AD 2010-25-06 Airworthiness Directives; The Boeing Company Model 737-200, -300, -400, and -500 Series Airplanes

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

This AD applies to The Boeing Company Model 737-200, -300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009.

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 and Corrective Actions (g) At the applicable time specified in paragraph (g)(1), (g)(2), or (g)(3) of this AD: Do a detailed or high frequency eddy current (HFEC) inspection for cracking of body station (BS) 616 and BS 639 frame webs, inner chord, and outer chord, and the stub beams; and do all applicable related investigative and corrective actions; by accomplishing all the actions specified in Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, except as specified in paragraphs (i) and (j) of this AD. Do all applicable related investigative and corrective actions before further flight. Thereafter, repeat the inspection at intervals not to exceed 4,500 flight cycles since accomplishing the detailed inspection or at intervals not to exceed 9,000 flight cycles since accomplishing the HFEC inspection, as applicable. (1) For airplanes on which no inspection of the BS 616 and BS 639 frames specified in Boeing Alert Service Bulletin 737-53A1254, dated February 17, 2005, has been done as of the effective date of this AD, and that have accumulated fewer than 55,000 total flight cycles as of the effective date of this AD: Inspect within 3,000 flight cycles after the effective date of this AD, or before the accumulation of 56,500 total flight cycles, whichever occurs first. (2) For airplanes on which no inspection of the BS 616 and BS 639 frames specified in Boeing Alert Service Bulletin 737-53A1254, dated February 17, 2005, has been done as of the effective date of this AD, and that have accumulated 55,000 or more total flight cycles as of the effective date of this AD: Inspect within 1,500 flight cycles after the effective date of this AD. (3) For airplanes on which a detailed or HFEC inspection of the BS 616 and BS 639 frames, specified in Boeing Alert Service Bulletin 737-53A1254, dated February 17, 2005, has been done as of the effective date of this AD: Inspect within 4,500 flight cycles after the previous inspection done in accordance with Boeing Alert Service Bulletin 737-53A1254, dated February 17, 2005, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later. Post-Repair Repetitive Inspections and Corrective Actions (h) For airplanes on which the repair specified in Part 4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, has been done: At the applicable time specified in paragraphs (h)(1) and (h)(2) of this AD, do a detailed or HFEC inspection for cracking of the replacement frame section (frame webs, inner chord, and outer chord); and do all applicable related investigative and corrective actions; by accomplishing all the actions specified in Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, except as specified in paragraphs (i) and (j) of this AD. Do all applicable related investigative and corrective actions before further flight. Thereafter, repeat the inspection at intervals not to exceed 4,500 flight cycles since accomplishing the detailed inspection or at intervals not to exceed 9,000 flight cycles since accomplishing the HFEC inspection, as applicable. (1) For airplanes on which a partial frame splice repair at BS 616 or BS 639 has been done, and the inner chord and web have been cold-worked: Inspect within 44,000 flight cycles after the repair has been done. (2) For airplanes on which a partial frame splice repair at BS 616 or BS 639 has been done, and the inner chord and web have not been cold-worked: Inspect within 29,000 flight cycles after that repair has been done. Alternative Inspection of Repaired or Modified Area (i) For airplanes on which a repair or preventative modification exists on the inner chord below the floor which prevents the accomplishment of the detailed or HFEC inspection in that area as required by paragraph (g) of this AD: In lieu of inspecting that area, do a detailed or HFEC inspection of the inner chord along the length of the repair and around the fastener heads in accordance with Part 1 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009. Exceptions to Service Information (j) Where Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, specifies to contact Boeing for repair instructions and repair: Before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (m) of this AD. (k) Although Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, specifies to submit information to the manufacturer, this AD does not include that requirement. Terminating Action (l) Doing the repair specified in Part 4 of Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, terminates the repetitive inspection requirements of paragraph (g) of this AD for the repaired frame only. Alternative Methods of Compliance (AMOCs) (m)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6447; fax (425) 917-6590. Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD. (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 Organization Designation Authorization (ODA) that 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. Material Incorporated by Reference (n) You must use Boeing Alert Service Bulletin 737-53A1254, Revision 1, dated July 9, 2009, to do the actions required by this AD, unless the AD specifies otherwise. (1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51. (2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P. O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; e-mail me.boecom@boeing.com; Internet https://www.myboeingfleet.com. (3) You may review copies of the service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221. (4) You may also review copies of the service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at 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 December 16, 2010. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 2010-32354 Filed 12-27-10; 8:45 am] BILLING CODE 4910-13-P

This AD results from the detection of fatigue cracks at certain frame sections, in addition to stub beam cracking, caused by high flight cycle stresses from both pressurization and maneuver loads. The Federal Aviation Administration is issuing this AD to detect and correct fatigue cracking of certain fuselage frames and stub beams and possible severed frames, which could result in reduced structural integrity of the frames. This reduced structural integrity can increase loading in the fuselage skin, which will accelerate skin crack growth and could result in rapid decompression of the fuselage.