Operation of aircraft onboard engines and combustion heaters shall be terminated prior to commencing fuel service operations and shall remain off until the fuel-servicing operation is completed.
Exception: In an emergency, a single jet engine is allowed to be operated during fuel servicing where all of the following conditions are met:
- The emergency shall have resulted from an onboard failure of the aircraft’s auxiliary power unit.
- Restoration of auxiliary power to the aircraft by ground support services is not available.
- The engine to be operated is either at the rear of the aircraft or on the opposite side of the aircraft from the fuel service operation.
- The emergency operation is in accordance with a written procedure approved by the fire code official.