AD 2006-09-01 Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes

Models named: 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, 747SP series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; equipped with Pratt & Whitney JT9D-3 and -7 series engines, except JT9D-70 engines; as identified in Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Restatement of Requirements of AD 2005-19-06 Service Bulletin References (f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005. Repetitive Inspections of Thrust Links (g) Within 90 days after September 30, 2005 (the effective date of AD 2005-19-06), do a detailed inspection and ultrasonic inspection of thrust link lugs having part number (P/N) 65B90360-1 or -4 of the rear engine mount of struts 1, 2, 3, and 4 for any crack or fracture, in accordance with Part 1 of the service bulletin. If the thrust link is not found cracked or fractured: Repeat the inspections thereafter at intervals not to exceed 1,200 flight cycles or 18 months, whichever is first, until the repetitive replacement or overhaul of the thrust link required by paragraph (k) of this AD is accomplished. Accomplishing the repetitive replacement or overhaul of a thrust link as specified in paragraph (h) or (k) of this AD terminates the repetitive inspections for that thrust link only. Corrective Actions (h) If a cracked thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraph (h)(1) of this AD. If a fractured thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraphs (h)(1) and (h)(2) of this AD. (1) Replace the thrust link with a new or overhauled thrust link in accordance with Part 2 of the service bulletin; except as provided by paragraph (i) of this AD. Repeat the replacement at the applicable compliance time specified in paragraph (h)(1)(i) or (h)(1)(ii) of this AD. (i) For replacement with a thrust link assembly having P/N 65B90360-1 or -4: Thereafter at intervals not to exceed 6,000 flight cycles. (ii) For replacement with a thrust link assembly having P/N 65B90360-7: Thereafter at intervals not to exceed 12,000 flight cycles. (2) Do the corrective actions in accordance with Parts 3, 4, and 5 of the service bulletin; except as provided by paragraph (i) of this AD. Exception to Service Bulletin (i) Where the service bulletin specifies to contact Boeing for appropriate action, do the corrective action using a method approved in accordance with paragraph (l) of this AD. Credit for Certain Corrective Actions (j) Reworking the lugs on the bulkhead fitting of the rear engine mount as specified in paragraphs (b)(2), (e), and (f) of AD 2001-15-15, amendment 39-12349, is acceptable for compliance with accomplishing the corrective action specified in “Part 3—Rear Engine Mount Bulkhead Inspection and Lug Overhaul and Upper Fitting Overhaul and Bolt Replacement” of the service bulletin. New Requirements of This AD Terminating Action—Repetitive Replacement or Overhaul of All Thrust Links (k) At the applicable compliance times specified in Table 1 of this AD: Repetitively replace the thrust link of the rear engine mount of struts 1, 2, 3, and 4 with a new or overhauled thrust link, in accordance with Part 2 of the service bulletin; except as provided by paragraph (i) of this AD. During any replacement required by this paragraph, an existing thrust link may be replaced with a new or overhauled thrust link having P/N 65B90360-1, -4 or -7, provided that the applicable repetitive interval specified in Table 1 of this AD is complied with. If a fractured thrust link is found during any replacement or overhaul done in accordance with this paragraph: Before further flight, do the corrective actions specified in paragraph (h)(2) of this AD. Repetitive replacement of all thrust links having P/N 65B90360-1 or -4 terminates the repetitive inspections required by paragraph (g) of this AD. Accomplishing the repetitive replacement or overhaul of a thrust link required by paragraph (h) of this AD constitutes compliance with the requirements of this paragraph for that thrust link only. Table 1.—Compliance Times For thrust link P/N— Initial replacement— Repetitive interval— 65B90360-1 or -4 Within 36 months after the effective date of this AD Thereafter at intervals not to exceed 6,000 flight cycles. 65B90360-7 Within 12,000 flight cycles after the new thrust link has been installed Thereafter at intervals not to exceed 12,000 flight cycles. Alternative Methods of Compliance (AMOCs) (l)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. (3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. (4) The actions identified in paragraphs (g) and (k) of this AD are approved as an AMOC to paragraphs (c) and (d) of AD 2004-07-22, amendment 39-13566, for the inspections of structural significant item S-2, for the thrust links only, of Boeing Supplemental Structural Inspection Document D6-35022, Revision G, dated December 2000. All provisions of AD 2004-07-22 that are not specifically referenced in this paragraph, including the initial inspection threshold required by paragraph (d) of AD 2004-07-22, remain fully applicable and must be complied with. (5) AMOCs approved previously in accordance with AD 2005-19-06, amendment 39-14271, are approved as AMOCs for the corresponding provisions of this AD. Material Incorporated by Reference (m) You must use Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005, to perform the actions that are required by this AD, unless the AD specifies otherwise. On September 30, 2005 (70 FR 54474, September 15, 2005), the Director of the Federal Register approved the incorporation by reference of Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005. Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. Issued in Renton, Washington, on April 13, 2006. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 06-3796 Filed 4-20-06; 8:45 am] BILLING CODE 4910-13-P

This AD results from the finding of fractured and cracked forward lugs of the rear engine mount thrust link on the number one strut on two airplanes. We are issuing this AD to prevent cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control of the airplane.