# AD 2003-13-10: Hydromechanical unit (HMU) power lever angle (PLA) - Type: Airworthiness directive - Status: Historical - Products: 250-C30R/3, 250-C30R/3M, 250-C47B and 250-C47M - Effective: July 15, 2003 - Published: June 30, 2003, 68 FR 38590–38592 - Issued: June 19, 2003 - Issued as: Final rule; request for comments - Superseded by: [AD 2004-24-04](https://openairdocs.org/ad/2004-24-04) - Product type: Engine - Amendment: 39-13210 - Docket: 2003-NE-23-AD - Registered aircraft: 1,012 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/df/26/df265a7e1764047f2859d3e62c59a3cf41b634778d9a0f29e65f3b769e1be760 (from https://www.govinfo.gov/content/pkg/FR-2003-06-30/pdf/03-15993.pdf) - Federal Register: https://www.federalregister.gov/documents/2003/06/30/03-15993/airworthiness-directives-rolls-royce-corporation-formerly-allison-engine-company-allison-gas-turbine - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C1F66B6984ACE86686256D550059560A.0001 - DRS record last changed: August 7, 2025 - Page: https://openairdocs.org/ad/2003-13-10 ## Summary The FAA is adopting a new airworthiness directive (AD) for 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. This AD requires initial and repetitive electrical signal inspections of the hydromechanical unit (HMU) Power Lever Angle (PLA) potentiometer. This AD is prompted by an investigation by the National Transportation Safety Board (NTSB), which revealed that a potential undetected failure of the PLA potentiometer electrical signal could cause uncommanded and sudden changes in engine power. The actions specified in this AD are intended to prevent uncommanded and sudden changes in engine power. ## The airworthiness directive 1. The authority citation for part 39 continues to read as follows: 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 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. ### (a) Effective Date (a) This airworthiness directive (AD) becomes effective July 15, 2003. ### (b) Affected ADs (b) None. ### (c) 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. ### (d) 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 specified in this AD are intended to prevent uncommanded and sudden changes in engine power. ### (e) Compliance (e) Compliance with this AD is required as indicated, unless already done. ### (f) 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 15, 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. ### (h) 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. ### (j) 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. ### (k) 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. ### (l) Related Information (l) None. ## Rule preamble ### Dates Effective July 15, 2003. The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulations as of July 15, 2003. We must receive any comments on this AD by August 29, 2003. ### Addresses Use one of the following addresses to submit comments on this AD: • By mail: The Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-NE-23-AD, 12 New England Executive Park, Burlington, MA 01803-5299. • By fax: (781) 238-7055. • By e-mail: 9-ane-adcomment@faa.gov You may get the service information referenced in this AD from Rolls-Royce Corporation, P.O. Box 420, Indianapolis, IN 46206-0420; telephone (317) 230-6400; fax (317) 230-4243. You may examine the AD docket at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA. You may examine the service information 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. ### For further information contact Khailaa Hosny, Aerospace Engineer, Chicago Aircraft Certification Office, FAA, 2300 East Devon Avenue, Des Plaines, IL 60018-4696; telephone (847) 294-7134; fax (847) 294-7834. ### SUPPLEMENTARY INFORMATION This AD applies to Rolls-Royce Corporation models 250-C30R/3, -C30R/3M, -C47B, and -C47M turboshaft engines. This AD requires initial and repetitive electrical signal inspections of the HMU PLA potentiometer. This AD is prompted by an investigation by the NTSB into uncommanded and sudden changes in engine power on a Bell 407 helicopter on March 27, 2003. The NTSB investigation revealed that a potential undetected failure of the PLA potentiometer electrical signal, provided by the HMU of the full-authority digital electronic control (FADEC) system, could cause uncommanded and sudden changes in engine power. The actions specified in this AD are intended to prevent uncommanded and sudden changes in engine power. ### Relevant Service Information We have reviewed and approved the technical contents of 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, that