Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas DC-10-10 series airplanes. This proposal would require inspections of the wings to detect cracks in the aft spar lower cap, in certain stringer butterfly clips on the bulkheads, and in certain fastener holes; and repair, if necessary. This proposal would also require modification of those areas of the wings, which would terminate the repetitive inspection requirements. This proposal is prompted by reports indicating that, during fatigue testing of the wing structure, cracks developed in the aft spar lower cap, in certain stringer butterfly clips, and in certain fastener holes due to fatigue-related stress. The actions specified by the proposed AD are intended to prevent such fatigue-related cracking, which could lead to the failure of the aft spar cap and consequently could reduce structural integrity of the wing.