Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain de Havilland Model DHC-7 series airplanes, that would have required a one-time inspection to assess the adequacy of the clearance between various adapter plates and seal retaining angles on the fuselage side access panel, and modification, if necessary. That proposal was prompted by reports of incidents involving corrosion and fatigue cracking in commuter-class airplanes that are approaching or have exceeded their economic design goal. This action revises the proposed rule by requiring modification of both the forward and rear seal retention angles, regardless of whether damage is found. The actions specified by this proposed AD are intended to prevent degradation of the structural capabilities of the affected airplanes.