AD 2008-12-04 Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

Models named: 737-600, -700, -700C, -800, -900 series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category; as identified in Boeing Special Attention Service Bulletin 737-53-1232, dated April 2, 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. Service Bulletin (f) The term “service bulletin,” as used in this AD, means Boeing Special Attention Service Bulletin 737-53-1232, dated April 2, 2007. Inspections and Replacement, As Applicable (g) At the applicable compliance times listed in Tables 1, 2, and 3 of paragraph 1.E., “Compliance,” of the service bulletin, or within the time specified in paragraph (g)(1) or (g)(2) of this AD, as applicable, whichever occurs later, and thereafter at the applicable repeat intervals listed in Tables 1, 2, and 3: Do the applicable inspections and replacement by accomplishing all the applicable actions specified in the Accomplishment Instructions of the service bulletin. (1) For airplanes specified in Tables 1 and 2 of paragraph 1.E., “Compliance,” of the service bulletin: Do the applicable initial inspection required by paragraph (g) of this AD within 36 months after the effective date of this AD. (2) For airplanes specified in Table 3 of paragraph 1.E., “Compliance,” of the service bulletin: Do the applicable initial inspection and replacement required by paragraph (g) of this AD within 24 months after the effective date of this AD. Corrective Actions (h) If any crack or loose or missing fastener is found during any applicable inspection required by paragraph (g) of this AD, before further flight, do the applicable corrective action in accordance with the service bulletin; except, where the service bulletin specifies to contact Boeing for appropriate action, before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (l) of this AD. Terminating Action for Certain Repetitive Inspections (i) For airplanes on which the preventative modification specified in the service bulletin has not been installed: Accomplishing the preventative modification, time-limited repair, or permanent repair in accordance with the service bulletin ends the applicable repetitive external detailed inspections required by paragraph (g) of this AD. Exceptions to the Service Bulletin Procedures for Previously Installed Repairs (j) For any airplane subject to the requirements of paragraph (g) of this AD: Inspections done at the compliance times specified in Table 1 of paragraph 1.E., “Compliance,” of the service bulletin are not required in areas that are spanned by an FAA-approved repair that has a minimum of 3 rows of fasteners above and below the chemically milled step. Post-repair supplemental inspections are to be done at the times specified in Table 2 of paragraph 1.E., “Compliance,” of the service bulletin. (k) For any airplane that has an external doubler covering the chemically milled step, but the doubler does not span the step by a minimum of 3 rows of fasteners above and below the chemically milled step: Instead of requesting approval for an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (l) of this AD, one method of compliance with the inspection requirement of paragraph (g) of this AD is to inspect all chemically milled steps covered by the repair using non-destructive test (NDT) methods in accordance with the Boeing 737 NDT Manual, Part 6, Subject 53-30-20. These repairs are to be considered time-limited and are subject to the post-repair supplemental inspections and replacement at the times specified in Table 3 of paragraph 1.E., “Compliance,” of the service bulletin. 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) 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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. (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, and the approval must specifically refer to this AD. (4) Use of Boeing Model 737 NDT Manual, Part 6, Subject 53-30-25, is an AMOC for Boeing Model 737 NDT Manual, Part 6, Subjects 53-30-19 and 53-30-23, as specified in the service bulletin. Material Incorporated by Reference (m) You must use Boeing Special Attention Service Bulletin 737-53-1232, dated April 2, 2007, 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, P.O. Box 3707, Seattle, Washington 98124-2207. (3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or 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 May 29, 2008. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E8-12761 Filed 6-10-08; 8:45 am] BILLING CODE 4910-13-P

This AD results from a fatigue test that revealed numerous cracks in the upper skin panel at the chemically milled step above the lap joint. We are issuing this AD to detect and correct such fatigue-related cracks, which could result in the crack tips continuing to turn and grow to the point where the skin bay flaps open, causing decompression of the airplane.