Airworthiness Directive · Amendment 39-11748 · Boeing Model 747-100, -200, -300, 747SR, and 747SP Series Airplanes
Boeing Model 747-100, -200, -300, 747SR, and 747SP Series Airplanes
Model 747-100, 747-200, 747-300, 747SR, and 747SP series airplanes; having line positions 201 through 886 inclusive; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This document corrects information in an existing airworthiness directive (AD) that applies to certain Boeing Model 747- 100, -200, -300, 747SR, and 747SP series airplanes. That AD currently requires repetitive inspections to detect cracking of the longeron splice fittings at stringer 11, on the left and right sides at body station 2598, and replacement of any cracked fitting with a new fitting. This document clarifies the applicable compliance time for certain airplanes. This correction is necessary to ensure that fatigue cracking on longeron splice fittings, which could result in reduced controllability of the horizontal stabilizer, is detected and corrected in a timely manner.
To detect and correct fatigue cracking of the longeron splice fittings at stringer 11, which could result in reduced controllability of the horizontal stabilizer, accomplish the following:
(a) Perform a one-time detailed visual inspection to detect cracking of the longeron fittings at stringer 11, on the left and right sides at body station 2598, at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2410, Revision 2, dated October 30, 1997, including Addendum; or Boeing Service Bulletin 747-53A2410, Revision 3, dated March 12, 1998, including Addendum. After the effective date of this AD, only Revision 3 shall be used.
(1) For airplanes that have accumulated fewer than 17,000 total flight cycles and 63,000 total flight hours as of the effective date of this AD: Inspect at the later of the times specified in paragraph (a)(1)(i) or (a)(1)(ii) of this AD.
(i) Prior to the accumulation of 17,000 total flight cycles or 63,000 total flight hours, whichever occurs first.
(ii) Within 1,800 flight cycles or 7,000 flight hours after the effective date of this AD, whichever occurs first.
(2) For airplanes that have accumulated 17,000 total flight cycles or more, or 63,000 total flight hours or more, as of the effective date of this AD: Inspect at the earlier of the times specified in paragraphs (a)(2)(i) and (a)(2)(ii) of this AD.
(i) Prior to the accumulation of 22,000 total flight cycles or 78,000 total flight hours, whichever occurs first.
(ii) Within 1,800 flight cycles or 7,000 flight hours after the effective date of this AD, whichever occurs first.
Note 2: Where there are differences between the AD and the service bulletin, the AD prevails.
Note 3: For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
(b) If no crack is found during the inspection required by paragraph (a) of this AD, repeat the inspection one time at the later of the times specified in paragraphs (b)(1) and (b)(2) of this AD, and thereafter at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first.
(1) Within 3,000 flight cycles or 18,000 flight hours after accomplishment of the most recent inspection, whichever occurs first.
(2) Within 1,800 flight cycles or 7,000 flight hours after the effective date of this AD, whichever occurs first.
(c) If any crack is found during any inspection required by paragraph (a) or (b) of this AD: Prior to further flight, replace the cracked fitting with a new fitting, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2410, Revision 2, dated October 30, 1997, including Addendum; or Boeing Service Bulletin 747-53A2410, Revision 3, dated March 12, 1998, including Addendum. After the effective date of this AD, only Revision 3 shall be used. Then, repeat the inspection specified in paragraph (a) of this AD at the later of the times specified in paragraphs (c)(1) and (c)(2) of this AD, and thereafter at intervals not to exceed 3,000 flight cycles or 18,000 flight hours, whichever occurs first.
(1) Within 17,000 flight cycles or 63,000 flight hours after replacement, whichever occurs first.
(2) Within 1,800 flight cycles or 7,000 flight hours after the effective date of this AD, whichever occurs first.
