N25.1 General

• ED Decision 2009/010/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

N25.1 General ED Decision 2009/010/R (a) This appendix specifies the requirements for conducting fuel tank fleet average flammability exposure analyses required to meet CS 25.981(b) and Appendix M. This appendix defines parameters affecting fuel tank flammability that must be used in performing the analysis. These include parameters that affect all aeroplanes within the fleet, such as a statistical distribution of ambient temperature, fuel flash point, flight lengths, and aeroplane descent rate. Demonstration of compliance also requires application of factors specific to the aeroplane model being evaluated. Factors that need to be included are maximum range, cruise mach number, typical altitude where the aeroplane begins initial cruise phase of flight, fuel temperature during both ground and flight times, and the performance of an FRM if installed (See [AMC to appendix N, N25.1(a)](#_DxCrossRefBm1709821996)). (b) For fuel tanks installed in aluminium wings, a qualitative assessment is sufficient if it substantiates that the tank is a conventional unheated aluminium wing tank (See [AMC to Appendix N25.1(b)](#_DxCrossRefBm1709821998)). [Amdt 25/6]