Airworthiness Directive · Amendment 39-16464 · Fuselage
The Boeing Company Model 747-100, 747-200B, and 747-200F Series Airplanes
This AD applies to The Boeing Company Model 747-100, 747-200B, and 747-200F series airplanes, certificated in any category, as identified in Boeing Service Bulletin 747-53-2307, Revision 3, dated April 16, 2009.
The FAA is superseding two existing airworthiness directives (ADs), which apply to certain Model 747-100, 747-200B, and 747-200F series airplanes. The existing ADs currently require inspections to detect fatigue-related skin cracks and corrosion of the skin panel lap joints in the fuselage upper lobe, and repair if necessary. One of the existing ADs, AD 94-12-09, also requires modification of certain lap joints and inspection of modified lap joints. The other AD, AD 90-15- 06, requires repetitive detailed external visual inspections of the fuselage skin at the upper lobe skin lap joints for cracks and evidence of corrosion, and related investigative and corrective actions. This AD reduces the maximum interval of the post-modification inspections, and adds post-repair inspection requirements for certain airplanes. This AD results from reports of cracking on modified airplanes. We are issuing this AD to detect and correct fatigue cracking and corrosion in the fuselage upper lobe skin lap joints, which could lead to rapid decompression of the airplane and inability of the structure to carry 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.
Within 1,000 flight cycles after July 13, 1994 (the effective date of AD 94-12-09), and thereafter at the intervals specified in paragraphs (g)(1), (g)(2), and (g)(3) of this AD, perform inspections at the upper lobe skin panel lap joints in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(1) Perform a detailed external visual inspection to detect cracks and evidence of corrosion (bulging skin between fasteners, blistered paint, dished fasteners, popped rivet heads, or loose fasteners) in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used. Repeat that inspection thereafter at intervals not to exceed 2,000 flight cycles until the modification required by paragraph (k) of this AD is accomplished.
(2) Perform a high frequency eddy current (HFEC) inspection to detect cracks in the skin at the upper row of fasteners of the skin panel lap joints forward of body station (BS) 1000 in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used. Repeat that inspection thereafter at intervals not to exceed 4,000 flight cycles until the modification required by paragraph (k) of this AD is accomplished.
(3) Perform a HFEC inspection to detect cracks in the skin at the upper row of fastener holes of the skin panel lap joints aft of BS 1480 to 2360 in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
Repeat that inspection thereafter at intervals not to exceed 6,000 flight cycles until the modification required by paragraph (k) of this AD is accomplished.
(h) If any crack is found during any inspection required by paragraph (g) or (l) of this AD, or if any corrosion is found for which material loss exceeds 10 percent of the material thickness, accomplish paragraphs (h)(1) and (h)(2) of this AD in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(1) Prior to further flight, repair any crack or corrosion found, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(2) Within 18 months after accomplishing the repair, accomplish the “full” modification described in Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009; for the remainder of any skin panel lap joint in which a crack is found, or in which corrosion is found that exceeds 10 percent of the material thickness, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(i) If no crack is found during any inspection required by paragraph (g) of this AD, but corrosion is found for which the material loss does not exceed 10 percent of the material thickness: Accomplish the actions specified in paragraphs (i)(1) and (i)(2) of this AD for the entire affected skin panel lap joint, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(1) Within 500 flight cycles after accomplishing the inspection during which the corrosion was found, and thereafter at intervals not to exceed 500 flight cycles until the “full” modification required by paragraph (i)(2) of this AD is accomplished: Perform a HFEC inspection to detect cracks of the corroded skin panel lap joint, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(2) Within 36 months after accomplishing the inspection during which the corrosion was found: Accomplish the “full” modification, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used.
(j) The inspections required by paragraph (g) of this AD shall be performed by removing the paint and using an approved chemical stripper; or by ensuring that each fastener head is clearly visible.
(k) Except as provided in paragraph (m) of this AD, prior to the accumulation of 20,000 total flight cycles, or within the next 1,000 flight cycles after July 13, 1994, whichever occurs later: Accomplish the modification described in Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009; as a “full” modification of the skin panel lap joints at the locations specified in paragraphs (k)(1) and (k)(2) of this AD, as applicable, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. After the effective date of this AD, only Revision 3 may be used. Accomplishment of this modification terminates the repetitive inspection requirements of paragraph (g) of this AD.
(1) For airplane line numbers 001 through 058, inclusive: Modify the skin panel lap joints at Stringer 12 (left and right), station 520 to 1,000; and Stringer 19 (left and right), station 520 to 740.
(2) For airplane line numbers 59 through 200, inclusive: Modify the skin panel lap joints at Stringer 12 (left and right), station 740 to 1,000; and Stringer 19 (left and right), station 520 to 740.
(l) For all airplanes: Perform an external HFEC inspection to detect skin cracks of any modified skin panel lap joints at the times specified in paragraphs (l)(1), (l)(2), and (l)(3) of this AD, as applicable, in accordance with Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009. As of the effective date of this AD, only Revision 3 may be used. Repeat that inspection thereafter at intervals not to exceed 3,000 flight cycles, except as required by paragraph (n) of this AD.
(1) For skin panel lap joints on which the “full” modification has been accomplished: Within 10,000 flight cycles after accomplishment of that modification.
(2) For skin panel lap joints on which the “optional” (partial) modification has been accomplished: Within 7,000 flight cycles after accomplishment of that modification.
(3) For skin panel lap joints having deep countersink fasteners located at Section 42 on which the “full” modification, as described in Boeing Service Bulletin 747-53-2307, dated December 21, 1989, has been accomplished: Within 5,000 flight cycles after accomplishment of that modification.
(m) In lieu of the “full” modification required by paragraph (k) of this AD, the “optional” (partial) modification described in Boeing Service Bulletin 747-53-2307, Revision 2, dated October 14, 1993; or Revision 3, dated April 16, 2009; may be accomplished for skin panels that have an outer thickness of 0.090 inches or less, and that do not have any cracks, corrosion, or an existing structural repair on the skin panel lap joint. After the effective date of this AD, only Revision 3 may be used. The “optional” (partial) modification shall not be accomplished at deep countersink fastener locations. Accomplishment of this modification terminates the repetitive inspection requirements of paragraph (g) of this AD.
Repeat the inspection required by paragraph (l) of this AD at the earlier of the times specified in paragraphs (n)(1) and (n)(2) of this AD. Thereafter, repeat the inspection at intervals not to exceed 1,000 flight cycles.
(1) Within 3,000 flight cycles after the last inspection done in accordance with paragraph (l) of this AD.
(2) Within 1,000 flight cycles after the last inspection done in accordance with paragraph (l) of this AD or 500 flight cycles after the effective date of this AD, whichever occurs later.
For all airplanes: Do an internal surface HFEC inspection for cracking of the skin at any external doubler repairs greater than 40 inches in length (in the horizontal direction) within 1,000 flight cycles after the effective date of this AD, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-53-2307, Revision 3, dated April 16, 2009. Thereafter, perform that inspection at intervals not to exceed 3,000 flight cycles.
(p) If any cracking is found during any inspection required by paragraph (o) of this AD, repair in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-53-2307, Revision 3, dated April 16, 2009.
