Analysis of Airworthiness Requirements on Amdt.25–132 of Limit of Validity to Preclude Widespread Fatigue Damage

摘要

This article introduces innovatory changes and background to inspections of WFD for transport category aircraft which have resulted in the amendment 25-132 of limit of validity (LOV), also indicates a proactive approach which should be taken to address WFD before WFD occurs.With regard to the amendment to regulations on WFD issued by FAA, this article analyzes and interprets the actions of the design approval holder(DAH) and the related compliance methods, focusing on the applicability of the new regulations to WFD and on the methodologies and processes for performing aircraft WFD evaluations which include the determination of inspection start points(ISP) and structural modification points(SMP), the establishment of limits of validity (initial limits and extended limits)，the establishment and revision of airworthiness limitations and Airworthiness Limitations section(ALS), the compliance for part 121 and 129 operators under new regulations, etc. Then a number of new research directions are presented in this article for domestic civil aircraft structure damage tolerance design and analysis for the present and the future.