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 includeit 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 commentsreceived 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
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:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
39.13 [Amended]
2. The FAA amends 39.13 by adding the following new airworthiness directive: