Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9 and C-9 (military) series airplanes. This proposal would require repetitive inspections to detect fatigue cracking of the fuselage frames and longerons 16R and 17R above the forward lower cargo door; repair, if necessary; and modification of the fuselage frames and longerons, if necessary, and follow-on repetitive inspections to detect fatigue cracking of the skin adjacent to the modification. This proposal is prompted by numerous instances of fatigue cracking of the fuselage frames and longerons. The actions specified by the proposed AD are intended to prevent fatigue cracking of the fuselage frames and longerons 16R and 17R, which could result in reduced structural integrity of the airplane.