AD 2007-03-03 Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

Models named: 737-100, -200, -200C, -300, -400, -500 series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 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. Repetitive Inspections (f) At the applicable times specified in Table 1 of this AD, do a high frequency eddy current (HFEC) inspection and detailed inspection to detect cracks in the BS 178 vertical beam webs, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005. Table 1.—Compliance Times For airplanes on which— Inspect— And repeat the HFEC and detailed inspections thereafter at— (1) An HFEC or a detailed inspection specified in Boeing Service Bulletin 737-53A1225, dated October 19, 2000, has not been done as of the effective date of this AD Before the accumulation of 15,000 total flight cycles, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later Intervals not to exceed 6,000 flight cycles. (2) An HFEC or detailed inspection specified in Boeing Service Bulletin 737-53A1225, dated October 19, 2000, has been done before the effective date of this AD Within 6,000 flight cycles since the last HFEC inspection, within 1,200 flight cycles since the last detailed inspection, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later Intervals not to exceed 6,000 flight cycles. Corrective Actions (g) If any crack is detected during any inspection required by paragraph (f) of this AD, before further flight, repair or replace the vertical beam web and associated parts with a new vertical beam web, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005, except as provided by paragraph (h) of this AD. (h) If any damage is beyond the scope of the service bulletin or structural repair manual, before further flight, repair the damaged vertical beam web in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or using a method approved in accordance with paragraph (m) of this AD. Terminating Preventative Modification (i) Before the accumulation of 50,000 total flight cycles, or within 25,000 flight cycles after the effective date of this AD, whichever occurs later, replace the vertical beams at buttock lines (BL) 5.7 and 17.0 of the BS 178 bulkhead, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005. Accomplishing the replacement ends the repetitive inspections required by paragraph (f) of this AD. (j) Actions done before the effective date of this AD in accordance with Boeing BOECOM M-7200-01-00546, dated March 1, 2001, are acceptable for compliance with the requirements of paragraph (i) of this AD. Prior to or Concurrent Requirements (k) For Group 1 airplanes identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005: Before or concurrently with the requirements of paragraph (i) of this AD, do the preventative modifications of the center web, vertical chords, and side chord areas, including the side chord areas at water line 207, of the forward pressure bulkhead, specified in paragraph (c) of AD 2000-05-29, amendment 39-11639 (reference Boeing Alert Service Bulletin 737-53A1173, Revision 3, dated May 6, 1999). (l) For Group 2 airplanes identified in Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 2005: Before or concurrently with the requirements of paragraph (i) of this AD, but no later than the time specified in AD 2001-02-01, amendment 39-12085, do the preventative modifications of the vertical and side chord areas of the forward pressure bulkhead required by paragraph (c) of AD 2001-02-01 (reference Boeing Alert Service Bulletin 737-53A1208, dated May 6, 1999). Alternative Methods of Compliance (AMOCs) (m)(1) The Manager, Seattle 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 replacement or 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 replacement or repair method to be approved, the replacement or repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. (4) Approved AMOCs to paragraph (c) of AD 2000-05-29 done before or concurrently with the requirements of paragraph (i) of this AD are approved as AMOCs for the corresponding provisions of paragraph (k) of this AD. (5) Approved AMOCs to paragraph (c) of AD 2001-02-01 done before or concurrently with the requirements of paragraph (i) of this AD are approved as AMOCs for the corresponding provisions of paragraph (l) of this AD. Material Incorporated by Reference (n) You must use Boeing Service Bulletin 737-53A1225, Revision 1, dated April 14, 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. E7-1396 Filed 1-30-07; 8:45 am] BILLING CODE 4910-13-P

This AD results from reports of numerous cracks in the vertical beam webs. We are issuing this AD to prevent fatigue cracks in certain vertical beam webs, which could result in loss of structural integrity of the body station (BS) 178 bulkhead, and consequently could impair the operation of the control cables for the elevators, speed brakes, and landing gear, or could cause the loss of cabin pressure.