Airworthiness Directive · Amendment 39-14806 · Boeing Model 747 Airplanes
Boeing Model 747 Airplanes
This AD applies to Boeing 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; as identified in Boeing Alert Service Bulletin 747-53A2501, dated March 24, 2005.
The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747 airplanes. This AD requires repetitive mid- and low-frequency eddy current inspections for cracks in the overlapped skin panels in the fuselage skin lap joints in sections 41, 42, 44, and 46, and corrective actions if necessary. This AD results from a report indicating that an operator found multiple small cracks in the overlapped skin panels in the fuselage skin lap joints. We are issuing this AD to detect and correct cracks in the overlapped skin panels, which could join together and result in reduced structural capability in the skin and consequent 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 with line numbers 1 through 200 inclusive, at the applicable time in paragraph (f)(1) or (f)(2) of this AD: Do the applicable eddy current inspection or inspections for cracks in the overlapped skin panels in the fuselage skin lap joints in sections 41, 42, 44, and 46; and do all applicable corrective actions before further flight. Except as provided by paragraph (f)(1)(ii) of this AD, repeat the applicable inspection or inspections thereafter at intervals not to exceed 3,000 flight cycles. Except as provided by paragraph (h) of this AD, do all actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2501, dated March 24, 2005.
(1) Except as provided by paragraph (f)(2) of this AD, do the applicable action in paragraph (f)(1)(i) or (f)(1)(ii) of this AD.
(i) For airplanes that have accumulated fewer than 29,000 total flight cycles as of the effective date of this AD: Before the accumulation of 25,000 total flight cycles, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later, do a mid-frequency eddy current inspection for cracks of the internal surface at the overlapped skin around the bottom row of fasteners in the lap joint.
(ii) For airplanes that have accumulated 29,000 or more total flight cycles, do the inspections in accordance with the requirements of AD 2004-13-02, amendment 39-13682, at the applicable threshold and intervals in that AD. Doing the repeat inspections in accordance with AD 2004-13-02, terminates the repetitive inspection requirements of this AD only for airplanes with line numbers 1 through 200 inclusive.
(2) For airplanes that have had overlapped skin panels replaced: Do the eddy current inspections of the replaced overlapped panel prior to the accumulation of 25,000 total flight cycles since panel replacement, or within 1,000 flight cycles after the effective date of this AD, whichever occurs later. Skin panel replacement, along with ongoing inspections in accordance with paragraph (f) of this AD, terminates the requirements of paragraphs (a) and (d) of AD 2004-13-02, only for the skin lap sections where the overlapped panel has been replaced.
For airplanes with line numbers 201 and subsequent: Before the accumulation of 25,000 total flight cycles, within 1,000 flight cycles after the effective date of this AD, or within 25,000 flight cycles after the time when the overlapped skin was replaced, whichever occurs later, do the applicable inspection in paragraphs (g)(1) and (g)(2) of this AD for cracks in the overlapped skin panels in the fuselage skin lap joints in sections 41, 42, 44, and 46; and do all applicable corrective actions before further flight. Repeat the applicable inspection thereafter at intervals not to exceed 3,000 flight cycles. Except as provided by paragraph (h) of this AD, do all actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2501, dated March 24, 2005.
(1) Do a mid-frequency eddy current inspection for cracks of the internal surface at the overlapped skin around the bottom row of fasteners in the lap joint.
(2) Do a low-frequency eddy current inspection for cracks of the overlapped skin around the bottom row of fasteners at the section 41 lap joints with four rows of fasteners.
If any crack is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2501, dated March 24, 2005, 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 (j) of this AD.
(i) Although Boeing Alert Service Bulletin 747-53A2501, dated March 24, 2005, specifies to submit certain information to the manufacturer, this AD does not include that requirement.
