AD 2009-09-06 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 Alert Service Bulletin 737-53A1269, dated May 17, 2007.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Inspections (f) At the applicable compliance times and repeat intervals listed in the tables of paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1269, dated May 17, 2007 (hereafter “the service bulletin”), except as provided by paragraphs (f)(1), (f)(2), and (f)(3) of this AD: Do repetitive detailed and high frequency eddy current inspections to detect cracks of the backup intercostals and the upper sill of the forward airstair doorway, and applicable corrective actions by accomplishing all the applicable actions specified in the Accomplishment Instructions of the service bulletin. Do the applicable corrective actions before further flight. (1) Where the service bulletin specifies a compliance time from the release date of the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD. (2) Where the columns identified as “Airplane Flight Cycles” in the tables of the service bulletin specify less than 45,000 total flight cycles for certain actions, this AD affects airplanes having less than or equal to 45,000 total flight cycles. (3) Where the columns identified as “Repeat Interval” in the tables of the service bulletin specify an interval of 4,500 flight cycles for all conditions, this AD requires repetitive inspections only if no crack is found during any inspection required by paragraph (f) of this AD. Optional Terminating Action (g) Accomplishing the backup intercostal repair/preventative modification and/or the upper door sill web repair, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1269, dated May 17, 2007, terminates all the corresponding repetitive inspection requirements of paragraph (f) of this AD. Alternative Methods of Compliance (AMOCs) (h)(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: Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (917) 917-6450; fax (425) 917-6590. (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 Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, FAA, 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. Material Incorporated by Reference (i) You must use Boeing Alert Service Bulletin 737-53A1269, dated May 17, 2007, to do the actions required by this AD, unless the AD specifies otherwise. The optional actions specified by this AD, if accomplished, must also be done in accordance with Boeing Alert Service Bulletin 737-53A1269, dated May 17, 2007. (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 or 425-227-1152. (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 April 22, 2009. Stephen P. Boyd, Assistant Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E9-9947 Filed 5-6-09; 8:45 am] BILLING CODE 4910-13-P

This AD results from a report indicating that cracks were found in the backup intercostals and upper sill web of the forward airstair doorway. We are issuing this AD to detect and correct fatigue cracking of the backup intercostals and upper sill web of the forward airstair doorway, which could result in a rapid loss of cabin pressure.