2006-20-07: Adds an additional life limit for third- and fourth-stage turbine wheels

2006-20-07 Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison): Amendment 39-14776. Docket No. FAA-2005-23392; Directorate Identifier 2005-NE- 47-AD. Effective Date (a) This airworthiness directive (AD) becomes effective November 2, 2006. Affected ADs (b) None. Applicability (c) This AD applies to Rolls-Royce Corporation (RRC) models 250- C30, -C30G, -C30G/2, -C30M, -C30P, -C30R, -C30R/1, -C30R/3, -C30R/ 3M, -C30S, -C30U, -C40B, -C47B, and -C47M turboshaft engines, with a third-stage turbine wheel, part number (P/N) 6898663 or P/N 23065843 installed, or a fourth-stage turbine wheel, P/N 6892764 or P/N 23066744, installed. These engines are installed on, but not limited to, Bell 206L-3, Bell 206L-4, Bell 230, Bell 407, Bell 430, MDHI 369F, MDHI 369FF, MDHI 600N, and Sikorsky S-76A helicopters. Unsafe Condition (d) This AD results from analysis by RRC of failures of third- stage turbine wheels. We are issuing this AD to prevent loss of power, possible engine shutdown, or uncontained failure. Compliance (e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done. (f) Within 30 days after the effective date of this AD, record each time the third- and fourth-stage turbine wheels enter into the speed range between "Event Threshold" and "Maximum Overspeed Transient". Use paragraph 2.A. through 2.A.(5) of the Accomplishment Instructions and the applicable Figures 1 through 5 of RRC Alert Commercial Engine Bulletins (CEBs) No. CEB A-72-3272, No. CEB A-72-5048, and No. CEB A-72-6054 (combined in one document), all Revision 2, dated June 27, 2006, to determine the speed range. (g) Remove and retire any third-stage turbine wheel or fourth- stage turbine wheel after the sixth time the wheel enters into the speed range between "Event Threshold" and "Maximum Overspeed Transient". Third- and Fourth-Stage Turbine Wheel Life Limits (h) The retirement criteria in this AD are in addition to the existing third- and fourth-stage turbine wheel hour and cycle life limits. You must retire the wheels when you exceed any published life limit (transient speed excursions, hours, or cycles). Alternative Methods of Compliance (i) The Manager, Chicago Aircraft Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19. Related Information (j) None. Material Incorporated by Reference (k) You must use Rolls-Royce Corporation Alert Commercial Engine Bulletins No. CEB A-72-3272, No. CEB A-72-5048, and No. CEB A-72- 6054 (combined in one document), all Revision 2, dated June 27, 2006, to perform the actions required by this AD. The Director of the Federal Register approved the incorporation by reference of this service bulletin in accordance with5 U.S.C. 552(a) and 1 CFR part 51. Contact Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206-0420; telephone (317) 230-6400; fax (317) 230-4243 for a copy of this service information. You may review copies at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; 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/cfr/ibr-locations.html .