AD 2006-12-12 Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR Series Airplanes

Models named: 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, 747SR series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes, certificated in any category.

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 the Requirements of AD 2001-14-22 Repetitive Inspections (f) For Boeing Model 747-100, 747-100B, 747-100B SUD, -200B, 747-200C, and 747-200F series airplanes, as identified in Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000: Do detailed, surface high-frequency eddy current (HFEC), and open-hole HFEC inspections, as applicable, for cracking of the station 800 frame assembly (including the inner chord strap, angles, and exposed web) between stringers 14 and 18, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000; or Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005; after the effective date of this AD, only Revision 1 of the service bulletin may be used. Except as provided by paragraph (g) of this AD, do the inspection at the applicable time specified in Table 1 of this AD, and repeat the inspections thereafter at intervals not to exceed 3,000 flight cycles until the initial inspections required by paragraph (h) of this AD are accomplished. Table 1.—Compliance Times Total flight cycles as of August 30, 2001 (the effective date of AD 2001-14-22) Do the inspection in paragraph (f) of this AD at this time (1) Fewer than 19,000 Before the accumulation of 19,000 total flight cycles, or within 1,500 flight cycles after August 30, 2001, whichever comes later. (2) 19,000 or more, but 21,250 or fewer Within 1,500 flight cycles or 12 months after August 30, 2001, whichever comes first. (3) 21,251 or more Within 750 flight cycles or 12 months after August 30, 2001, whichever comes first. Adjustments to Compliance Time: Cabin Differential Pressure (g) For Boeing Model 747-100, 747-100B, 747-100B SUD, -200B, 747-200C, and 747-200F series airplanes, as identified in Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000, that are inspected before the effective date of this AD: Except as provided by paragraph (i) of this AD, for the purposes of calculating the compliance threshold and repetitive interval for the actions required by paragraph (f) of this AD, the number of flight cycles in which cabin differential pressure is at 2.0 pounds per square inch (psi) or less need not be counted when determining the number of flight cycles that have occurred on the airplane, provided that the flight cycles with momentary spikes in cabin differential pressure above 2.0 psi are included as full pressure cycles. For this provision to apply, all cabin pressure records must be maintained for each airplane: No fleet-averaging of cabin pressure is allowed. New Requirements of this AD Repetitive Inspections of Expanded Area at a New Reduced Threshold (h) For all airplanes, at the applicable time specified in Table 2 of this AD, except as provided by paragraph (i) of this AD, do the following inspections of the station 800 frame assembly in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005: A detailed inspection for cracking of the inner chord strap, angles, and exposed web adjacent to the inner chords on the station 800 frame between stringer 14 and stringer 18; and surface HFEC and open-hole HFEC inspections for cracking of the inner chord strap and angles. Do the initial inspections at the applicable time specified in Table 2 of this AD, and repeat the inspections thereafter at intervals not to exceed 3,000 flight cycles. Accomplishing the initial inspections required by this paragraph terminates the inspection requirements of paragraph (f) of this AD.  Table 2.—Revised Compliance Times Total flight cycles as of the effective date of this AD Do the inspections in paragraph (h) of this AD at this time (1) Fewer than 16,000 Before the accumulation of 16,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever comes later. (2) 16,000 or more, but 24,250 or fewer Within 1,500 flight cycles after the effective date of this AD. (3) 24,251 or more Within 750 flight cycles after the effective date of this AD. Adjustments to Compliance Time: Cabin Differential Pressure (i) For the purposes of calculating the compliance threshold and repetitive interval for actions required by paragraphs (f) and (h) of this AD, on or after the effective date of this AD: All flight cycles, including the number of flight cycles in which cabin differential pressure is at 2.0 psi or less, must be counted when determining the number of flight cycles that have occurred on the airplane. However, for airplanes on which the repetitive interval for the actions required by paragraph (f) of this AD have been calculated in accordance with paragraph (g) of this AD by excluding the number of flight cycles in which cabin differential pressure is at 2.0 pounds psi or less: Continue to adjust the repetitive inspection interval in accordance with paragraph (g) of this AD until the initial inspections required by paragraph (h) of this AD are accomplished. Thereafter, no adjustment to compliance times based on paragraph (g) of this AD is allowed. Repair (j) If any cracking is detected during any inspection required by paragraph (f) or (h) of this AD, and the service bulletin specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD. No Report Required (k) Although the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000; and Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005; describe procedures for reporting certain information to the manufacturer, this AD does not require that report. 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. (4) AMOCs approved previously in accordance with AD 2001-14-22, are approved as AMOCs for the corresponding provisions of paragraphs (f) and (j) of this AD. Material Incorporated by Reference (m) You must use Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000; or Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005; as applicable; to perform the actions that are required by this AD, unless the AD specifies otherwise. (1) The Director of the Federal Register approved the incorporation by reference of Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. (2) On August 30, 2001 (66 FR 38891, July 26, 2001), the Director of the Federal Register approved the incorporation by reference of Boeing Alert Service Bulletin 747-53A2451, including Appendix A, dated October 5, 2000. (3) 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 May 31, 2006. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 06-5207 Filed 6-9-06; 8:45 am] BILLING CODE 4910-13-P

This AD results from several reports of cracks of the station 800 frame assembly on airplanes that had accumulated fewer total flight cycles than the initial inspection threshold in the existing AD. We are issuing this AD to detect and correct fatigue cracks that could extend and fully sever the frame, which could result in development of skin cracks that could lead to rapid depressurization of the airplane.