Airworthiness Directive · Amendment 39-16546 · Fuselage
The Boeing Company Model 747 Airplanes
This AD applies to all The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires repetitive inspections for cracking in the body skin around the aft corners of the nose wheel well; for certain airplanes, repetitive inspections for cracking in the skin splice plate at the aft corners of the nose wheel well; and related investigative and corrective actions if necessary. This AD also requires repetitive post-modification inspections for cracking in the body skin and the skin splice plate; for certain airplanes, an inspection for steel cross-shaped doublers on the larger aluminum doublers; and corrective action if necessary. This AD also requires repetitive surface high frequency eddy current (HFEC) inspections of a certain bulkhead outer chord, skin splice plate, and outer chord radius filler for cracking; repetitive detailed inspections for cracking of the bulkhead frame web and body skin; and corrective actions if necessary. This AD provides for optional terminating action for certain repetitive inspections. This AD was prompted by reports of cracking of the fuselage skin and adjacent internal skin splice plate at the left and right nose wheel well aft corners, and the outer chord of the body station (BS) 400 bulkhead. We are issuing this AD to detect and correct cracking of the fuselage skin or splice plate, which, together with cracking of the bulkhead outer chord, could result in large skin cracks and subsequent in-flight rapid decompression of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
For airplanes in Groups 1 through 3, as identified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, that have not been modified in accordance with Boeing Service Bulletin 747-53-2150; have not been repaired in accordance with Figure 35 of Section 53-30-03 of Boeing 747 Structural Repair Manual (SRM); and have not been modified in accordance with Boeing Alert Service Bulletin 747-53A2305: Before the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, and skin splice plate at the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(h) For airplanes in Groups 1 through 3, as identified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, that have been modified in accordance with Boeing Service Bulletin 747-53-2150; or repaired in accordance with Figure 35 of Section 53-30-03 of Boeing 747 SRM: Within 6,000 flight cycles after doing the modification or repair, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, and skin splice plate at the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(i) For airplanes in Groups 4 through 7, as identified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, that have not been modified in accordance with Boeing Alert Service Bulletin 747-53A2305: Prior to the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(j) For airplanes in Groups 4 through 7, as identified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, that have been modified in accordance with Boeing Service Bulletin 747-53-2305, dated June 27, 1991; or Revision 1, dated May 22, 1997: Within 1,000 flight cycles after the effective date of this AD, do a one-time external general visual inspection for steel cross-shaped doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009. If no cross-shaped doublers are installed, within 1,500 flight cycles after the effective date of this AD, install cross-shaped doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(k) For airplanes in Group 8, as identified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009: Prior to the accumulation of 3,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later, do an external detailed inspection for cracks in the body skin around the aft corners of the nose wheel well, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(l) If no crack is found during any inspection required by paragraph (g), (h), (i), or (k) of this AD, repeat the applicable inspection specified in paragraph (g), (h), (i), or (k) of this AD thereafter at intervals not to exceed 1,500 flight cycles, until the modification specified in paragraph (n) of this AD is accomplished.
(m) If any crack is found during any inspection required by paragraph (g), (h), (i), (k), or (l) of this AD, before further flight, modify the aft corners of the nose wheel well by installing modification doublers and doing all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, except as required by paragraph (t) of this AD.
Modification of the aft corners of the nose wheel well by installing modification doublers and doing all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, terminates the repetitive inspections required by paragraph (l) of this AD for the modified side only. Where Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, specifies to contact Boeing for appropriate action, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD.
For airplanes on which the modification specified in Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, has been done: At the applicable time specified in paragraph (o)(1) or (o)(2) of this AD, do an external low frequency eddy current inspection for skin cracks around the fasteners at the periphery of the modification doublers, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009.
(1) For airplanes on which the edge row fastener holes common to the external modification doublers have been zero-timed in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009: Within 15,000 flight cycles after accomplishing the modification, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
(2) For airplanes on which the edge row fastener holes common to the external modification doublers have not been zero-timed in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009: Prior to the accumulation of 15,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.
(p) If no cracking is found during the inspection required by paragraph (o) of this AD, repeat the inspection specified in paragraph (o) of this AD thereafter at intervals not to exceed 1,500 flight cycles.
(q) If any cracking is found during any inspection required by paragraph (o) or (p) of this AD, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (u) of this AD.
For all airplanes: At the latest of the times specified in paragraphs (r)(1), (r)(2), and (r)(3) of this AD, do a surface HFEC inspection for cracking in the BS 400 bulkhead outer chord, skin splice plate, and outer chord radius filler; and a detailed inspection for cracking of the bulkhead frame web and body skin; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009. If no cracking is found during any inspection, repeat the inspection one time within 6,000 flight cycles, and thereafter at intervals not to exceed 3,000 flight cycles.
(1) Before the accumulation of 20,000 total flight cycles.
(2) Within 3,000 flight cycles after doing the HFEC inspection required by AD 2004-07-22 R1, Amendment 39-15326, for structural significant item (SSI) F-4B of the Boeing Document No. D6-35022, “Supplemental Structural Inspection Document (SSID) for Model 747 Airplanes,” Revision G, dated December 2000.
(3) Within 1,500 flight cycles after the effective date of this AD.
(s) If any cracking is found during any inspection required by paragraph (r) of this AD, before further flight, repair in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, except as required by paragraph (t) of this AD. Within 6,000 flight cycles after doing the repair, do the inspections specified in paragraph (r) of this AD, and repeat the inspections thereafter at intervals not to exceed 3,000 flight cycles.
If any cracking is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2305, Revision 2, dated January 15, 2009, specifies to contact Boeing for appropriate action: Before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (u) of this AD.
