Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas airplanes. This proposal would require an inspection to determine the material composition of the auxiliary spar cap of the lower inboard of the left and right wings. For certain airplanes, this proposal also would require repetitive detailed and dye penetrant inspections for cracking of the spar cap, and corrective actions if necessary. This action is necessary to detect and correct stress corrosion cracking of the auxiliary spar cap, which could cause excessive loads to the structure attaching the support fitting of the main landing gear (MLG) to the wing, and result in loss of the MLG. This action is intended to address the identified unsafe condition.