AD 2007-02-24 Airworthiness Directives; Boeing Model 747 Airplanes

Models named: 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F. 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, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP 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. Repetitive Inspections (f) Before the airplane accumulates 28,000 total flight cycles, or within 18 months after the effective date of this AD, whichever occurs later: Do a high-frequency eddy current inspection for cracking of the web of the STA 2360 aft pressure bulkhead around the fastener heads in the critical fastener rows in the web lap joints, from the Y-chord to the inner ring; in accordance with Part 2, “Access and Inspection,” of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005. It is not necessary to inspect the web lap joints in the areas common to the Y-ring outer chord. Repeat the inspection thereafter at intervals not to exceed 2,000 flight cycles until the modification in paragraph (h) of this AD is done. Repair (g) If any cracking is found during any inspection required by paragraph (f) of this AD: Before further flight, do the applicable action in paragraph (g)(1) or (g)(2) of this AD. (1) If the cracking is within certain limits specified in Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005 (referencing the structural repair manual), do the repair in accordance with the Accomplishment Instructions of the alert service bulletin. (2) If the cracking is more than certain limits specified in Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005, or if the alert service bulletin specifies to ask Boeing for repair data: Repair the cracking using a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD. Modification (h) Before the airplane accumulates 35,000 total flight cycles or within 18 months after the effective date of this AD, whichever occurs later: Modify the aft pressure bulkhead using a method approved by the Manager, Seattle ACO. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD. Doing this modification terminates the repetitive inspection requirements of paragraph (f) of this AD. Note 1: As of the effective date of this AD, the manufacturer has not informed us of any intent to produce the required terminating modification; however, the regulations do not prevent others from doing so. Alternative Methods of Compliance (AMOCs) (i)(1) The Manager, Seattle ACO, 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. Material Incorporated by Reference (j) You must use Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005, to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 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 January 19, 2007. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E7-1212 Filed 1-26-07; 8:45 am] BILLING CODE 4910-13-P

This AD results from analysis by the manufacturer that the radial lap splices of the station (STA) 2360 aft pressure bulkhead are subject to widespread fatigue damage. We are issuing this AD to detect and correct cracking of the bulkhead web at multiple sites along the radial lap splice, which could join together to form cracks of critical length, and result in rapid decompression and loss of control of the airplane.