Sunday, May 1, 2016
Crash-Resistant Fuel Systems: Decades of Data, And Delay
|The U.S. Army heeded the lessons of early crashes, in which occupants survived impact but died in fires, and worked with the industry in the 1960s to develop crash-resistant fuel systems.
Photo courtesy of the U.S. National Archives and Record Admin.
The FAA publicly called for the formation of the Rotorcraft Occupant Protection Working Group on Nov. 5, 2015, and set a six-month deadline for its first task: reporting on its assessment of the costs versus the benefits of steps to increase the use of better safety measures in helicopters being built now under old type certificates. That deadline falls early this month.
“Data associated with fatal helicopter accidents and fatalities remains virtually unchanged” for the U.S. over the last decade, the FAA noted in forming the group. “If the occupant protection improvement rules are not incorporated in new production helicopters, there will be no meaningful reduction in the number of fatalities in helicopter accidents.”
(We examined the question of improved seats, cabin designs and occupant restraints in “The Price of Egress” in our March 2016 issue on page 42.)
In weighing the fuel-system question, the group could draw on decades of research showing how such systems could protect the lives of crewmembers and passengers involved in helicopter crashes that are survivable except for the outbreak of fire after impact.
Despite that evidence and the adoption of new FAA rules calling for improved fuel systems in civil helicopters type-certificated after early October 1994, few new helicopters on the U.S. registry have such systems. The FAA Rotorcraft Directorate estimates that only 16% of the U.S. fleet fully complies with the 1994 standards. (The revised rules are spelled out in Federal Aviation Regulations sections 27.592 and 29.592.)
The disparity between that estimate and the longstanding, widespread use of crash-resistant fuel systems in military helicopters compelled the group’s formation late last year. The U.S. Army required the use of such systems in its helicopters in 1970.
Negative publicity about that safety gap is driving changes that are overtaking the group’s work.
Members of the Air Medical Operators Assn., which represents major U.S. air ambulance operators, have committed to updating their fleets with crash-resistant fuel systems.
The latest revision of the Commission on Accreditation of Medical Transport Systems’ widely used standards “strongly” encourages air ambulance operators to use such systems in any purchased, leased or contracted helicopters they add to their operations. The commission noted that adding such systems is “a significant financial investment of a relatively simple technology that may have a profound impact on the patients we transport.”
In a related development, the Senate passed a bill reauthorizing operations of the FAA for two years and calls on the agency to “evaluate and update, as necessary, standards for crash-resistant fuel systems for civilian rotorcraft” within a year of its adoption into law. The bill still must clear the House of Representatives and be signed by President Obama.
|Some vendors, including Robertson Fuel Systems and Vector Aerospace, are developing retrofit crash-resistant fuel systems for popular helicopters like the AS350. Photo courtesy of Vector Aerospace|
The latest review of crash-resistant fuel systems’ use throughout the U.S. civil helicopter fleet stems from the National Transportation Safety Board’s investigation of helicopter accidents involving post-crash fires and fatalities. That was capped by its probe of the Oct. 4, 2014, crash of a Bell Helicopter Bell 206L1+ air ambulance in which a flight nurse and paramedic died from burns and other injuries. The pilot was injured severely. (A patient aboard also died, the NTSB said, but probably of an injury sustained before transport.) The aircraft was not fitted with a crash-resistant fuel system.
The NTSB said the crash showed “that the impact forces alone during certain helicopter accidents are survivable if a post-crash fire can be prevented or its severity reduced.” It called on the FAA to require that all new-build rotorcraft incorporate crash-resistant fuel systems “regardless of the design’s original certification date.”
The NTSB pointed to an October 1994 FAA research that it said reaffirmed two significant findings from a June 1985 study on rotorcraft crash dynamics. The first finding was that a large percentage of U.S. civil rotorcraft accidents were potentially survivable ones. The second was that the predominant hazard to occupant survival was a post-crash fire.