What safety actions are required if APU fire is detected on the ground?

• A. Shut off all aircraft systems and evacuate.
• B. Isolate the APU and wait for maintenance.
• C. Initiate aircraft fire procedures, shut off fuel supply to the APU, isolate the APU, and discharge extinguishing agent as directed.
• D. Continue operation to complete the mission.

Answer: (C)

When an APU fire is detected on the ground, the priority is to suppress the fire and remove its fuel source by following the aircraft’s emergency procedures. Shut off the fuel supply to the APU to stop feeding the fire, isolate the APU to cut off power and control connections that could keep the system energized or spread the fire, and discharge the extinguishing agent into the APU compartment as directed. This combination quickly stops the flame, limits damage, and keeps people safe while maintenance handles the aftermath. Continuing operation or delaying suppression would only feed the fire and increase danger, and evacuation is not the immediate step for an APU fire by itself unless another threat is present.