Material Flammability Standards
Interim Aviation Safety Recommendations on
Material Flammability Standards
Existing standards allow the use of flammable materials in the manufacture of certain aeronautical products. Because the most stringent fire tests today are reserved for seat cushions, cabin wall panels and other materials located in cabin areas, some of the most flammable materials in the pressurized portion of an aircraft tend to be located in hidden, remote or inaccessible areas. In these areas they have the potential to contribute to an uncontrollable in-flight fire.
Apart from sustaining or propagating fires, many flammable materials poseadditional hazards, including heat release, smoke generation and the emission of toxins. For most materials, there are currently no regulatory restrictions regarding permissible levels of these combustion byproducts. The most effective means to mitigate these additional threats is to prevent the use of any material that sustains or propagates fire.
The TSB believes that no material, regardless of its location, type or quantity, should be allowed in the manufacture of an aircraft if it can sustain or propagate a fire in progress. Therefore, the Board recommends that:
For the pressurized portion of an aircraft, flammability standards for material used in the manufacture of any aeronautical product be revised, based on realistic ignition scenarios, to prevent the use of any material that sustains or propagates fire. (A01-02)
Several airworthiness authorities, including Transport Canada (TC), the Federal Aviation Administration (FAA) and the European Joint Aviation Administration (JAA) are coordinating efforts on material flammability standards and have extensive programs and projects, underway or planned, related to the topics covered in these recommendations. The effectiveness of any action taken as a result of these efforts will depend upon a harmonized approach among the FAA, JAA and TC regarding their implementation. In a meeting October 5, 2001, TC, the FAA and the JAA confirmed their commitment to cooperate in the realization of the objectives of these recommendations.
TC agrees with the need to revise, based on realistic ignition scenarios, the flammability standards for materials used in the manufacture of aeronautical products that are installed within the pressurized portion of an aircraft. TC is working in conjunction with the FAA and the JAA to promote a harmonized approach on this issue.
The FAA has advised TC that they concur with this recommendation and that the agency is developing new test requirements for materials in inaccessible areas of the aircraft in order to bring the level of flammability of all materials to that proposed for thermal acoustical insulation. These test requirements will include wiring, ducting, shielding and foam and the test methods will be refined through the International Aircraft Fire Test Working Group. The FAA is also pursuing test procedures and enabling technology for ultra fire resistant interior cabin materials.
As these improved flammability test standards and increased fire-resistant materials become available the certification standards and screening tests developed in conjunction with the other airworthiness authorities will be incorporated in Canadian regulatory standards.
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