Two fire safety researchers at the FAA William J. Hughes Technical Center recently received a U.S. patent for an invention that will provide earlier detection of fires in aircraft cargo holds.

Dave Blake and Richard Lyon of the FAA’s Fire Safety Branch developed a test that can simulate two types of fires that might develop in the cargo hold—a smoldering fire and a flaming fire. The two also developed a combustion test sample for testing cargo compartment fire/smoke detectors. This test sample generates heat, smoke and gases—the same mixture of combustion products that would typify a cargo compartment fire under flaming or smoldering conditions.

Fires in aircraft cargo holds are difficult to detect before they reach the stage where they endanger the aircraft. The fires can begin very slowly, generating gases with little or no flames, heat, or visible smoke. Most current cargo fire detectors are optical systems. They detect smoke, but by the time smoke is generated the fire has advanced, and the threat to the aircraft is greater. To improve detection, sensitivity levels are turned up on the detectors but result in frequent false alarms—about 200 for every real fire detected. A reliable detector for this early stage of fire development would provide valuable time and opportunity for the crew to make a safe landing.

This combustion sample should simplify the development of new cargo compartment fire/smoke detectors with multiple sensors that can detect early-stage fires and discriminate between real fires and nuisance alarm sources, enhancing safety for air travelers. To create the sample, Blake and Lyon combined a mixture of pellets of the plastics usually found in cargo compartments. They molded the pellets into small samples, with a heating element embedded in the center. When the heating element is energized, the pellets begin to smolder, generating the gases of an early-stage cargo fire. Increasing the power or adding a flammable liquid to the mix creates a late-stage flaming fire atmosphere.

For more information, contact Holly Baker, (609) 485-6253.