2004-24-04: Hydromechanical unit (HMU) Power Lever Angle (PLA) potentiometer

2004-24-04 Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison): Amendment 39-13880. Docket No. 2003-NE-23-AD. Supersedes AD 2003-13-10, Amendment 39-13210. Effective Date (a) This AD becomes effective January 3, 2005. Affected ADs (b) This AD supersedes AD 2003-13-10. Applicability (c) This AD applies to Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) (RRC) models 250-C30R/3, -C30R/3M, -C47B, and -C47M turboshaft engines that have a hydromechanical unit (HMU) with a part number (P/N) listed in 1.A. Group A of RRC Alert Commercial Engine Bulletins (ACEB) No. CEB A-73-3103, Revision 4, dated December 2, 2003; and No. CEB A-73-6030, Revision 4, dated December 2, 2003. These engines are installed on, but not limited to, Bell OH-58D, Bell Helicopter Textron 407, Boeing AH/MH-6M, and MD Helicopters Inc. 600N helicopters. Unsafe Condition (d) This AD results from the manufacturer releasing a redesigned HMU that has a dual-element potentiometer. The actions specified in this AD are intended to prevent uncommanded and sudden changes in engine power. Compliance (e) Compliance with this AD is required as indicated, unless already done. Initial Inspection (f) Perform an initial electrical signal inspection of the HMU Power Lever Angle (PLA) potentiometer, within 300 flight hours (FH) after the effective date of this AD. Use paragraphs 2.B. through 2.B.(8) and 2.B.(10) of the Accomplishment Instructions of RRC ACEB No. CEB A-73-3103, Revision 4, dated December 2, 2003; or No. CEB A- 73-6030, Revision 4, dated December 2, 2003; to perform the inspection. (g) Replace the HMU before further flight if the electrical signal inspection result is unacceptable. Repetitive Inspections (h) Thereafter, perform repetitive electrical signal inspections of the HMU PLA potentiometer within 300 FH of the last inspection. Use paragraphs 2.B. through 2.B.(8) and 2.B.(10) of the Accomplishment Instructions of RRC ACEB No. CEB A-73-3103, Revision 4, dated December 2, 2003; or No. CEB A-73-6030, Revision 4, dated December 2, 2003; to perform the inspection. (i) Replace the HMU before further flight if the electrical signal inspection result is unacceptable. Mandatory Terminating Action (j) Replace the HMU with an HMU that has a P/N not specified in this AD within 600 FH after the effective date of this AD, or January 31, 2005, whichever occurs earlier. Replacing the HMU with an HMU that has a P/N not specified in this AD terminates the repetitive inspection requirement specified in paragraph (h) of this AD. Alternative Methods of Compliance (k) Alternative methods of compliance must be requested in accordance with 14 CFR part 39.19, and must be approved by the Manager, Chicago Aircraft Certification Office, FAA. Material Incorporated by Reference (l)You must use the Rolls-Royce Corporation Alert Commercial Engine Bulletins (ACEBs) listed in Table 1 of this AD to perform the inspections required by this AD. The Director of the Federal Register approved the incorporation by reference of the documents listed in Table 1 of this AD in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. You can get a copy from Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206-0420; telephone (317) 230-6400; fax (317) 230-4243. You can 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/code_of_federal_regulations/ibr_locations.html. Table 1 follows: Table 1.--Incorporation by Reference Service bulletin Page number(s) shown on the page Revision level shown on the page Date shown on the page CEB A-73-3103, Total Pages: 20 All 4 December 2, 2003. CEB A-73-6030, Total Pages: 20 All 4 December 2, 2003. Related Information (m) None.