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120-104 - Establishing and Implementing Limit of Validity to Prevent Widespread Fatigue Damage

Date Issued
January 10, 2011
Responsible Office
ANM-100,  Aircraft Certification Service, Transport Airplane Directorate
Description

This advisory circular (AC)offers guidance on compliance with Title 14 Code of Federal Regulations (14 CFR) 26.21, 26.23, 121.1115, and 129.115.  It tells design approval holders of transport category airplanes how to establish a limit of validity of the engineering data that supports the structural maintenance program (hereafter referred to as LOV) for those airplanes. It also tells design approval holders how to address maintenance actions that have been determined necessary to support an LOV.  It tells operators of those airplanes how to incorporate the LOV into their maintenance programs.  Finally, this AC provides guidance to anyone wishing to extend an LOV.  Guidance for establishing an LOV for airplanes whose type certificate was applied for after (XXXX) is contained in AC 25.571-1X.  Guidance for extending an LOV approved under § 25.571, § 26.21, or § 26.23 can be found here.  The actions described in this AC are meant to prevent widespread fatigue damage (WFD) in the transport airplane fleet up to the LOV.