Series Airplanes, and C-9 (Military) Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes, and C-9 (military) airplanes, that requires a one-time visual inspection to determine if all corners of the aft lower cargo doorjamb have been previously modified. This amendment also requires low frequency eddy current inspections to detect cracks of the fuselage skin and doubler at all corners of the aft lower cargo doorjamb, various follow-on repetitive inspections, and modification, if necessary. This amendment is prompted by fatigue cracks found in the fuselage skin and doubler at the corners of the aft lower cargo doorjamb. The actions specified by this AD are intended to detect and correct such fatigue cracking, which could result in rapid decompression of the fuselage and consequent reduced structural integrity of the airplane.