What is the function of the APU when on the ground during a fire event?

The Automatic Power Unit (APU) plays a critical role in fire suppression on the ground during a fire event by automatically discharging halon. Halon is a fire-extinguishing agent that is effective in rapidly suppressing flames and cooling the area. The APU's ability to automatically activate this system helps to quickly address fire incidents without requiring direct manual intervention from the crew, allowing them to focus on other critical actions during an emergency situation.

This automatic discharge is essential for enhancing safety and providing an immediate response to contain and mitigate fire risks while ensuring that the aircraft's systems remain operational if needed. The presence of an APU that effectively releases halon during a fire event significantly improves the overall safety protocols of an aircraft, thus underlining its importance in emergency situations.