2003-13-10: Hydromechanical unit (HMU) power lever angle (PLA)

2003-13-10 Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison): Amendment 39-13210. Docket No. 2003-NE-23-AD. Effective Date (a) This airworthiness directive (AD) becomes effective July 15, 2003. Affected ADs (b) None. Applicability (c) This AD is applicable to Rolls-Royce Corporation (formerly Allison Engine Company, Allison Gas Turbine Division, and Detroit Diesel Allison) models 250-C30R/3, -C30R/3M, -C47B, and -C47M turboshaft engines. 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 was prompted by an investigation by the National Transportation Safety Board that revealed that a potential undetected failure of the Power Lever Angle (PLA) potentiometer electrical signal could cause uncommanded and sudden changes in engine power. The actions specifiedin 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 hydromechanical unit (HMU) PLA potentiometer, within 50 flight hours after the effective date of this AD, but no later than July 31, 2003, in accordance with paragraph 2.B. of the Accomplishment Instructions of Rolls-Royce Corporation combined service bulletin (SB) No. CEB A-73-3103 (250-C30 engines), or CEB A-73-6030 (250-C47 engines), Revision 3, dated June 5, 2003. (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 flight hours of the previous inspection, in accordance with section 2.B. of the Accomplishment Instructions of Rolls-Royce Corporation combined SB No. CEB A-73- 3103 (250-C30 engines), or CEB A-73-6030 (250-C47 engines), Revision 3, dated June 5, 2003. (i) Replace the HMU before further flight if the electrical signal inspection is unacceptable. Alternative Methods of Compliance (j) 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 (k) The inspections in this AD must be done in accordance with section 2.B. of the Accomplishment Instructions of Rolls-Royce Corporation combined Service Bulletin (SB) CEB A-73-3103 (250-C30 engines) and CEB A-73-6030 (250-C47 engines), Revision 3, dated June 5, 2003. 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. You may get a copy from Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206-0420; telephone (317) 230-6400; fax (317) 230-4243. 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 Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC. Related Information (l) None.