What is required when operating the APU/ATM system in hangars without an automatic fire suppression system?

In the context of operating the Auxiliary Power Unit (APU) and Auxiliary Turbine Module (ATM) system in hangars that lack an automatic fire suppression system, the requirement for two 150 lbs HALON fire extinguishers along with a Crash Rescue Firefighting (CFR) vehicle on standby is crucial for ensuring safety in the event of a fire.

Halon extinguishers are specifically designed for use in aviation scenarios, including those in proximity to aircraft and fuel systems, as they are effective in suppressing flammable liquid fires and electrical fires—both of which could be a risk when operating APUs. The presence of two extinguishers ensures that there is sufficient backup in case one is used, as well as making it easier for firefighting personnel to access the equipment quickly from different locations within the hangar.

Additionally, having a CFR vehicle on standby signifies a proactive measure to provide immediate response capabilities in an emergency situation. This aligns with aviation safety protocols, which emphasize preparedness and rapid response to potential fires that could present significant hazards.

Collectively, these requirements reflect a comprehensive approach to fire safety in environments where traditional automatic systems are not available, thereby reducing risk and enhancing overall safety when operating sensitive equipment like the APU.