AD FAA-2020-0096

The FAA is superseding Airworthiness Directive (AD) 2016-07- 28, which applied to all The Boeing Company Model DC-9-81 (MD-81), DC- 9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes, and Model MD-88 airplanes. AD 2016-07-28 required repetitive eddy current high frequency (ETHF) inspections for any cracking in the left and right side center wing lower skin, and repair if any crack was found. This AD continues to require repetitive ETHF inspections for any cracking in the left and right side center wing lower skin, and repair if any crack is found. This AD also requires expanding the inspection area to include adjacent stringers with similar stress levels and to perform repetitive inspections with increased sensitivity for crack detection. This AD was prompted by a report of a crack at a certain stringer not addressed by AD 2016-07-28, and cracks at certain other stringers and associated end fittings, and skins in the center wing fuel tank where the stringers meet the end fittings addressed by AD 2016-07-28. The FAA is issuing this AD to address the unsafe condition on these products.