Airworthiness Directive · Amendment 39-16362 · Fuselage
The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP Series Airplanes
This AD applies to The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009.
We are adopting a new airworthiness directive (AD) for certain Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes. This AD requires repetitive detailed inspections of certain overwing intercostal webs, and related investigative and corrective actions if necessary. This AD results from reports of cracks in overwing intercostal webs. We are issuing this AD to detect and correct such cracking, which could grow and result in a severed intercostal. If an intercostal is severed, cracks could develop in the adjacent frame structure and skin, resulting in a rapid loss of cabin pressure.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Before the accumulation of 8,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later: Do a detailed inspection of the left-side and right-side STAs 1160, 1180, 1200, and 1220 overwing intercostal webs, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, except as required by paragraph (i) of this AD. Do all applicable related investigative and corrective actions before further flight. If no cracking is found during any detailed inspection, repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.
(h) For any airplane with an overwing intercostal web replaced in accordance with Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009: Within 6,000 flight cycles after the web was replaced, do a detailed inspection of the replacement overwing intercostal web, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, except as required by paragraph (i) of this AD. Do all applicable related investigative and corrective actions before further flight. If no cracking is found during any detailed inspection, repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.
(i) If any cracking is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, specifies contacting Boeing for appropriate action: Before further flight, repair the cracking using a method approved in accordance with the procedures provided in paragraph (j) of this AD.
