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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. FAA-2008-0827; Directorate Identifier 2008-NE-26-AD] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT). 

# ACTION:

Notice of proposed rulemaking (NPRM). 

# SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for GE CF6-80A series turbofan engines with certain stage 1 high-pressure turbine (HPT) rotor disks, installed. This proposed AD would require removal from service of those stage 1 HPT rotor disks within 30 days after the effective date of the AD. This proposed AD results from the FAA learning that those disks are susceptible to cracks developing in the bottoms of the dovetail slots. We are proposing this AD to prevent cracks developing in the bottoms of the dovetail slots that could propagate to a failure of the disk and cause an uncontained engine failure and damage to the airplane. 

# DATES:

We must receive any comments on this proposed AD by November 3, 2008. 

# ADDRESSES:

Use one of the following addresses to comment on this proposed AD. 
      -  Federal eRulemaking Portal:                          Go to                          http://www.regulations.gov                          and follow the instructions for sending your comments electronically.                     
      -  Mail:                          Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.                     
      -  Hand Delivery:                          Deliver to mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.                     
      -  Fax:                          (202) 493-2251.                     

# FOR FURTHER INFORMATION CONTACT:

                        Tara Chaidez, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803;                         *e-mail: tara.chaidez@faa.gov*;                         *telephone:*                         (781) 238-7773,                         *fax:*                         (781) 238-7199.                     

# SUPPLEMENTARY INFORMATION:

## Comments Invited 

                    We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under                     **ADDRESSES**                    . Include “Docket No. FAA-2008-0827; Directorate Identifier 2008-NE-26-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.                 

                    We will post all comments we receive, without change, to                     *http://www.regulations.gov*, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the                     **Federal Register**                     published on April 11, 2000 (65 FR 19477-78).                 

## 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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is the same as the Mail address provided in the                     **ADDRESSES**                     section. Comments will be available in the AD docket shortly after receipt.                 

## Discussion 

During discussions with GE, we recently learned that a population of stage 1 HPT rotor disks thought previously to have been retired, may still be in service. These disks are subject to cracks developing in the bottoms of the dovetail slots that could propagate to a failure of the disk. These stage 1 HPT rotor disks, part numbers (P/Ns) 1380M69G01/G02/G04/G05/G06; 9234M67G12/G13/G14/G15/G16; 9362M58G04; and 9367M45G01/G03/G05/G06/G07/G08 are not subject to rework or initial inspection. This proposed AD would require that all affected stage 1 HPT rotor disks be removed from service within 30 days after the effective date of the AD. This condition, if not corrected, could result in cracks developing in the bottoms of the dovetail slots that could propagate to a failure of the disk and cause an uncontained engine failure and damage to the airplane. 

## FAA's Determination and Requirements of the Proposed AD 

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which would require removing the affected stage 1 HPT rotor disks from service within 30 days after the effective date of the AD. 

## Costs of Compliance 

We estimate that this proposed AD would affect 3 out of 316 CF6-80A series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 1 work-hour per engine to perform the proposed actions, and that the average labor rate is $80 per work-hour. Required parts would cost about $300,000 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $900,240. 

## 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                           ( print page 51605)                        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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 proposed 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. Would 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 proposed AD. 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

## The Proposed Amendment 

Under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

**General Electric Company:**                                 Docket No. FAA-2008-0827; Directorate Identifier 2008-NE-26-AD.                             

## Comments Due Date 

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by November 3, 2008. 

## Affected ADs 

(b) None. 

## Applicability 

(c) This AD applies to General Electric Company (GE) CF6-80A series turbofan engines with any of the following stage 1 high-pressure turbine (HPT) rotor disk part numbers (P/Ns), installed: 

(1) 1380M69G01; 1380M69G02; 1380M69G04; 1380M69G05; or 1380M69G06; or 

(2) 9234M67G12; 9234M67G13; 9234M67G14; 9234M67G15; or 9234M67G16; or 

(3) 9362M58G04; or 

(4) 9367M45G01; 9367M45G03; 9367M45G05; 9367M45G06; 9367M45G07; or 9367M45G08. 

(d) These CF6-80A series turbofan engines are installed on, but not limited to, Airbus A310-200 series and Boeing 767-200 series airplanes. 

## Unsafe Condition 

(e) This AD results from the FAA learning that those discs are susceptible to cracks developing in the bottoms of the dovetail slots. We are issuing this AD to prevent cracks developing in the bottoms of the dovetail slots that could propagate to a failure of the disk and cause an uncontained engine failure and damage to the airplane. 

## Compliance 

(f) You are responsible for having the actions required by this AD performed within 30 days after the effective date of this AD, unless the actions have already been done. 

(g) Remove from service HPT stage 1 rotor disks identified by P/N in paragraph (c) of this AD. 

## Prohibition of HPT Stage 1 Rotor Disks 

(h) After the effective date of this AD, do not install any of the HPT stage 1 rotor disks, listed by P/N in paragraph (c) of this AD into any engine. 

## Alternative Methods of Compliance 

(i) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD, if requested using the procedures found in 14 CFR 39.19. 

## Related Information 

                                (j) Contact Tara Chaidez, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803;                                 *e-mail: tara.chaidez@faa.gov*;                                 *telephone:*                                 (781) 238-7773,                                 *fax:*                                 (781) 238-7199, for more information about this AD.                            

Issued in Burlington, Massachusetts, on August 28, 2008. 

Marc J. Bouthillier, 

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

[FR Doc. E8-20497 Filed 9-3-08; 8:45 am] 

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