The strategy of widespread fatigue damage in FMP system
Metallic structure fatigue has been regarded as a significant threat to the continued airworthiness of large transport category airplanes.Consequently,the current aircraft design has put forward requirements for fatigue monitoring.These requirements however not only remain static but also evolve with the application and variation of the aircraft structures.As we known,widespread fatigue damage (WFD) is a common phenomenon of aging aircrafts being a negative impact on safety and reliability of aircraft.The current FAR 25.571(b) requires that An LOV must be established(....),during which it is demonstrated that widespread fatigue damage will not occur in the aircraft structures.and FAA issued AC 91-82A in August 2011 providing guidance on developing and implementing a Fatigue Management Program (FMP) system to address in-service issues for metallic fatigue critical structure.This action brings new challenges to aircraft manufacturers in China.Section 2 in the paper briefly introduces the problem of widespread fatigue damage including the MSD and MED and the differences between them.Section 3 describes the steps to establish the LOV/ELOV and indicates a proactive approach which should be taken to address WFD before it occurs.With the regulation on WFD issued by FAA,this paper interprets the methodologies for performing aircraft WFD evaluations including the determination of inspection start point(ISP)and structural modification point(SMP).Then the management indexes to address WFD are proposed in section 4,such as the character of the material used to produce structures; when identifying the WFD-susceptible structures what should be considered; the interval of the inspections; the proper inspection methods and so on.Finally in Section 5 some suggestions on the management of WFD are proposed.More structural fatigue tests should be implemented in the design period to identify the WFD-susceptible structures.Accumulation of service experience of existing aircrafts should be made.Although some theories for a single crack have been formed well,there is lack of effective theoretical analysis methods on WFD because of lack of tests data and models.It is reasonable that developing and implementing the management indexes to address WFD which are involved in the FMP system may provide guidance on the estimation and management to address WFD for the present and future aircrafts.
K.Zhao S.N.Wang
School of Aeronautics,Northwestern Polytechnical University,Xian 710072,China
国际会议
International Conference on Airworthiness & Fatigue -7th ICSAELS Series Conference(大飞机安全性能与疲劳国际会议)
北京
英文
171-171
2013-03-24（万方平台首次上网日期，不代表论文的发表时间）