Airworthiness Directives; The Boeing Company Airplanes

We are superseding Airworthiness Directive (AD) 2012-18-05 for The Boeing Company Model DC-9-10, DC-9-20, DC-9-30, DC-9-40, and DC-9- 50 series airplanes; and Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9- 83 (MD-83), DC-9-87 (MD-87), MD-88, and MD-90-30 airplanes; equipped with a center wing fuel tank and Boeing original equipment manufacturer-installed auxiliary fuel tanks. AD 2012-18-05 required adding design features to detect electrical faults and to detect a pump running in an empty fuel tank. Since we issued AD 2012-18-05, we have determined that it is necessary to clarify the actions for airplanes on which the auxiliary fuel tanks are removed. This new AD allows certain actions as optional methods of compliance. This AD was prompted by our determination that it is necessary to clarify the actions for airplanes on which the auxiliary fuel tanks are removed. We are issuing this AD to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.