Airworthiness Directives; de Havilland DHC-6 Series Airplanes

This document clarifies information in an existing airworthiness directive (AD) that applies to de Havilland DHC-6 series airplanes that do not have a certain wing strut modification (Modification 6/1581) incorporated. That AD currently requires inspecting the wing struts for cracks or damage (chafing, etc.), replacing wing struts that are found damaged beyond certain limits or are found cracked, and incorporating Modification No. 6/1581 to prevent future chafing damage. The actions specified in that AD are intended to prevent failure of the wing struts, which could result in loss of control of the airplane. This document clarifies the requirements of the current AD by eliminating all reference to repetitive inspections. The AD results from several reports of wing strut damage caused by the upper fairing rubbing against the wing strut.