Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model MD-11 and MD-11F airplanes. The existing AD currently requires inspecting to determine if wires touch the upper surface of the center upper auxiliary fuel tank, and marking the location, as necessary; inspecting all wire bundles above the center upper auxiliary fuel tank for splices and damage; inspecting for damage to the fuel vapor barrier seal and upper surface of the center upper auxiliary fuel tank; and performing corrective actions, as necessary. The existing AD also requires installing nonmetallic barrier/shield sleeving, new clamps, new attaching hardware, and a new extruded channel. The existing AD resulted from fuel system reviews conducted by the manufacturer. Since we issued that AD, we have identified additional center upper auxiliary fuel tank locations where inspections and corrective actions are needed. 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.