During an APU fire, what initial action is recommended?

In the event of an APU (Auxiliary Power Unit) fire, the recommended initial action involves injecting the extinguishing agent into the fire. This step is crucial because it aims to suppress the fire quickly and effectively, minimizing damage and ensuring safety for personnel and equipment. Proper training emphasizes that the use of the fire extinguishing system should be the first response to contain the hazard before considering other actions.

Injecting the extinguishing agent directly targets the source of the fire, playing a vital role in emergency protocols. It is intended to control the fire as quickly as possible, which is critical in preventing the fire from spreading or causing more significant issues.

Other actions, such as shutting down the APU or opening the APU housing, can be considered but are secondary to the immediate need to suppress the fire. Activating the fire extinguishing system follows this initial response but does not specifically address the immediate action necessary to combat the flames.