E6-4702. Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

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 certain General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines. This proposed AD would require inspecting and reworking certain forward and aft center bodies of the long fixed core exhaust nozzle (LFCEN) assembly. This proposed AD results from reports of separation of LFCEN assembly forward and aft center bodies, due to high imbalance engine conditions during flight. We are proposing this AD to prevent the forward and aft center body of the LFCEN assembly from separating, leading to additional damage to the engine and airplane, possible damage to other airplanes, and to objects on the ground.

DATES:

We must receive any comments on this proposed AD by May 30, 2006.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You can get the service information identified in this proposed AD from General Electric Company via GE-Aviation, Attn: Distributions, 111 Merchant St., Room 230, Cincinnati, Ohio 45246, telephone [phone]; fax [phone].

You may examine the comments on this proposed AD in the AD docket on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Karen Curtis, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; telephone [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-2006-24145; Directorate Identifier 2006-NE-06-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://dms.dot.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 DOT Web site, anyone can find and read the comments in any of our dockets, including 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) or you may visit http://dms.dot.gov.

Examining the AD Docket

You may examine the docket that contains the proposal, any comments received and, any final disposition in person at the DOT Docket Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the Docket Management Facility receives them.

Discussion

Since 1975, 45 events of forward and aft center bodies separating from the engine have been reported. GE's investigation of the earlier events identified nut plate corrosion, and loose and missing fasteners as causes for the center body separations. In 1987, GE issued Service Bulletin (SB) No. CF6-50 S/B 78-216 to inspect for these conditions and add improved fasteners. In 2001, GE issued a Fleet Highlight and an All Operators Wire to remind operators of the availability of SB No. CF6-50 S/B 78-216. In 2003, GE issued SB No. CF6-50 S/B 78-241 for improved fastener torque.

In 2000, two separation events occurred. Investigation by GE and the FAA determined that bird strikes or other similar events can result in high engine imbalance conditions. These conditions can result in high stress and movement at the joint between the forward and aft center bodies, degrading the structural integrity of the joint, and separating the center bodies from the engine.

GE and the FAA determined that additional improvements are necessary to ensure structural integrity of the center body joints during high imbalance events. GE completed certification in 2004 of improved forward and aft center bodies. GE's improvement adds doublers, larger nuts and bolts, and higher strength corrosion resistant nut plates.

This condition, if not corrected, could result in the forward and aft center body of the LFCEN assembly separating, leading to additional damage to the engine and airplane, possible damage to other airplanes, and to objects on the ground.

Relevant Service Information

We have reviewed and approved the technical contents of GE SB No. CF6-50 S/B 78-0242, dated September 26, 2005, that identifies disassembly, inspection, rework, and reassembly procedures for the forward and aft center body, to add doublers, larger nuts and bolts, and higher strength corrosion resistant nut plates.

FAA's Determination and Requirements of the Proposed AD

We 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 will require reworking the forward and aft center bodies to add doublers, larger nuts and bolts, and higher strength corrosion resistant nut plates. This rework is required the next time the forward center body and aft center body are removed from the engine after the effective date of this proposed AD. The proposed AD would require you to use the service information described previously to perform these actions.

Costs of Compliance

We estimate that this proposed AD would affect 238 CF6-45 and CF6-50 series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 22 work hours per engine to perform the proposed actions, and that the average labor rate is $80 per work hour. Required parts would cost about $6,000 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $1,846,880.

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 regulation:

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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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-2006-24145; Directorate Identifier 2006-NE-06-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by May 30, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) CF6-45A, CF6-45A2, CF6-50C, CF6-50C1, CF6-50C2, CF6-50C2B, CF6-50C2D, CF6-50E, CF6-50E1, CF6-50E2, and CF6-50E2B series turbofan engines with long fixed core exhaust nozzle (LFCEN) assembly forward center body, part number (P/N) 1313M55G01 or G02, P/N 9076M28G09 or G10, and aft center body P/N 1313M56G01 or 9076M46G05, installed. These engines are installed on, but not limited to, Airbus A300 series, Boeing 747 series, McDonnell Douglas DC-10 series, and DC-10-30F (KC-10A, KDC-10) airplanes.

Unsafe Condition

(d) This AD results from reports of separation of LFCEN assembly forward and aft center bodies, due to high imbalance engine conditions during flight. We are issuing this AD to prevent the forward and aft center body of the LFCEN assembly from separating, leading to additional damage to the engine and airplane, possible damage to other airplanes, and to objects on the ground.

Compliance

(e) You are responsible for having the actions required by this AD performed the next time the forward and aft center bodies are removed from the engine after the effective date of this AD, unless the actions have already been done.

(f) Rework the forward and aft center bodies to add doublers, larger nuts and bolts, and higher strength corrosion resistant nut plates. Use paragraph 3, Accomplishment Instructions, of GE Service Bulletin No. CF6-50 S/B 78-0242, dated September 26, 2005, to identify the procedures required to do these actions.

Definition

(g) For the purposes of this AD, “next time the forward and aft center bodies are removed from the engine” includes when the center bodies are removed from the engine to take the engine off-wing.

Alternative Methods of Compliance

(h) 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.

Issued in Burlington, Massachusetts, on March 27, 2006.

Peter A. White,

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