A93P0003-Aviation Safety Recommendations Crash Resistant Fuel Systems Bell 212 Fuel Fitting
In February 1991, as a result of the broken fuel hose in the Blue River occurrence, the TSB forwarded an Aviation Safety Advisory to TC suggesting that they assess the feasibility of replacing critical fuel fittings with frangible self-sealing fittings and valves, or more durable fittings (steel vice aluminum). It is understood that TC is now considering adopting the Federal Aviation Administration (FAA) Notice of Proposed Rule Making (NPRM) 90-24 concerning crash resistant fuel systems (including a requirement for self-sealing breakaway fuel fittings) for inclusion in TC’s Airworthiness Manual Chapters 527 and 529. This would be a positive step toward establishing a greater safety margin with respect to crashworthiness in new aircraft designs. However, under this NPRM, existing aircraft will continue to operate with fuel systems that are significantly less crash resistant that the proposed standard. The previously mentioned occurrences demonstrate the potential for fuel escaping from cracked fuel-line fittings in existing fuel systems.
The Board fully supports the initiatives contained in NPRM 90-24 as a means to enhance safety in the long term; however, the Board feels that additional measures must be sought to ensure an increased level of crashworthiness in existing fuel systems in operations where there is a high risk of roll-over, such as heli-skiing. With respect to the 90 degree aluminum elbow fuel fitting of the Bell 212, it is felt that a more robust fitting (steel), or protection or relocation of the fitting could lessen its susceptibility to damage in roll-overs. Therefore, the Board recommends that:
The Department of Transport promote the modification of the Bell 212 fuel system to enhance the crashworthiness of the aluminum elbow fitting on fuel line PN 70-009K090W317 or equivalents. A93-01
The Department of Transport assess the feasibility of incorporating more crash resistant fuel systems in all helicopters (of existing designs) manufactured in Canada and in all Canadian-registered helicopters employed in operations with a high risk of roll-over, such as heli-skiing. A93-02
Transport Canada Response:
Transport Canada has assessed the feasibility of incorporating improved crashworthy fuel systems in helicopters in response to a previous Transportation Safety Board advisory. The Department has submitted an issue paper to the Federal Aviation Administration (FAA) Aviation Rulemaking Advisory Committee (ARAC) to initiate a project for the retrofit to improved crashworthy fuel systems on helicopters.
After a review of the FAA Notice Proposed Rulemaking (NPRM) 90-24 concerning fuel system standards for new designs of rotorcraft, Transport Canada concluded that a reasonable retrofit for existing helicopters, regardless of the type of operation that the aircraft is employed in, should focus on fuel feed and vent lines and their associated fittings.
The ARAC Rotorcraft Subcommittee is considered to be the appropriate forum to assess the feasibility and scope of this retrofit program. This committee is under the sponsorship of the FAA and consists of representatives of government agencies, including Transport Canada and the European Joint Aviation Authorities (JAA), as well as the rotorcraft operators and manufacturers.
Transport Canada agrees with the recommendation that the fuel system of the Bell 212 model helicopter can be improved by using steel fittings and can assure the Board that a modification program has been started.
Bell Helicopter Textron Inc has issued a Product Change Authorization (PCA) to incorporate stainless steel elbows on new productioin model 212 and 412 helicopters and changed the design specifications to preclude the installation of aluminum elbows in future Bell designated helicopters. The company is considering what action to take about the fuel lines on existing model 212 and 412 helicopters.
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