Airworthiness Directive · Amendment 39-12047 · Boeing Model 747 Series Airplanes
Boeing Model 747 Series Airplanes
Superseded. A later AD replaced this one: AD 2003-16-12. Comply with the one in force.
Model 747 series airplanes, as listed in Boeing Alert Service Bulletin 747-57A2311, dated January 27, 2000; 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 amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that requires inspections to detect cracking of the front spar web of the wing, and corrective action, if necessary. The actions specified by this AD are necessary to detect and correct fatigue cracking of the front spar web, which could result in fuel leaking onto an engine and a consequent fire. This action is intended to address the identified unsafe condition.
To detect and correct fatigue cracking of the front spar web of the wing, which could result in fuel leaking onto an engine and a consequent fire, accomplish the following:
(a) At the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD, except as provided by paragraph (b) of this AD, perform the Part 1 external web inspection—including detailed visual, ultrasonic, and high frequency eddy current (HFEC) inspections—to detect cracking of the front spar web of the wing, in accordance with Boeing Alert Service Bulletin 747-57A2311, dated January 27, 2000. In lieu of the Part 1 external web inspection, accomplishment of the Part 2 optional web inspection to detect cracking—which also includes detailed visual, ultrasonic, and HFEC inspections—in accordance with Boeing Alert Service Bulletin 747-57A2311, dated January 27, 2000, is acceptable for compliance with this paragraph. Repeat the inspections thereafter at intervals not to exceed 2,000 flight cycles.
Note 2: 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.”
(1) Prior to the accumulation of 13,000 total flight cycles or 30,000 total flight hours, whichever occurs first.
(2) Within 18 months after the effective date of this AD.
Note 3: Operators of airplanes modified by Boeing Service Bulletin 747-57A2303, Revision 1, dated September 25, 1997; as allowed by paragraph (c) of AD 99-10-09, amendment 39-11162; must apply for an alternative method of compliance, in accordance with paragraph (d) of this AD, if they choose to use the Part 2 optional web inspection to comply with paragraph (a) of this AD.
(b) For airplanes on which the front spar web between front spar station inboard (FSSI) 668 and FSSI 692 has been replaced with a shot-peened front spar web in accordance with AD 99-10-09, amendment 39-11162: Within 13,000 flight cycles or 30,000 flight hours after the replacement, whichever occurs first, inspect the new section of the front spar web that overlaps with the inspection area specified in Boeing Alert Service Bulletin 747-57A2311 (the area between front spar station inboard (FSSI) 668 and FSSI 684), dated January 27, 2000, and repeat the inspections thereafter, in accordance with paragraph (a) of this AD.
(c) If any cracking is detected during any inspection required by paragraph (a) or (b) of this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.
