Airworthiness Directives; Boeing Model 727 Series Airplanes

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T99-12-52 that was sent previously to all known U.S. owners and operators of all Boeing Model 727 series airplanes by individual telegrams. This AD requires a boost pump dry bay inspection to detect leakage of fuel through an arced- through conduit, and corrective action, as necessary. This AD also requires repetitive detailed visual inspections of the in-tank fuel boost pump wiring to detect chafing of the wire insulation, evidence of electrical arcing, or arc-through of the conduit wall on Model 727 series airplanes, and applicable corrective action; and installation of sleeving over the in-tank fuel boost pump wires as a method to protect the wiring from chafing. This action is prompted by reports of severe wear of in-tank fuel boost pump wiring, and arc-through of the surrounding conduit on two Model 727 series airplanes. The actions specified by this AD are intended to prevent fuel tank explosion resulting from arc-through of the fuel boost pump wiring conduits.