ACTION: Final rule.

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for CFM International, S.A. CFM56-7B series turbofan engines. This AD requires revising the Airworthiness Limitations Section (ALS) in the Engine Shop Manual (ESM) and the air carrier's approved continuous airworthiness maintenance program (CAMP) to add mandatory inspections of certain low pressure turbine rear frames (TRFs) to the ALS or CAMP. This AD results from a refined lifing analysis by the engine manufacturer that shows the need to identify an initial threshold for inspecting certain TRFs. We are issuing this AD to prevent failure of the TRF from low-cycle fatigue cracks. Failure of the TRF could result in engine separation from the airplane, which could lead to loss of control of the airplane. 

DATES: This AD becomes effective March 10, 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. 

FOR FURTHER INFORMATION CONTACT: Antonio Cancelliere, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone (781) 238-7751; fax (781) 238-7199. 

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 with a proposed AD. The proposed AD applies to CFM International, S.A. CFM56-7B series turbofan engines. We published the proposed AD in the Federal Register on April 23, 2007 (72 FR 20075). That action proposed to require revising the ALS in the Engine Shop Manual and the air carrier's approved continuous airworthiness maintenance program (CAMP) to add mandatory inspections of certain low pressure turbine rear frames (TRFs) to the ALS or CAMP. 

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 have considered the comments received. 

Update Table for Figure 805 

Delta Airlines requests that we change the wording in the table for Figure 805 because CFM International updated CFM56-7B Engine Shop Manual section 05-21-03, with Temporary Revision 05-0080, dated December 5, 2006. We agree and have reworded the table for Figure 805 to reflect wording used by the original equipment manufacturer (OEM). For clarification, we also moved the titles for Figures 806 and 807 to the beginning of the figures. 

Guidance on Future Revisions 

Delta Airlines also suggests that we provide guidance on making future OEM revisions to ESM section 05-21-03 while maintaining compliance with the AD. We disagree. The information contained within sections (j) and (k) of the AD is adequate. Any future OEM changes to the ALS that affect compliance with this AD will require an AD revision or supersedure, depending on the specific situation. Airlines should make changes to items outside of this specific area and incorporate them into their ESM or CAMP per their normal procedures. 

Add Part Numbers (P/Ns) to Applicability 

Finally, Delta Airlines requests that we add P/Ns 340-166-251-0, 340-166-252-0 and 340-166-253-0 to the Applicability section and clarify whether these P/Ns will be applicable to the business jet application as well as the commercial application. We disagree. The intent of this AD is to make operators aware of the life limit/ mandatory inspections recently introduced by CFM International in the Airworthiness Limitations Section of the CFM56-7B Engine Shop Manual that affect P/Ns that were not previously limited. Ignoring these new limitations could create a potentially unsafe condition. The P/Ns listed above were subject to a life limit and mandatory inspection when first introduced to the ESM, therefore, there is no potential unsafe condition. Business jet and commercial engine model applicability of the new P/Ns is as listed in the ESM. 

Conclusion 

We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. 

Costs of Compliance 

We estimate that this AD will affect 1,228 engines installed on airplanes of U.S. registry. While the cost of making the manual change is negligible, the resulting inspections must be discussed. Since life extensions are possible on condition, the cost of the AD is limited to performing TRF inspections. We estimate that it will take about 3.0 work-hours per engine to perform the actions, including the TRF inspections, and that the average labor rate is $80 per work- 
hour. No parts are required. Based on these figures, we estimate the total cost of the AD to U.S. operators to be $294,720. 

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 adding the following new airworthiness directive: