Airworthiness Directive · Amendment 39-17052 · Fuselage
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category, as identified in Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009.
We are superseding an existing airworthiness directive (AD) for certain The Boeing Company Model 747 series airplanes. That AD currently requires repetitive inspections for cracks of the fuselage skin lap splice between body station (BS) 400 and BS 520 at stringers S-6L and S-6R, and repair if necessary. This new AD shortens the interval for the repetitive inspections, requires modification for certain airplanes, and requires certain post-modification inspections for other airplanes. This AD was prompted by reports of multiple adjacent cracks on an airplane, and a recent fleet-wide evaluation of widespread fatigue damage of skin lap joints, which indicated the need for revised procedures and reduced compliance times. We are issuing this AD to detect and correct cracking of the fuselage skin lap splice between BS 400 and BS 520 at stringers S-6L and S-6R, which could result in sudden loss of cabin pressurization and the inability of the fuselage to withstand fail-safe loads.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
This paragraph restates the requirements of paragraph A. of AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990), with revised service information, reduced inspection interval, and added subparagraph. Conduct a close visual or detailed inspection, and a high frequency eddy current (HFEC) inspection, of the fuselage skin lap splice between BS 400 and BS 520, at stringers S-6L and S-6R, for cracking, in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; at the times specified in paragraph (g)(1), (g)(2), or (g)(3) of this AD. After the effective date of this AD, only Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, may be used. Adequate lighting must be used for this inspection. The eddy current inspections may be conducted without removal of the paint, provided the paint does not interfere with the inspections. Paint must be removed, using an approved chemical stripper, in any situation where the inspector determines that the paint is interfering with the proper functioning of the inspection instrument.
(1) Within the next 100 landings after March 31, 1989 (the effective date of AD 89-05-03, Amendment 39-6146 (54 FR 7397, February 21, 1989), which was superseded by AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990)), for airplanes that have accumulated 16,000 or more landings as of March 31, 1989, unless previously accomplished within the last 4,900 landings.
(2) Within the next 1,000 landings after March 31, 1989, or prior to the accumulation of 16,000 landings, whichever occurs first, for airplanes that have accumulated between 12,000 and 16,000 landings, as of March 31, 1989 (the effective date of AD 89-05-03, Amendment 39-6146 (54 FR 7397, February 21, 1989), which was superseded by AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990)), unless previously accomplished within the last 4,000 landings.
(3) Prior to the accumulation of 13,000 landings for airplanes that have accumulated 12,000 or fewer landings as of March 31, 1989 (the effective date of AD 89-05-03, Amendment 39-6146 (54 FR 7397, February 21, 1989), which was superseded by AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990)), unless previously accomplished within the last 5,000 landings.
(4) For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
This paragraph restates the requirements of paragraph B. of AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990), with revised service information. On airplanes which have been modified to the stretched-upper-deck configuration, as identified in Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; the accumulated landing threshold for compliance with paragraph (g) of this AD is measured from the time of the stretched-upper-deck modification.
This paragraph restates the requirements of paragraph C. of AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990), with revised service information. If no cracking is detected during the inspections required by paragraph (g) of this AD, repeat the inspections required by paragraph (g) of this AD one time at the earlier of the times specified in paragraphs (i)(1) and (i)(2) of this AD. Thereafter repeat the inspections at intervals not to exceed 3,000 landings.
(1) Within 5,000 landings after the last inspection.
(2) Within 3,000 landings after the last inspection, or within 1,000 landings after the effective date of this AD, whichever occurs later.
This paragraph restates the requirements of paragraph D. of AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990), with revised service information. If cracks are detected during the inspections required by paragraph (g) of this AD, accomplish the repair or preventive modification of the affected lap splice, in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; prior to further pressurized flight. After the effective date of this AD, only Boeing Service Bulletin747-53A2303, Revision 2, dated October 1, 2009, may be used. If cracks are repaired in local areas without accomplishing preventive modification of the entire affected lap area, continue inspections of the unmodified and unrepaired areas of the affected lap splice in accordance with paragraph (i) of this AD.
This paragraph restates the requirements of paragraph E. of AD 90-21-17, Amendment 39-6768 (55 FR 41510, October 12, 1990), with revised service information. For airplanes incorporating the preventive modification, as described in Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, or Revision 1, dated March 29, 1990; or Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009; accomplish the inspections required by paragraph (g) of this AD prior to the accumulation of 10,000 landings after the modification and thereafter at intervals not to exceed 5,000 landings. If cracks are found, repair using a method approved in accordance with the procedures specified in paragraph (q) of this AD, prior to further pressurized flight.
For airplanes on which a protruding head fastener modification has been done in accordance with Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, or Revision 1, dated March 29, 1990: Within 10,000 flight cycles after modification, or within 500 flight cycles after the effective date of this AD, whichever occurs later, do an external HFEC inspection for cracking in the skin around the fasteners in the upper row of the lap joint, in accordance with Part 5 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009. If any crack is found, before further flight repair in accordance with Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009 (except as required by paragraph (p) of this AD), or do the modification specified in paragraph (n) of this AD. Repeat the inspection in affected uncracked areas at intervals not to exceed 500 flight cycles, until the modification specified in paragraph (n) of this AD is done. Accomplishment of the initial inspection and all applicable corrective actions specified in this paragraph terminates the requirements of paragraph (k) of this AD.
For airplanes on which an external doubler repair has been installed as a modification that was done using a method other than that specified in Boeing 747 structural repair manual (SRM) 53-30-03, Figure 19, 25, 28 or 34: Within 10,000 flight cycles after modification, or within 500 flight cycles after the effective date of this AD, whichever occurs later, do an internal HFEC inspection for cracking in the skin around the fasteners in the upper row of the lap joint, in accordance with Part 5 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009. If any crack is found, before further flight repair in accordance with Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009 (except as required by paragraph (p) of this AD), or do the modification specified in paragraph (n) of this AD. Repeat the inspection in affected uncracked areas at intervals not to exceed 500 flight cycles, until the modification specified in paragraph (n) of this AD is done. Accomplishment of the initial inspection and all applicable corrective actions specified in this paragraph terminates the requirements of paragraph (k) of this AD.
For airplanes on which a protruding head fastener modification or a Boeing 747 SRM 53-30-03 repair or modification has been installed that was not done using Boeing 747 SRM 53-30-03, Figure 19, 25, 28, or 34, for the full length of the lap splice: Within 14,000 flight cycles after the first repair or modification was done, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later, modify the skin and do all post-modification inspections and repairs, in accordance with Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, except as required by paragraph (o) of this AD. Do the post-modification inspection within 10,000 flight cycles after installation of the modification. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles. All applicable repairs must be done before further flight.
The provisions of paragraphs (o)(1) and (o)(2) of this AD apply to airplanes on which no previous modification or repair has been installed in the affected area.
(1) Accomplishment of the structural modification specified in Part 3 of the Accomplishment Instructions of Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, satisfies the requirements of AD 90-06-06, Amendment 39-6490 (55 FR 8374, March 7, 1990), for only the corresponding modification specified in Boeing Alert Service Bulletin 747-53A2303, dated June 2, 1988, and Revision 1, dated March 29, 1990; and Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009.
(2) After accomplishment of the modification specified in paragraph (o)(1) of this AD, the applicable requirements and compliance times of paragraphs (l) and (m) of this AD apply.
Where Boeing Service Bulletin 747-53A2303, Revision 2, dated October 1, 2009, specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (q) of this AD.
