Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 737-300, -400, and -500 series airplanes. This proposal would require, among other actions, a one-time detailed visual inspection of the fuel quantity indicating system (FQIS) wiring and fuel tubing on the inboard side of the right wing rib wing buttock line (WBL) 227 and on the aft side of stringer No. 13 to determine if clearance exists between the FQIS wire harness and the refuel tube and tube coupling, and to detect any loose or broken refuel tube clamp or bracket or chafing of the FQIS wire harness; and corrective actions, if necessary. This action is necessary to detect and correct chafing and to prevent electrical contact between the FQIS wiring and the surrounding structure, which, in conjunction with another wiring failure outside the fuel tank, could result in fire or explosion of the fuel tank. This action is intended to address the identified unsafe condition.