Summary
We propose to supersede Airworthiness Directive (AD) 2012-18- 05, which applies to 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 currently requires 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 proposed AD would allow certain actions as optional methods of compliance. We are proposing 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.