Summary
We propose to adopt a new airworthiness directive (AD) for certain McDonnell Douglas Corporation Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87), and MD-88 airplanes. This proposed AD would require repetitive inspections for cracking of the lower rear spar caps of the wings, and related investigative and corrective actions if necessary. This AD would also require repetitive inspections of certain repaired areas. This proposed AD results from reports of cracking of the wing rear spar lower cap at the outboard flap and inboard drive hinge at station Xrs=164.000; the cracking is due to material fatigue from normal flap operating loads. We are proposing this AD to detect and correct such fatigue cracking, which could result in fuel leaks, damage to the wing skin or other structure, and consequent reduced structural integrity of the wing.