Airworthiness Directive · Amendment 39-18396 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-200C, -200F, -400, -400D, and -400F series airplanes; certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014.
We are superseding Airworthiness Directive (AD) 2010-26-10, which applied to certain The Boeing Company Model 747-200C, -200F, - 400, -400D, and -400F series airplanes. AD 2010-26-10 required repetitive inspections for cracking of the lap joints, modification of certain lap joints, and certain post-repair inspections of the lap joints. This new AD adds new repetitive post-modification inspections for cracking in the lap joints, and repair if necessary. This AD was prompted by an evaluation by the design approval holder (DAH) which indicated that certain lap joints are subject to widespread fatigue damage (WFD). We are issuing this AD to detect and correct fatigue cracking in certain lap joints, which could result in rapid depressurization and consequent reduced structural integrity of the airplane.
At the applicable time specified in Table 1 and Table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, except as required by paragraph (j)(1) of this AD: Do eddy current inspections for cracks in the skin of the lap joints, and do all applicable repairs, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, except as required by paragraph (j)(2) of this AD. Do all applicable repairs before further flight. Repeat the applicable inspections thereafter at intervals not to exceed those specified in Table 1 and Table 3 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014.
At the applicable time specified in Tables 2, 4, 5, and 6 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, except as required by paragraph (j)(1) of this AD: Modify the applicable lap joints, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, except as required by paragraph (j)(2) of this AD. Accomplishment of the modification required by this paragraph terminates the repetitive inspections required by paragraph (g) of this AD for the length of the modified lap joint.
At the applicable time specified in Tables 7, 8, 9, and 10 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, except as required by paragraph (j)(1) of this AD: Do the applicable inspections specified in paragraph (i)(1), (i)(2), or (i)(3) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014. Repeat the applicable inspections thereafter at the applicable times specified in Tables 7, 8, 9, and 10 of paragraph 1.E, “Compliance,” of Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014. If any crack is found during any inspection, repair before further flight using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
(1) For airplanes identified as Groups 2 through 5 and 8 through 10 in Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014: Internal detailed and surface high frequency eddy current (HFEC) inspections for any crack in the skin or internal doubler.
(2) For airplanes identified as Groups 6, 11, and 19 in Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014: External detailed and low frequency eddy current inspections of the upper and lower skin panels for cracking, external detailed and HFEC inspections of the doubler for cracking, and internal detailed and HFEC inspections of the upper and lower skin panels for cracking (for airplanes with a stringer 6 lap joint modification installed between STA 340 and STA 400 as specified in Boeing Service Bulletin 747-53-2272); or internal detailed and surface HFEC inspections for any crack in the skin or internal doubler (for airplanes with lap joints modified as specified in Boeing Alert Service Bulletin 747-53A2499.)
(3) For airplanes identified as Groups 1, 7, and 12 through 18 in Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014: Internal detailed and surface HFEC inspections for any crack in the skin or internal doubler.
(1) Where Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, specifies a compliance time “after the Revision 3 date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(2) Where Boeing Alert Service Bulletin 747-53A2499, Revision 3, dated July 15, 2014, specifies to contact Boeing for repair instructions: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
