Summary
This document revises an earlier proposed airworthiness directive (AD), which would have superseded an existing AD that is applicable to McDonnell Douglas Model DC-9 and C-9 (military) series airplanes. The existing AD currently requires the implementation of a program of structural inspections to detect and correct fatigue cracking in order to ensure the continued airworthiness of these airplanes as they approach the manufacturer's original fatigue design life goal. The previously proposed action would have required, among other things, revision of the existing program to require additional visual inspections of additional structure. The previously proposed action was prompted by new data submitted by the manufacturer indicating that certain revisions to the program are necessary in order to increase the confidence level of the statistical program to ensure timely detection of cracks in various airplane structures. This action revises the proposed rule by deleting the requirement to perform certain visual inspections of Fleet Leader Operator Sampling (FLOS) Principal Structural Elements (PSE). The actions specified by this proposed AD are intended to prevent fatigue cracking that could compromise the structural integrity of these airplanes.