Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-100, -200, and -200C series airplanes. This proposal would require a one-time inspection for damage (i.e., chafing) of the power feeder wire bundle for the auxiliary power unit (APU) generator and the first officer's elevator down control cable and for proper separation between that wire bundle and control cable, and corrective action, if necessary. For certain airplanes, this proposal also would require attaching the power feeder wire bundle to adjacent wire bundles. This action is necessary to prevent a short circuit and resultant arcing between the wire bundle and control cable, which could sever the control cable. Failure of the first officer's elevator down control cable, if combined with a subsequent failure of the captain's elevator down control cable, could result in loss of elevator control of the airplane. This action is intended to address the identified unsafe condition.