describes procedures for inspecting the PLA potentiometer signal. ### Differences Between This Proposed AD and the Manufacturer's Service Information Although the combined SB CEB A-73-3103 (250-C30 engines) and CEB A-73-6030 (250-C47 engines), Revision 3, dated June 5, 2003, also includes 250-C40 engines, as CEB A-73-5021, the 250-C40 engine model is not affected by this AD because it is used in twin engine applications. ### FAA's Determination and Requirements of This AD The unsafe condition described previously is likely to exist or develop on other 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 of the same type design. Therefore, we are issuing this AD to prevent uncommanded and sudden changes in engine power. This AD requires an initial electrical signal inspection of the HMU PLA potentiometer within 50 flight hours after the effective date of this AD, but no later than July 15, 2003, and thereafter, repetitive inspections every 300 flight hours. You must do these inspections in accordance with the service information described previously. ### FAA's Determination of the Effective Date Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for prior public comment are impracticable, and that good cause exists for making this amendment effective in less than 30 days. ### Changes to 14 CFR Part 39—Effect on the AD On July 10, 2002, we issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs our AD system. This regulation now includes material that relates to special flight permits, alternative methods of compliance, and altered products. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions. ### Comments Invited This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 2003-NE-23-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it. If a person contacts us through a nonwritten communication, and that contact relates to a substantive part of this AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the AD in light of those comments. We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You may get more information about plain language at http://www.plainlanguage.gov. ### Regulatory Findings We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that the regulation: 1. Is not a “significant regulatory action” under Executive Order 12866; 2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and 3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-NE-23-AD” in your request. ### Adoption of the Amendment Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E1GL](https://openairdocs.org/tcds/E1GL): Rolls-Royce Corporation; names 4 of 23 models: 250-C47M, 250-C30R/3M, 250-C30R/3, 250-C47B ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 1,012 (0 by airframe model, 1,012 by engine model) - Makers: Bell 541, Bell Helicopter Textron Canada 365, MD Helicopters 16, Hiller 15, Mcdonnell Douglas Helicopter 14, Enstrom Helicopter 9, Sikorsky 8, Bell Helicopter Textron 7, Cessna 7, Beech 6 Models with the most aircraft: - [Rolls-Royce 250-C47B](https://openairdocs.org/engine/rolls-royce-250-c47b): 537 aircraft (engine model) - [Allison 250-C30 series](https://openairdocs.org/engine/allison-250-c30-series): 224 aircraft (engine model) - [Allison 250-C47 series](https://openairdocs.org/engine/allison-250-c47-series): 123 aircraft (engine model) - [Allison 250 series](https://openairdocs.org/engine/allison-250-series): 79 aircraft (engine model) - [Rolls-Royce 250-C47 series](https://openairdocs.org/engine/rolls-royce-250-c47-series): 16 aircraft (engine model) - [Allison 250-C47B](https://openairdocs.org/engine/allison-250-c47b): 15 aircraft (engine model) - [Rolls-Royce 250-C47M](https://openairdocs.org/engine/rolls-royce-250-c47m): 13 aircraft (engine model) - [Allison 250-C47M](https://openairdocs.org/engine/allison-250-c47m): 3 aircraft (engine model) - [Rolls-Royce 250-C30R/3](https://openairdocs.org/engine/rolls-royce-250-c30r-3): 1 aircraft (engine model) - [Rolls-Royce 250-C30R/3M](https://openairdocs.org/engine/rolls-royce-250-c30r-3m): 1 aircraft (engine model) All 11 models: https://openairdocs.org/ad/2003-13-10/models.md Every aircraft: https://openairdocs.org/ad/2003-13-10/aircraft.md ## Related documents - [AD 2004-24-04](https://openairdocs.org/ad/2004-24-04): Hydromechanical unit (HMU) Power Lever Angle (PLA) potentiometer · Rolls-Royce 250-C30R/3, 250-C30R/3M, 250-C47B and 1 more. Effective Jan 3, 2005. Supersedes this AD - [Proposed rule 2003-NE-23-AD](https://openairdocs.org/proposed/2003-NE-23-AD): Notice of proposed rulemaking (NPRM), published Jun 9, 2004 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.