Airworthiness Directive · Amendment 39-18661 · Fuel
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-400, 747-400D, and 747-400F series airplanes, certificated in any category, as identified in Boeing Special Attention Service Bulletin 747-28-2324, Revision 1, dated July 27, 2015.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, 747-400D, and 747-400F series airplanes. This AD was prompted by a determination that a certain fastener type in the fuel tank walls has insufficient bond to the structure, and an electrical wiring short could cause arcing to occur at the ends of fasteners in the fuel tanks. This AD requires the installation of new clamps and polytetrafluoroethylene (TFE) sleeves on the wire bundles of the front spars and rear spars of the wings. This AD also requires inspecting the existing TFE sleeves under the wire bundle clamps for correct installation, and replacement if necessary. We are issuing this AD to prevent potential ignition sources in the fuel tank in the event of a lightning strike or high-powered short circuit, and consequent fire or explosion.
Within 60 months after the effective date of this AD, do the actions specified in paragraph (g)(1) or (g)(2) of this AD, as applicable.
(1) For airplanes on which the modification specified in Boeing Special Attention Service Bulletin 747-28-2324, dated November 3, 2014, has not been done as of the effective date of this AD: Install new clamps and polytetrafluoroethylene (TFE) sleeves on the wire bundles of the front spars and rear spars of the wings, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-28-2324, Revision 1, dated July 27, 2015.
(2) For airplanes on which the modification specified in Boeing Special Attention Service Bulletin 747-28-2324, dated November 3, 2014, has been done as of the effective date of this AD: Do a detailed inspection of the TFE sleeves under the wire bundle clamps for correct installation, and replace the sleeves if not correctly installed, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-28-2324, Revision 1, dated July 27, 2015.
