Ignition of Aircraft Fluids on High Temperature Engine Surfaces

Ignitions of aircraft flammable fluids that result from contact with hot surfaces of an engine are influenced by the characteristics of the secondary cooling air and engine surfaces, ventilation rates of the nacelle engine compartment, direction and changes of direction of the cooling air, and changes in engine power while leakage is occurring. The temperatures of the engine surfaces are much higher in installations of the new generation high bypass-high compression ratio turbofan engines and magnify the hot surface ignition problem. The effects of these advanced technology engines on hot surface ignition of aircraft fuels and a petroleum-base hydraulic fluid were investigated under simulated flight conditions in a fire test program on a modified current turbofan engine installation. All hot surface ignitions occurred in the form of explosions of varying degrees of severity.