Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes. This proposal would require repetitive inspections to detect wire chafing of the left and right engine fuel shutoff valve wire bundles at Power Plant Station 278 on each engine strut, and repair if necessary. This proposal would also require repetitive replacement of three wire support brackets with improved wire support brackets. This proposal is prompted by reports that such wire support brackets failed due to fatigue, which subsequently caused the fuel shutoff valve wire to chafe and to experience a short circuit. The actions specified by the proposed AD are intended to prevent such conditions, which could result in either the possible ignition of fuel vapors in a flammable leakage zone or in the inability to stop the flow of fuel in the event of an engine fire.