AD 2005-23-03 Airworthiness Directives; Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, and 25F Airplanes

Models named: 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Learjet Model 23, 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D, and 25F airplanes, certificated in any category; having serial numbers 23-003 through 23-099 inclusive, 24-100 through 24-284 inclusive, and 25-003 through 25-153 inclusive.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Replacement (f) Within 60 days after the effective date of this AD, replace the spherical accumulator having part number (P/N) 2380025-() or P/N 2380167-() with a new cylindrical accumulator having P/N 2497202-801, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A23/24/25-29-4, Revision 1, dated January 17, 2005. Concurrent Action (g) For airplanes having serial numbers 23-003 through 23-014 inclusive: Prior to or concurrently with the actions in Bombardier Alert Service Bulletin A23/24/25-29-4, Revision 1, dated January 17, 2005, relocate the accumulator pressure gauge in accordance with Learjet Service Kit SK23-215, dated April 4, 1966. Parts Installation (h) As of the effective date, no spherical accumulator having P/N 2380025-() or P/N 2380167-() may be installed on any airplane. Previous Actions (i) Replacements done before the effective date of this AD in accordance with Bombardier Alert Service Bulletin A23/24/25-29-4, dated August 20, 2004, are acceptable for compliance with the requirements of paragraph (f) of this AD. No Reporting Required (j) Although the service bulletin referenced in this AD specifies to submit certain information to the manufacturer, this AD does not include that requirement. Alternative Methods of Compliance (AMOCs) (k)(1) The Manager, Wichita Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office. Material Incorporated by Reference (l) You must use Bombardier Alert Service Bulletin A23/24/25-29-4, Revision 1, dated January 17, 2005; and Learjet Service Kit SK23-215, dated April 4, 1966; as applicable, to perform the actions that are required by this AD, unless the AD specifies otherwise. (The issue date of Learjet Service Kit SK23-215 is located only on the first and last pages of the document.) The Director of the Federal Register approved the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Contact Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942, for a copy of this service information. You may review copies at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, Nassif Building, Washington, DC; on the Internet at http://dms.dot.gov ; or at the National Archives and Records Administration (NARA). For information on the availability of this material at the 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 October 26, 2005. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 05-22220 Filed 11-10-05; 8:45 am] BILLING CODE 4910-13-P

This AD results from reports of the failure of two thrust reverser accumulators (which are similar to the main hydraulic system's accumulator) and fatigue cracks found on four thrust reverser accumulators. We are issuing this AD to prevent failure of the spherical accumulator for the main hydraulic system, due to fatigue cracking on the threads, which could result in the loss of hydraulic power, damage to the surrounding airplane structure, and loss of airplane control. The failure of the accumulator could also result in injury to any persons in the surrounding area. The loss of hydraulic fluid could also leak onto a potential source of ignition and result in a consequent fire.