Airworthiness Directive · Amendment 39-18448 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SR, and 747SP series airplanes; certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2852, dated June 22, 2012.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-300, 747SR, and 747SP series airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the upper chords of the upper deck floor beams are subject to widespread fatigue damage (WFD). This AD requires repetitive inspections for cracks at the floor panel attachment fastener holes; repetitive inspections for cracks in the upper and lower chords of the upper deck floor beams at permanent fastener locations; repetitive inspections for cracks in certain repaired and modified areas; and related investigative and corrective actions if necessary. This AD also requires repetitive replacement of the upper chords of the upper deck floor beams, including pre-replacement inspections and corrective action if necessary; and post-replacement repetitive inspections and repair if necessary. We are issuing this AD to detect and correct fatigue cracking of the upper chords of the upper deck floor beams. Undetected cracking could result in large deflection or deformation of the upper deck floor beams, resulting in damage to wire bundles and control cables for the flight control system, and reduced controllability of the airplane. Multiple adjacent severed floor beams could result in rapid decompression of the airplane.
At the applicable times specified in Tables 1 through 7 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012, except as required by paragraph (l)(1) of this AD: Do the inspections specified in paragraphs (g)(1) and (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 747-53A2452, Revision 1, dated July 16, 2012, except as required by paragraph (l)(2) of this AD. Repeat the inspections specified in paragraphs (g)(1) and (g)(2) of this AD thereafter at the applicable times specified in Tables 1 through 7 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012. Do all applicable related investigative and corrective actions before further flight. Doing the inspections required by paragraphs (g)(1) and (g)(2) of this AD terminates the inspections required by paragraphs (m) and (n) of AD 2005-20-29, Amendment 39-14326 (70 FR 59246, October 12, 2005).
(1) Do an open hole or surface high frequency eddy current (HFEC) inspection, as applicable, for cracks at the fastener holes of the floor panel attachment in the applicable areas and stations identified in Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012.
(2) Do a surface HFEC inspection for cracks in the upper and lower chords of the upper deck floor beams at permanent fastener locations in the applicable areas and stations identified in Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012.
A fastener hole modification or a fastener hole repair in Area 1 or Area 2 as described in Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012, terminates the inspection of the fastener holes of the floor panel attachment required by paragraph (g)(1) of this AD for the repaired or modified area only, provided the modification and repair, including related investigative and corrective actions, are done in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012, except as required by paragraph (l)(2) of this AD.
(1) For airplanes on which any fastener hole modification or any fastener hole repair was done as specified in Boeing Alert Service Bulletin 747-53A2452: Except as required by paragraph (i)(2) of this AD, at the applicable times specified in Tables 8 and 9 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, do an open hole or surface HFEC inspection, as applicable, for cracks in the repaired and modified areas, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012. If any cracking is found, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (o) of this AD. Repeat the applicable inspections thereafter at the times specified in Tables 8 and 9 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012. Doing an inspection required by this paragraph terminates the inspections required by paragraph (p) of AD 2005-20-29, Amendment 39-14326 (70 FR 59246, October 12, 2005).
(2) For any repair #10 or repair #13 done as specified in Boeing Alert Service Bulletin 747-53A2452: Before further flight, do post-repair inspections using a method approved in accordance with the procedures specified in paragraph (o) of this AD.
Replace the upper chords of the upper deck floor beams by doing the actions required by paragraphs (j)(1) and (j)(2) of this AD at the times specified in those paragraphs. Accomplishing the replacement required by this paragraph terminates the inspections required by paragraphs (g) and (i) of this AD.
(1) Before the accumulation of 30,000 total flight cycles, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later, do an open hole HFEC inspection for cracks at certain fastener locations in the floor beam webs and side of body frames, and do a detailed inspection for cracks of any removed part that will be re-installed, and do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2852, dated June 22, 2012, except as required by paragraph (l)(2) of this AD. Do all applicable corrective actions before further flight.
(2) Before further flight after accomplishing the inspections required by paragraph (j)(1) of this AD, install new upper chords of the upper deck floor beams and reinforcing straps or angles, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2852, dated June 22, 2012, except as required by paragraph (l)(2) of this AD.
For airplanes on which any replacement required by paragraph (j) or (k)(2)(ii) of this AD is done: At the applicable times specified in Tables 2 through 4 in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2852, dated June 22, 2012, do HFEC inspections for cracks at the permanent fastener holes and the upper chords of the upper deck floor beams, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012.
(1) If any cracking is found during any inspection required by the introductory text of paragraph (k) or paragraph (k)(2)(i) of this AD, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (o) of this AD.
(2) If no cracking is found during any inspection required by the introductory text of paragraph (k) or paragraph (k)(2)(i) of this AD, do the actions required by paragraphs (k)(2)(i) and (k)(2)(ii) of this AD.
(i) Repeat the inspections specified in paragraph (k) of this AD thereafter at the applicable times specified in Tables 8 and 9 of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012.
(ii) Within 10,000 flight cycles after accomplishing the initial HFEC inspections required by the introductory text of paragraph (k) of this AD, replace the upper chords of the upper deck floor beams by doing the actions specified in paragraphs (j)(1) and (j)(2) of this AD.
(1) Where Boeing Alert Service Bulletin 747-53A2452, Revision 1, dated July 16, 2012, specifies a compliance time “after the Revision 1 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 747-53A2452, Revision 1, dated July 16, 2012; or Boeing Alert Service Bulletin 747-53A2852, dated June 22, 2012; specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (o) of this AD.
