Abstract: This article summarizes a series of important actions and their relevant results to preclude widespread fatigue damage (WFD), and then analyzes some unsafe factors existing in present airworthiness standards addressing fatigue damage to preclude WFD for transport category aircraft. It points out as a result that the existing requirements and long-term reliance on available inspections may not be sufficient to maintain the continued airworthiness of an aircraft beyond its design service goal and that this may create an unacceptable risk of structural failure with related accidents, unless a proactive approach is taken to address WFD before it occurs. Innovatory changes to inspections of WFD have resulted in the amendment to WFD regulations. With regard to the draft amendment to regulations on WFD proposed by Federal Aviation Administration (FAA), this article analyzes and interprets the actions of the design approval holder 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 and structural modification points, the establishment of operational limits (initial operational limits and extended operational limits), the establishment and revision of airworthiness limitations, 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.

Key words: transport aircraft, widespread fatigue damage, airworthiness standard, method of compliance