Refuel/Defuel Safety Procedures:
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(19) Auxiliary Power Unit (APU) starts or shutdowns are permitted during refuel/ defuel procedures. If it is necessary to operate the APU, the limits that follow apply:
(a) An APU start is not permitted during a refuel/defuel procedure if the APU has failed to start or an automatic shutdown has occurred.
(b) You must complete a normal APU shutdown if a fuel spill has occurred during the refuel/defuel procedure.
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