Research on Testing and Calculation Analysis of Cargo Bay Fire-Extinguishing Agent Concentration Based on Different Loading in Civil Aircraft

In the history of international aviation, there have been many fire accidents of the cargo compartment. To ensure that the fire is extinguished in time when the cargo compartment is on fire, and to ensure the safety of aircraft and personnel, the design of the cargo compartment fire extinguishing system needs to be verified according to CCAR 25. According to the AC851-1 guidance, the verification of the cargo compartment's fire extinguishing system design aims to test and calculate the concentration of fire extinguishing agents used for the C-class cargo compartment based on different loading conditions of civil aircraft. Through the flight test of the cargo compartment under a no-load condition, it can be seen that the concentration of fire extinguishing agents in the cargo compartment is higher than 5% in the initial phase, higher than 3% in the 39,000ft and 10,000ft level flight phase, and the entire flight test phase is maintained above the suppression concentration required by the test, which meets the system design requirements. The concentration of fire extinguishing agents in the cargo compartment under a no-load condition is calculated and analyzed according to the maximum load rate (full load), and the result is higher than the required 3% suppression concentration.