E7-10512. Airworthiness Directives; General Electric Company Aircraft Engine Group (GEAE) CF6-45A Series, CF6-50A, CF6-50C Series and CF6-50E 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 GEAE CF6-45A, 45A2, -50A, -50C, -50CA, -50C1, -50C2, -50C2B, -50C2D, -50C2F, -50C2R, -50E, -50E1, -50E2, and -50E2B turbofan engines. This proposed AD would require replacing the compressor discharge pressure (CDP) restoring spring assembly on certain main engine controls (MECs) or re-marking MECs that already incorporate GEAE Service Bulletin (SB) No. CF6-50 S/B 73-0119, dated March 21, 2005. This proposed AD results from reports of five events involving fractured CDP restoring spring assemblies. We are proposing this AD to prevent loss of engine thrust control that could lead to loss of control of the airplane.

DATES:

We must receive any comments on this proposed AD by July 30, 2007.

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:

Tara Chaidez, Aerospace Engineer, Engine Certification Office, FAA, Engine & 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-2006-25239; Directorate Identifier 2006-NE-23-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.).

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 Offices 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

We received reports of five field events since 2002, which involved fractured CDP restoring spring assemblies. Four events resulted in in-flight shutdowns, and one event occurred during ground operation and resulted in an engine shutdown.

Before 1996, the manufacturer of the spring assemblies welded some spring assemblies such that the gap between the spring and the curved spring seat exceeded 0.002 inch. Analysis shows that spring assemblies with gaps greater than 0.002 inch have high stresses in the spring and can fatigue in the heat affected zone of the weld.

Fracture of the spring assembly could cause excessive fuel flow from the MEC, which could result in an uncommanded increase in engine thrust with loss of throttle control. This condition, if not corrected, could result in loss of engine thrust control that could lead to loss of control of the airplane.

Relevant Service Information

We have reviewed and approved the technical contents of GEAE SB No. CF6-50 S/B 73-0119, Revision 02, dated March 9, 2007, that describes procedures for replacing the CDP restoring spring assembly and re-marking the MEC data plate, and GEAE SB No. CF6-50 S/B 73-0120, dated March 21, 2007 that describes procedures for replacing the CDP restoring spring assembly.

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 replacing the CDP restoring spring assembly on certain MECs and re-marking MECs that already incorporate GEAE SB No. CF6-50 S/B 73-0119, dated March 21, 2005 or GEAE SB No. CF6-50 S/B 73-0119, Revision 01, dated May 26, 2006. 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 756 GEAE CF6-45A, -50C, and -50E series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 40 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 $1,787 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $3,770,172.

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-2006-25239; Directorate Identifier 2006-NE-23-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by July 30, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company Aircraft Engine Group (GEAE) CF6-45A, 45A2, -50A, -50C, -50CA, -50C1, -50C2, -50C2B, -50C2D -50C2F, -50C2R, -50E, -50E1, -50E2, and -50E2B turbofan engines that have a main engine control (MEC) with a part number (P/N) specified in Table 1 of this AD installed. These engines are installed on, but not limited to, Airbus A300 series airplanes, McDonnell Douglas DC-10, KC-10, and MD-10 series airplanes, and Boeing 747 series airplanes.

Table 1.—Affected Woodward and GEAE P/Ns for MECs by Engine Model Series

Engine model series	Woodward P/N	GEAE P/N
CF6-50A, -50C, -50CA, -50C1, -50C2, -50C2B, -50C2D, -50C2F, -50C2R	8062-275 8062-279 8062-287	9070M55P42 9070M55P44 9070M55P49
	8062-289	9070M55P51
	8062-819	9070M55P101
	8062-822	9070M55P102
	8062-824	9070M55P103
	8062-823	9070M55P104
	8062-826	9070M55P105
	8062-827	9070M55P106
	8062-828	9070M55P107
	8062-829	9070M55P108
CF6-45A, -45A2, -50E, -50E1, -50E2, -50E2B	8062-276 8062-280 8062-290	9187M29P10 9187M29P11 9187M29P14
	8062-291	9187M29P15
	8062-817	9187M29P100
	8062-820	9187M29P101
	8062-896	9187M29P22
	8062-897	9187M29P23
	8062-898	9187M29P20
	8062-899	9187M29P21

