Halon Replacement for Aircraft Fire Suppression Systems

The objective of this program was to demonstrate the effectiveness and to determine the toxicity and associated risks of labile bromine compounds as halon replacements for suppression of engine nacelle and dry-bay fires in military aircraft. Tests performed during this program have shown that labile bromine compounds generally and phosphorous tribromide PBr3 in particular, are more effective than Halon 1301 for both engine nacelle and dry-bay fire extinguishment and have neither ozone depletion nor global warming potentials. Theoretical electronic structure calculations and experimental chemical kinetics investigations were performed to enhance the understanding of the chemical action of PBr3 fire suppression. Independent toxicity studies supervised by the tri-services toxicology laboratory ALOET at Wright Patterson Air Force Base, determined that PBr3 was neither mutagenic nor toxic to aquatic organisms. Additional data on the toxicological properties of PBr3 were acquired by ALOET including dermal irritation and acute and subchronic inhalation toxicity. These results formed the basis of their independent risk assessment, which concludes that use of PBr3 as a halon replacement is safe in normally unoccupied spaces such as engine nacelles or dry-bays.