AD 2008-15-05 Airworthiness Directives; Boeing 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 Boeing Model 737-300, -400, and -500 series airplanes, certificated in any category.

Comply with this AD within the compliance times specified, unless already done. Inspection To Determine Affected Carriage Spindle (f) Within 30 days after the effective date of this AD, 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 (g) For airplanes on which any affected carriage spindle is installed: At the later of the times specified in paragraphs (g)(1) and (g)(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. Do all applicable related investigative actions 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 the service bulletin. (1) Within 30 days after the effective date of this AD. (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, references Boeing Alert Service Bulletin 737-57A1277, Revision 1, dated November 25, 2003, for further information on accomplishing the related investigative actions. Inspection Report (h) If any corrosion, cracking, or severed spindle is found during any inspection required by paragraph (g) of this AD: Within 10 days after the inspection, or within 10 days after the effective date of this AD, whichever occurs later, submit a report of the inspection results to the Manager, Airline Support, Boeing Commercial Airlines Group, as specified in Note 2 of paragraph 1.D., “Description,” of Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008. Information collection requirements contained in this AD have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120-0056. Optional Terminating Action (i) Replacement of an HVOF-coated carriage spindle with a non-HVOF coated carriage spindle in accordance with Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008, terminates the requirements of this AD for that carriage spindle only. Parts Installation (j) As of the effective date of this AD, an HVOF-coated spindle may be installed on an airplane provided the actions required by paragraph (g) of this AD are done on that spindle. Alternative Methods of Compliance (AMOCs) (k)(1) The Manager, Seattle ACO, FAA, ATTN: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440; fax (425) 917-6590; has the authority to approve AMOCs for this AD, if requested, using 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. Material Incorporated by Reference (l) You must use Boeing Alert Service Bulletin 737-57A1304, dated June 2, 2008, 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 July 10, 2008. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E8-16483 Filed 7-18-08; 8:45 am] BILLING CODE 4910-13-P

This AD results from a report of corrosion found on carriage spindles that are located on the outboard trailing edge flaps. We are 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 single flap, could adversely affect the airplane's continued safe flight and landing.