(d) This AD results from reports of five events involving fractured compressor discharge pressure (CDP) restoring spring assembly. We are issuing this AD to prevent loss of engine thrust control that could lead to loss of control of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

Replacing the CDP Restoring Spring Assembly on CF6-50A Engines and -50C Series Engines

(f) For CF6-50A model engines and -50C series engines that have an MEC that has a P/N listed in Table 1 of this AD, replace the CDP restoring spring assembly as follows in Table 2 of this AD:

Table 2.—Compliance Schedule for CF6-50A and -50C Engines

If the CDP restoring spring assembly in your MEC	Then	By	Use
(1) Was already replaced using GEAE CF6-50 S/B 73-0119, dated March 21, 2005	Re-mark the MEC	The next time the MEC is routed for repair such as the next MEC shop visit	Paragraph 3.A. of the Accomplishment Instructions of SB No. CF6-50 S/B 73-0119, Revision 02, dated March 9, 2007.
(2) Was already replaced within 10,000 or fewer hours time-in-service (TIS) before the effective date of this AD, and the replacement spring assembly (P/N 3018-248) had zero hours TIS	Replace the spring assembly and re-mark the MEC	The first MEC shop visit or engine shop visit after the MEC exceeds 10,000 hours TIS, but do not exceed 20,000 hours TIS	Paragraph 3.A. of the Accomplishment Instructions of SB No. CF6-50 S/B 73-0119, Revision 02, dated March 9, 2007.
(3) Has more then 10,000 hours TIS	Replace the spring assembly and re-mark the MEC	The next MEC shop visit or engine shop visit whichever occurs first	Paragraph 3.A. of the Accomplishment Instructions of SB No. CF6-50 S/B 73-0119, Revision 02, dated March 9, 2007.

Replacing the CDP Restoring Spring Assembly on CF6-45A and -50E Series Engines

(g) For CF6-45A series and -50E series engines that have an MEC that has a P/N listed in Table 1 of this AD, replace the CDP restoring spring assembly as follows in Table 3 of this AD:

Table 3.—Compliance Schedule for CF6-45A and -50E Engines

If the CDP restoring spring assembly in your MEC	Then	By	Use
(1) Was already replaced within 10,000 or fewer hours time-in-service (TIS) before the effective date of this AD, and the replacement spring assembly (P/N 3018-248) had zero hours TIS	Replace the spring assembly and re-mark the MEC	The first MEC shop visit or engine shop visit after the MEC exceeds 10,000 hours TIS, but do not exceed 20,000 hours TIS	Paragraph 3.A. of the Accomplishment Instructions of SB No. CF6-50 S/B 73-0120, dated March 21, 2007.
(2) Has more then 10,000 hours TIS	Replace the spring assembly and re-mark the MEC	The next MEC shop visit or engine shop visit whichever occurs first	Paragraph 3.A. of the Accomplishment Instructions of SB No. CF6-50 S/B 73-0120, dated March 21, 2007.

Definition

(h) For the purpose of this AD, a shop visit is induction of the engine or MEC into the shop for any cause.

Installation Prohibition

(i) After the effective date of the AD, do not install an MEC that:

(1) Has not complied with SB No. CF6-50 S/B 73-0119, Revision 02, dated March 9, 2007 or earlier revision, or SB No. CF6-50 S/B 73-0120, dated March 21, 2007, or,

(2) Has not had the CDP restoring spring replaced with a spring assembly, P/N 3018-248, or FAA-approved equivalent spring assembly, within the previous 10,000 hours of MEC operation.

Alternative Methods of Compliance

(j) 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

(k) None.

Issued in Burlington, Massachusetts, on May 23, 2007.

Fran A. Favara,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.