Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain McDonnell Douglas Model MD-11 and MD-11F airplanes. The existing AD currently requires a one-time inspection to determine if metallic transitions are installed on wire harnesses of the tail tank fuel transfer pumps, and to determine if damaged wires are present; and repair, if necessary. This proposed AD would require modifying the case grounding for the alternate fuel pump of the tail tank, the leak detection thermal switch grounding for the number 2 engine, and wire braid grounding in the empennage and number 2 engine inlet. This proposed AD would also remove one airplane from the applicability of the existing AD. This proposed AD results from reports that the wire assembly for the alternate fuel pump is missing a case ground wire, and the lightning protection wire braid for wire assemblies located in the empennage and number 2 engine inlet are grounded improperly. We are proposingthis AD to prevent insufficient grounding of the fuel pump, which in combination with an electrical failure within the fuel pump and a compromised electrical bond could cause a fuel tank ignition, resulting in consequent fire or explosion.