Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 and MD-11F series airplanes, that currently requires replacement of the existing terminal strips and supports above the main cabin area; and installation of spacers between terminal strips and mounting brackets in the avionics compartment; as applicable. This action would require replacing the applicable terminal strips in the avionics compartment with new terminal strips. This action also would require performing an inspection to detect arcing damage of the surrounding structure of the terminal strips and electrical cables in the avionics compartment, and repairing or replacing any damaged component with a new component. This proposal is prompted by reports of arcing between the power feeder cables and support brackets of the terminal strips on airplanes previously modified per the existing AD. The actions specified by the proposed AD are intended to prevent electrical arcing caused by power feeder cable terminal lugs grounding against terminal strip support brackets, which could result in smoke and fire in the main cabin or avionics compartment.