Airworthiness Directive · Amendment 39-17806 · Electrical power
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-400 series airplanes, certificated in any category, as identified in Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 series airplanes. This AD was prompted by reports of auxiliary power unit (APU) faults due to power feeder cable chafing. This AD requires detailed inspections for damage of the APU power feeder cables; replacing the clamps and installing grommets; and related investigative and corrective actions if necessary. We are issuing this AD to detect and correct chafing of the APU power feeder cables within a flammable fluid leakage zone, which, with arcing, could result in fire and structural damage.
Within 18 months after the effective date of this AD: Do a detailed inspection for damage (e.g., surface finish integrity, excessive wear or possible heat damage) of the APU power feeder cables within each wire bundle on the left and right sides of the bulkhead, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013; except as required by paragraph (h) of this AD. If no damage is found during this inspection, before further flight, replace the clamp(s) and install grommets, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013. Do all applicable related investigative and correction actions before further flight. Where Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013, specifies installation of a clamp having part number (P/N) TA025097L16, a clamp having P/N TA025097L() may be installed instead.
Note 1 to paragraph (g) of this AD: The parenthesis “()” designates different size clamps, to accommodate possible wire bundle diameter size differences.
If any damage is found during any inspection required by this AD, and Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013, specifies to contact Boeing for appropriate action: Before further flight, repair the damage using a method approved in accordance with paragraph (k) of this AD.
As of the effective date of this AD, no person may install, on any airplane, any wiring support clamp, except for part number TA025097L(), in those areas of the airplane identified in Boeing Service Bulletin 747-24A2360, Revision 2, dated October 2, 2013.
Note 2 to paragraph (i) of this AD: The parenthesis “()” designates different size clamps, to accommodate possible wire bundle diameter size differences.
