Based on the airworthiness certification needs of domestic transport aircraft

the changing history

the connotation and index requirements of CCAR/FAR25.981 were systematically analyzed. From the perspective of the model applicant

a preliminary discussion on the conformity methods to be adopted in the process of airworthiness certification was conducted. Meanwhile

the flammability indexes and conformity verification methods of different types of fuel tanks were summarized. Subsequently

the fuel tank flammability assessment application issued by Federal Aviation Administration（FAA） was studied. Research shows that: (1) the revision of airworthiness regulations is the result of the development of fuel tank safety technology and knowledge level

and the airworthiness regulations must be closely combined with the current mainstream technology level; (2) different types of fuel tanks allow different levels of fleet average flammability exposure

among which fuselage fuel tank is the focus of airworthiness certification; (3) the difficulty of the average flammability exposure time of the computer team lies in the accurate acquisition of the balance temperature difference and time constant

which can be solved through establishment of fuel tank thermal model and genetic algorithm tracking.