Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to McDonnell Douglas transport category airplanes listed above, that currently requires a one-time detailed inspection to determine if wire segments of the wire bundle routed through the feed-through on the aft side of the flight engineer's station are damaged or chafed, and corrective actions if necessary. That AD also requires revising the wire bundle support clamp installation at the flight engineer's station. For certain airplanes, this action would require a new revision of the wire bundle support clamp installation, and modification of a certain wire bundle. This action also would reduce the applicability in the existing AD. The actions specified by the proposed AD are intended to prevent chafing of the wire bundle located behind the flight engineer's panel caused by the wire bundle coming in contact with the lower edge of the feed-through, and consequent electrical arcing, which could result in smoke and fire in the cockpit. This action is intended to address the identified unsafe condition.