The FAA is proposing to amend certain airworthiness regulations for fire protection of interior compartments on transport category airplanes. This proposal would convert those flammability regulations from detailed, prescriptive requirements into simpler, performance-based standards. This proposal would divide these standards into two categories: Those designed to protect the airplane and its occupants from the hazards of in-flight fires, and those designed to protect the airplane and its occupants from the hazards caused by post- crash fires. In addition, this proposal would remove test methods from the regulations and allow applicants, in certain cases, to demonstrate compliance either without conducting tests or by providing independent substantiation of the flammability characteristics of a proposed material. This action is necessary to eliminate unnecessary testing, increase standardization, and improve safety. This proposal includes conforming changes to parts 27, 29, 91, 121, 125, and 135.