Bell Helicopter 407. File photo
A Bell Helicopter 407, operated by Air Methods, crashed near Stuttgart, Arkansas, Nov. 19. The NTSB preliminary report released Tuesday said the fatal accident ended with a post-impact fire.
According to the NTSB, the aircraft (N620PA) impacted terrain and killed the pilot and two medical crewmembers. The helicopter sustained substantial damage. The aircraft was registered to and operated by Air Methods under Part 91 as a positioning flight. The flight took place at night, operated on a company visual flight rules flight plan, the NTSB said. The flight originated from Pines Bluff, Arkansas, and was en route to pick up a patient in Helena, Arkansas.
Residents near the accident site reported hearing a “boom” and seeing a fire plume, the report said. The crash was located by local law enforcement on private property on the bank of a reservoir. A post-impact fire consumed “a majority of the fuselage,” the NTSB reported. All major aircraft components were at the crash site. The NTSB also added, “several bird carcasses were located in the wreckage of the helicopter.”
The helicopter was retained for further examination. There was no explicit mention of the fuel system in the NTSB’s preliminary report. And although the 407 was absent from an October FAA notice naming 17 helicopter variants fully comply with the latest standards for crash-resistant fuel systems, Bell said the model does have an FAA-compliant crash-resistant fuel system. This includes the exception for 27.952(b)(1) reflected on the Model 407 FAA Type Certification Data Sheet H2SW. "We are working with the FAA on the language of the bulletin," Bell told R&WI.
Included on the compliancy list was Leonardo's AW109S Power and AW109SP GrandNew, Airbus Helicopters’ EC120B, EC130T2, EC135 (all models), MBB-BK117C-2 and MBB-BK117D-2, as well as the AS350B3 with Safran Arriel 2D engine (or the AS350B3e) when modified under Supplemental Type Certificate SR03931NY, which was awarded to Airbus July 12. Bell’s 427, 429 and 505; Helicopteres Guimbal’s Cabri G2; Leonardo Helicopters’ AW139 (and AB139), AW169 and AW189; MD Helicopters’ MD600N; Robinson Helicopter’s R66; and Sikorsky’s S-92A were also compliant.
FAR Parts 27.952 and 29.952 became effective Nov. 2, 1994, but only applied to newly type-certificated rotorcraft. There was no requirement to incorporate them retroactively into helicopters type certificated before that date.
The changes were aimed at increasing the level of safety for a survivable crash by decreasing the likelihood of a post-crash fire or delaying its onset. The changes require features that minimize crash-induced fuel leaks and their contact with potential fuel ignition sources both during and after the crash, the FAA said, and increase the time occupants have available to egress before a post-crash fire could become critical.
This article has been updated to clarify that although omitted from the FAA's original notice, the Bell Helicopter 407's fuel system does comply with the FAA's latest crash-resistance standards.