Airworthiness Directive · Amendment 39-18634 · Powerplant
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-8 and 747-8F airplanes, certificated in any category, as identified in Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015.
We are superseding Airworthiness Directive (AD) 2013-24-12 for all The Boeing Company Model 747-8 and 747-8F airplanes. AD 2013-24-12 required repetitive ultrasonic or dye penetrant inspections for cracking of the barrel nuts and bolts on each forward engine mount, and related investigative and corrective actions if necessary. This new AD retains the requirements of AD 2013-24-12 and also requires installing new barrel nuts at the forward engine mounts; or identifying the part number of the barrel nuts, inspecting affected barrel nuts for gaps of the strut bulkhead and forward engine mount, and doing related investigative and corrective actions if necessary. This new AD also removes airplanes from the applicability. This new AD also requires revising the maintenance or inspection program, as applicable, to include a new structurally significant item. This AD was prompted by our determination that it is necessary to mandate the installation of new barrel nuts or new inspections to adequately address the unsafe condition. We are issuing this AD to detect and correct cracked barrel nuts on a forward engine mount, which could result in reduced load capacity of the forward engine mount, separation of an engine under power from the airplane, and consequent loss of control of the airplane.
This paragraph restates the actions required by paragraph (g) of AD 2013-24-12, with revised service information. For airplanes identified in Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015: Except as required by paragraph (h)(1) of this AD, at the time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013, do the inspection specified in paragraph (g)(1) or (g)(2) of this AD, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013; or Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015. Do all applicable related investigative and corrective actions before further flight. Repeat the inspection thereafter at the times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013. As of the effective date of this AD, use only Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015.
(1) Ultrasonic inspection for cracking of the barrel nuts on each forward engine mount, except as required by paragraph (h)(2) of this AD.
(2) Dye penetrant inspection for cracking of the bolts and barrel nuts. Whenever a dye penetrant inspection is done, all the bolts and barrel nuts on that engine mount must be removed and replaced with new or serviceable parts.
(1) Where Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013; or Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015; specify a compliance time “after the original issue date of this service bulletin,” this AD requires compliance within the specified compliance time after December 17, 2013 (the effective date of AD 2013-24-12).
(2) Where Appendix B of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013, and Appendix B of Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015, state that alternate instruments and transducers can be used, this AD requires that only equivalent instruments and transducers can be used.
(3) Where Appendix A of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013, and Appendix A of Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015, state to record flight hours and flight cycles, record the flight hours and flight cycles on the airplane and the flight hours and flight cycles for each engine since change or removal.
After any inspection required by paragraph (g) of this AD: Submit a report of the inspection results (both positive and negative), and return all cracked bolts and barrel nuts, at the applicable time specified in paragraph (i)(1) or (i)(2) of this AD. The report must include the information requested in Appendix A of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013, or Appendix A of Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015, except as required by paragraph (h)(3) of this AD. Both the report and all cracked bolts and barrel nuts must be sent to the address specified in Appendix A of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013, or Appendix A of Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015.
(1) For airplanes on which an ultrasonic inspection was done and no cracking was found, do the required actions at the time specified in paragraph (i)(1)(i) or (i)(1)(ii) of this AD, as applicable.
(i) If the inspection was done on or after December 17, 2013 (the effective date of AD 2013-24-12): Submit the report within 10 days after the inspection.
(ii) If the inspection was done before December 17, 2013 (the effective date of AD 2013-24-12): Submit the report within 10 days after December 17, 2013 (the effective date of AD 2013-24-12).
(2) For airplanes on which a dye penetrant inspection was done, do the required actions at the time specified in paragraph (i)(2)(i) or (i)(2)(ii) of this AD, as applicable.
(i) If the inspection was done on or after December 17, 2013 (the effective date of AD 2013-24-12): Submit the report and return all cracked bolts and barrel nuts within 10 days after replacing the bolts and barrel nuts with new or serviceable bolts and barrel nuts in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-71A2329, dated September 27, 2013; or Boeing Service Bulletin 747-71A2329, Revision 1, dated May 28, 2015.
(ii) If the inspection was done before December 17, 2013 (the effective date of AD 2013-24-12): Submit the report and return all cracked bolts and barrel nuts within 10 days after December 17, 2013 (the effective date of AD 2013-24-12).
A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current valid Office of Management and Budget (OMB) Control Number. The OMB Control Number for this information collection is 2120-0056. Public reporting for this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, completing and reviewing the collection of information. All responses to this collection of information are mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to the FAA at: 800 Independence Ave. SW., Washington, DC 20591, Attn: Information Collection Clearance Officer, AES-200.
At the applicable time specified in paragraph 1.E., “Compliance,” of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015, except as required by paragraph (o)(1) of this AD: Do the actions specified in paragraph (k)(1) or (k)(2) of this AD, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015, except as required by paragraph (o)(2) of this AD.
(1) Install new barrel nuts using the bootstrap installation method identified in Part 1 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015.
(2) Do a general visual inspection to determine the part number (P/N) of the barrel nuts at the forward engine mount. If any barrel nut P/N SL4081C14SP1 is installed, before further flight, do a general visual inspection for gaps of the strut bulkhead and forward engine mount to determine if the nut-by-nut method identified in Part 4 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015, can be used, and do all applicable related investigative and corrective actions. Do all applicable related investigative and corrective actions before further flight, including the nut-by-nut replacement identified in Part 4 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015. If the nut-by-nut replacement identified in Part 4 of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-71-2332, Revision 1, dated May 28, 2015, cannot be accomplished, install new nuts, in accordance with paragraph (k)(1) of this AD.
Within 30 days after accomplishment of the actions required by paragraph (k) of this AD, or within 30 days after the effective date of this AD, whichever occurs later: Revise the maintenance or inspection program, as applicable, to incorporate Structurally Significant Item (SSI) 54-50-003c specified in Boeing 747-8/-8F Airworthiness Limitations (AWLs), Document Number D011U721-02-01, dated September 2015.
Accomplishment of the actions required by paragraphs (k) and (l) of this AD terminate the requirements of paragraphs (g) and (i) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
