Airworthiness Directives; The Boeing Company 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

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires repetitive inspections for cracking of the lower rear spar caps of the wings, and related investigative and corrective actions if necessary. This AD also requires repetitive inspections of certain repaired areas. This AD was prompted by 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 issuing 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.