Federal Aviation Administration October 11, 2012 – Federal Register Recent Federal Regulation Documents

We propose to supersede an existing airworthiness directive (AD) that applies to all The Boeing Company Model 727 airplanes. The existing AD currently requires repetitive 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, and applicable corrective action; and installation of sleeving over the in- tank fuel boost pump wires. The existing AD also requires repetitive inspections for damage of a certain electrical wire and sleeve, and arcing damage of the conduit and signs of fuel leakage into the conduit; applicable investigative and corrective actions; and repetitive engine fuel suction feed operational tests. Since we issued that AD, we received a report of damage found to the sleeve, jacket, and insulation on an electrical wire during a repetitive inspection. This proposed AD would require replacement of the wire bundles for the wing and center fuel boost pumps with new, improved wire bundles, installation of convoluted liners, and related investigative and corrective actions if necessary. This proposed AD would also require replacement of the fuel quantity indicating system (FQIS) wires with new, improved wires; a low-frequency eddy current inspection for cracking; and repair if necessary. This proposed AD would also require revising the maintenance program to incorporate changes to the airworthiness limitations section. We are proposing this AD to detect and correct 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.