Airworthiness Directives; McDonnell Douglas Model DC-8-11, DC-8-12, DC-8-21, DC-8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and DC-8-43 Airplanes; Model DC-8-50 Series Airplanes; Model DC-8F-54 and DC-8F-55 Airplanes; Model DC-8-60 Series Airplanes; Model DC-8-70 Series Airplanes; and Model DC-8-70F Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas transport category airplanes, that requires an inspection to determine the material composition of the lower inboard auxiliary spar cap of the left and right wings. For certain airplanes, this AD also requires 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.