Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on March 25, 2010 (75 FR 14379). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states that:
Following a review of operational data of the Tay 651-54 engine, it has been found that the actual stress levels in the Tay 651-54 engine High Pressure Compressor (HPC) stages 1, 3, 6, 7 and 12 discs were higher than those originally assumed and therefore the approved lives needed to be reduced.
As Tay 651-54 service run HPC discs may be installed on Tay 620- 15 and Tay 650-15 engine models, it is necessary to reduce the maximum approved lives of the affected HPC disc serial numbers installed on Tay 620-15 and Tay 650-15 engines as well.
The approved lives of the affected HPC stages 1, 3, 6, 7 and 12 discs specifiedin this Airworthiness Directive supersede the approved lives given in the Time Limits Manuals, Chapter 05-10-01.
Exceeding of the approved life limits could potentially result in non-contained disc failure.
Comments
We gave the public the opportunity to participate in developing this AD. We received no comments on the NPRM or on the determination of the cost to the public.
Conclusion
We reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed.
Costs of Compliance
Based on the service information, we estimate that this AD would affect about 10 products of U.S. registry. We also estimate that it would take about 1 work-hours per product to comply with this AD. The average labor rate is $85 per work-hour. Required parts would cost about $100,000 per product. Based on these figures, we estimate the cost of the AD on U.S. operators to be $1,000,850.
Authority for This Rulemaking
Title 49of 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 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 this AD:
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 regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.
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 (phone (800) 647-5527) is provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.
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 FAA 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 adding the following new AD: