Action
Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
Summary
We are revising an earlier proposed airworthiness directive (AD), for all The Boeing Company Model 727 airplanes, which proposed to supersede an existing AD. That NPRM proposed to retain repetitive inspections of the in-tank fuel boost pump wiring, installation of sleeving over the in-tank fuel boost pump wires, repetitive inspections of a certain electrical wire, sleeve, and conduit, and applicable investigative and corrective actions; and repetitive engine fuel suction feed operational tests. That NPRM proposed to also require replacement of the wire bundles for the wing and center fuel boost pumps, installation of convoluted liners, and related investigative and corrective actions if necessary. That NPRM also proposed to require replacement of the fuel quantity indicating system (FQIS) wires; a low- frequency eddy current inspection for cracking; and repair if necessary. That NPRM also proposed to require revising the maintenance program to incorporate changes to the airworthiness limitations section. That NPRM was prompted by a report of damage found to the sleeve, jacket, and insulation on an electrical wire during a repetitive inspection. This action revises that NPRM by revising certain compliance times, specifying a terminating action, and adding a proposed requirement to incorporate another change to the airworthiness limitations section. We are proposing this supplemental NPRM to prevent chafing of the fuel boost pump electrical wiring and leakage of fuel into the conduit, and to prevent electrical arcing between the wiring and the surrounding conduit, which could result in arc-through of the conduit, and consequent fire or explosion of the fuel tank. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.