Airworthiness Directives; McDonnell Douglas Model DC-9-14 and DC-9-15 Airplanes; and Model DC-9-20, DC-9-30, DC-9-40, and DC-9-50 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain McDonnell Douglas Model DC-9-14 and DC-9-15 airplanes; and Model DC-9-20, DC-9-30, DC-9-40, and DC-9-50 series airplanes. This AD requires repetitive high frequency eddy current inspections to detect cracks in the vertical radius of the upper cap of the center wing rear spar, and repair if necessary. This AD is prompted by reports of cracks in the upper cap of the center wing rear spar that resulted from stress corrosion. We are issuing this AD to detect and correct cracking of the left or right upper cap of the center rear spar, which would cause a possible fuel leak and structural failure of the upper cap, and result in reduced structural integrity of the airplane.