2010-26312. Airworthiness Directives; General Electric Company (GE) CF6-45 Series and CF6-50 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for GE CF6-45 and CF6-50 series turbofan engines. This proposed AD would require performing a fluorescent penetrant inspection (FPI) of the stage 3 low-pressure turbine (LPT) rotor at every shop visit at which the LPT module is separated from the engine. This proposed AD results from seven reports of uncontained failures of LPT stage 3 disks and eight reports of cracked LPT stage 3 disks found during shop visit inspections. We are proposing this AD to prevent LPT rotor separation, which could result in an uncontained engine failure and damage to the airplane.

DATES:

We must receive any comments on this proposed AD by December 20, 2010.

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: [phone].

FOR FURTHER INFORMATION CONTACT:

Christopher J. Richards, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; phone: [phone]; fax: [phone].

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-2010-0998; Directorate Identifier 2010-NE-29-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 [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

Since July 2008, we have received seven reports of uncontained failures of LPT stage 3 rotor disks and eight reports of cracked LPT rotor stage 3 disks found during shop visit inspections. Our investigation revealed that certain part number LPT stage 3 rotor disks might fail due to circumferential cracking of the forward cone body (forward spacer arm) of the LPT stage 3 disk when exposed to core engine (N2) vibrations. On June 4, 2010, we issued AD 2010-12-10 that requires a separate set of corrective actions. Those actions, along with this proposed AD, reduce the likelihood of further uncontained engine failures. This condition, if not corrected, could result in critical life-limited rotating engine part failure, which could result in 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 performing a fluorescent penetrant inspection at every shop visit when the LPT module is separated from the engine.

Interim Action

These actions are interim actions and we may take further rulemaking actions in the future.

Costs of Compliance

We estimate that this proposed AD would affect 387 engines installed on airplanes of U.S. registry. We also estimate that it would take about 7 work-hours per engine to perform the proposed actions, and that the average labor rate is $85 per work-hour. No parts would be required. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $230,265.

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 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

[Amended]

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

General Electric Company: Docket No. FAA-2010-0998; Directorate Identifier 2010-NE-29-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by December 20, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) CF6-45A, CF6-45A2, CF6-50A, CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-50C2-F, CF6-50C2-R, CF6-50E, CF6-50E1, and CF6-50E2 series turbofan engines, with a low-pressure turbine (LPT) rotor stage 3 disk that has a part number (P/N) listed in Table 1 of this AD installed:

Table 1—LPT Rotor Stage 3 Disk P/Ns

1473M90P01	1473M90P02	1473M90P03	1473M90P04
1479M75P01	1479M75P02	1479M75P03	1479M75P04
1479M75P05	1479M75P06	1479M75P07	1479M75P08
1479M75P09	1479M75P11	1479M75P13	1479M75P14
9061M23P06	9061M23P07	9061M23P08	9061M23P09
9061M23P10	9061M23P12	9061M23P14	9061M23P15
9061M23P16	9224M75P01

These engines are installed on, but not limited to, Boeing 747-200B series, -200C series, and -200F series, 747-300 series airplanes; McDonnell Douglas DC-10-15, -30, and -30F, MD-10-30, KC-10A, and KDC-10 airplanes; and Airbus A300 series airplanes.

Unsafe Condition

(d) This AD results from seven reports of uncontained failures of LPT stage 3 disks and eight reports of cracked LPT stage 3 disks found during shop visit inspections. We are issuing this AD to prevent LPT rotor separation, which could result in an uncontained engine failure and damage to the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed at each shop visit after the effective date of this AD, at which the LPT module is separated from the engine.

Cleaning the LPT Stage 3 Disk

(f) Clean the LPT stage 3 disk, using a wet-abrasive blast to eliminate residual or background fluorescence. You can find guidance on cleaning the disk in the cleaning procedure of CF6-50 Engine Manual, GEK 50481 72-57-02.

Inspecting the LPT Stage 3 Disk

(g) Perform a fluorescent penetrant inspection (FPI) of the inner diameter of the forward cone body (forward spacer arm) of the LPT stage 3 disk. You can find guidance on performing the FPI in the CF6-50 Engine Manual, GEK 50481 72-57-02.

(h) If a crack or a band of fluorescence is present, remove the disk from service.

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 Christopher J. Richards, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; phone: [phone]; fax: [phone], for more information about this AD.

Issued in Burlington, Massachusetts, on October 8, 2010.

Peter A. White,

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