The crash-resistant standards for the fuel systems ofcivilian helicopters are not as effective in protecting passengers insurvivable crashes as stricter military helicopter standards, accordingto a study by researchers from the Johns Hopkins Bloomberg School ofPublic Health Center for Injury Research and Policy. The civilstandards may be less effective than anticipated when they wereestablished in 1994. This is the first study of its kind to determinethe effectiveness of the standards. The study is published in theAugust 2005 issue of Aviation, Space and Environmental Medicine.
Post-crashfires are the single most important hazard to survivors of helicoptercrashes. Even though crash-resistant fuel systems have been almost 100percent effective in survivable crashes of military helicopters,manufacturers and regulators of civil aircraft have been slow toimplement the technology in civil helicopters, explained Dennis F.Shanahan, MD, MPH, corresponding author of the study and an associatein the Johns Hopkins Bloomberg School of Public Health’s Department ofHealth Policy and Management. “In 1994, civil regulations wereimplemented. They were based on the military regulations, but are notas strict as the military requirements. They also applied only to newlycertificated helicopter models.”
The researchers examinedNational Transportation Safety Board data of civil helicopter crashesfrom 1982 to 2004. They compared Bell 206 helicopters withcrash-resistant fuel systems to Aerospatial-350 helicopters, which didnot have crash-resistant fuel systems. They also looked at Bell 206helicopters before and after crash-resistant fuel systems wereimplemented. The Aerospatial-350 helicopters, made after 1981, had thehighest proportion (11 percent) of crashes with post-crash fires. Fewerthan four percent of the Bell 206 helicopter crashes had post-crashfires. Early Bell 206 models had a higher risk of post-crash fire, whencompared to models built after 1982, which is the year Bell Helicoptervoluntarily implemented crash-resistant fuel system standards similarto the civil regulations that wouldn’t be formally mandated for another12 years.
Fuel containment and isolation of fuel from ignitionsources is critical to surviving a crash. Uncontained fuel turns into amist, which when exposed to an ignition source, produces a fireball,typically before the helicopter comes to rest. This makes it moredifficult for occupants to survive a crash.
“Post-crash fires area serious issue that doesn’t often get the attention it deserves. Weshould be doing everything possible to increase helicopter crashvictims’ chance of survival,” said Susan P. Baker, MPH, a professor inthe Bloomberg School of Public Health’s Department of Health Policy andManagement and Center for Injury Research and Policy.
Co-authors of the study are Mark S. Hayden, Dennis F. Shanahan, Li-Hui Chen and Susan P. Baker.
“Crash-ResistantFuel System Effectiveness in Civil Helicopter Crashes” was supported bya grant from the National Center for Injury Prevention and Control atthe Centers for Disease Control and Prevention.
Materials provided by Johns Hopkins University Bloomberg School of Public Health. Note: Content may be edited for style and length.
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