AD 2011-04-10 Airworthiness Directives; The Boeing Company Model 737-300, -400, and -500 Series Airplanes

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

This AD applies to all The Boeing Company Model 737-300, -400, and -500 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. Restatement of Requirements of AD 2008-15-05, Amendment 39-15617 Inspection To Determine Affected Carriage Spindle (g) For all airplanes: Within 30 days after August 5, 2008 (the effective date of AD 2008-15-05), inspect the carriage sub-assembly to determine whether an affected carriage spindle with a high velocity oxy-fuel (HVOF) thermal coating is installed, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number and/or serial number of the carriage can be conclusively determined from that review. If no affected carriage spindle is installed, no further action is required by this paragraph. Repetitive Inspections, Related Investigative Actions, and Corrective Action (h) For airplanes on which any affected carriage spindle was determined to be installed in accordance with Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008, as of August 5, 2008; and the spindle is identified in Table 2 of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009: At the later of the times specified in paragraphs (h)(1) and (h)(2) of this AD, do a detailed inspection (or, as an option for the forward end of the spindle only, a borescope inspection technique may be used) of the spindle for corrosion and potential indications of corrosion of the carriage spindle, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008; or Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. Do all applicable related investigative and corrective actions before further flight. Repeat the detailed inspection (or, as an option for the forward end of the spindle only, the borescope inspection) and certain related investigative actions (i.e., the gap-check or optional non-destructive test (NDT) ultrasonic inspection) at the applicable compliance times specified in paragraph 1.E. of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008; or Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. (1) Within 30 days after August 5, 2008. (2) Within 90 days after the installation of a new HVOF-coated spindle. Note 1: Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008; and Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009; reference Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003; for further guidance on accomplishing the related investigative actions. Restatement of Requirements of AD 2009-23-10, Amendment 39-16084 Repetitive Inspections, Related Investigative Actions, and Corrective Action for Certain Airplanes (i) For airplanes on which a carriage spindle having a serial number identified in Table 3 of Appendix A of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009, is installed: At the latest of the times specified in paragraphs (i)(1), (i)(2), and (i)(3) of this AD, as applicable, do a detailed inspection (or, as an option for the forward end of the spindle only, a borescope inspection technique may be used) of the spindle for corrosion and potential indications of corrosion of the carriage spindle, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. Do all applicable related investigative and corrective actions before further flight. Repeat the detailed inspection (or, as an option for the forward end of the spindle only, the borescope inspection) and related investigative actions (i.e., the gap-check or optional NDT ultrasonic inspection) at the applicable compliance times specified in paragraph 1.E. of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. (1) Within 30 days after November 24, 2009 (the effective date of AD 2009-23-10). (2) Within 90 days after the installation of a new HVOF-coated spindle identified in Table 3 of Appendix A of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. (3) Within 90 days after doing an inspection in accordance with Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008. New Requirements of This AD Terminating Action (j) Within 48 months after the effective date of this AD: Replace any HVOF-coated carriage spindle having a serial number identified in Table 2 or Table 3 of Appendix A of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009, with a non-HVOF-coated carriage spindle; or a serviceable HVOF-coated carriage spindle with an `R' suffix on the serial number; or a new or serviceable HVOF-coated carriage spindle having a serial number not identified in Table 2 or Table 3 of Appendix A of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009, without an `R' suffix on the serial number; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008; or Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009. Replacing all affected carriage spindles terminates the repetitive inspections required by this AD. Alternative Methods of Compliance (AMOCs) (k)(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: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440; fax (425) 917-6590. Or, e-mail information to 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (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 the Boeing Commercial Airplanes Organization Delegation 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 and the approval must specifically refer to this AD. Material Incorporated by Reference (l) You must use Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008; and Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009; as applicable; to do the actions required by this AD, unless the AD specifies otherwise. (1) The Director of the Federal Register previously approved the incorporation by reference of Boeing Service Bulletin 737-57A1304, Revision 1, dated August 11, 2009, on November 24, 2009 (74 FR 57564, November 9, 2009). (2) The Director of the Federal Register previously approved the incorporation by reference of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008, on August 5, 2008 (73 FR 42259, July 21, 2008). (3) 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. (4) 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. (5) 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 February 10, 2011. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 2011-3651 Filed 2-17-11; 8:45 am] BILLING CODE 4910-13-P

This AD results from reports of corrosion found on carriage spindles that are located on the outboard trailing edge flaps. The Federal Aviation Administration is issuing this AD to detect and correct corrosion of the carriage spindle, which could result in fracture. Fracture of both the inboard and outboard carriage spindles, in the forward ends through the large diameters, on a flap, could adversely affect the airplane's continued safe flight and landing.