Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all de Havilland Model DHC-7 series airplanes. This proposal would require certain structural inspections, and repair, if necessary. This proposal is prompted by a structural re-evaluation, which identified certain significant structural items to inspect for fatigue cracking as these airplanes approach and exceed the manufacturer's original design life. The actions specified by the proposed AD are intended to prevent fatigue cracking in these areas which, if not detected and corrected in a timely manner, could reduce the structural integrity of these airplanes.