ACTION: Final rule.

SUMMARY: The FAA is superseding an existing airworthiness directive (AD) for Turbomeca Makila 1A, 1A1, and 1A2 turboshaft engines. That AD currently requires replacing certain digital electronic control units (DECUs) and electronic control units (ECUs) with modified DECUs and ECUs. This AD applies only to Makila 1A and 1A1 turboshaft engines, and requires replacing the selector-comparator board in the ECU with a board incorporating Turbomeca modification TU 250. This AD results from recent unexplained reversions of the ECU to the 65% N1 back-up mode. We are issuing this AD to prevent dual-engine continued operation at 65% N1 after reversion of the ECU to the 65% N1 back-up mode due to temporary loss of N2 speed signal, which could lead to inability to continue safe flight, emergency autorotation landing, or an accident. 

DATES: This AD becomes effective May 21, 2008. 

ADDRESSES: The Docket Operations office is located at Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590- 0001. 
You can get the service information identified in this AD from Turbomeca, 40220 Tarnos, France; telephone (33) 05 59 74 40 00; fax (33) 05 59 74 45 15. 

FOR FURTHER INFORMATION CONTACT: James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: james.lawrence@faa.gov; telephone (781) 238-7176; fax (781) 238-7199. 

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 by superseding AD 2002-15-05, Amendment 39-12833 (67 FR 49859, August 1, 2002), with a proposed AD. The proposed AD applies to Turbomeca Makila 1A and 1A1 turboshaft engines. We published the proposed AD in the Federal Register on November 15, 2007 (72 FR 64172). That action proposed to require replacing the selector-comparator board in the ECU with a board incorporating Turbomeca modification TU 250. 

Examining the AD Docket 

You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. 

Comments 

We provided the public the opportunity to participate in the development of this AD. We received no comments on the proposal or on the determination of the cost to the public. We also found we needed to clarify the unsafe condition statement from "We are issuing this AD to prevent dual-engine reversion of the ECU to the 65% N1 back-up mode, which could lead to inability to continue safe flight, emergency autorotation landing, or an accident'' to "We are issuing this AD to prevent dual-engine continued operation at 65% N1 after reversion of the ECU to the 65% N1 back-up mode due to temporary loss of N2 speed signal, which could lead to inability to continue safe flight, emergency autorotation landing, or an accident''. 

Conclusion 

We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD with the change described previously. 

Makila 1A2 Turboshaft Engines Excluded From This AD 

Although Makila 1A2 turboshaft engines, which were also listed in the previous AD, might be affected by this unsafe condition, EASA is reviewing the need to mandate a corrective action. Depending on the review outcome, we might address those engines in another AD action. 

Costs of Compliance 

We estimate that this AD will affect 10 Makila 1A and 1A1 turboshaft engines installed on helicopters of U.S. registry. We also estimate that it will take about 1 work-hour per engine to perform the actions, and that the average labor rate is $80 per work-hour. Required parts will cost about $3,500 per engine. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $35,800. 

Authority for This Rulemaking 

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. 
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, "General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. 

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 this AD: 
(1) Is not a "significant regulatory action'' under Executive Order 12866; 
(2) Is not a "significant rule'' under 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 at the address listed under ADDRESSES. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation safety, Safety. 

Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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. 

Sec. 39.13 [Amended] 

2. The FAA amends Sec. 39.13 by removing Amendment 39-12833 (67 FR 49859, August 1, 2002), and by adding a new airworthiness directive, Amendment 39-15469, to read as follows: