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Proposed Rule

Airworthiness Directives; General Electric Company (GE) CF6-80C2 and CF6-80E1 Series Turbofan Engines

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Start Preamble

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 CF6-80C2 and CF6-80E1 series turbofan engines with fuel manifold part numbers (P/Ns) 1303M31G12 and 1303M32G12 installed. This proposed AD would require removing and discarding the loop clamps that assemble the fuel manifold to the compressor rear frame (CRF) friction damper brackets, visually inspecting the fuel manifold for wear at each clamp location, and replacing the clamps with new, zero-time parts. This proposed AD results from fuel manifold vibration during engine operation that causes the loop clamps that assemble the manifold to the CRF to deteriorate. Fourteen fuel leak events occurred over the past several years. We are proposing this AD to prevent fuel leaks during engine operation that could result in an under-cowl fire.

DATES:

We must receive any comments on this proposed AD by November 6, 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: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
  • 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.

You may examine the comments on this proposed AD in the AD docket on the Internet at http://dms.dot.gov., or in Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE., Washington, DC 20590.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Robert Green, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA Start Printed Page 5138901803; telephone (781) 238-7754; fax (781) 238-7199.

End Further Info End Preamble Start Supplemental Information

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-2007-28413; Directorate Identifier 2007-NE-25-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 AD docket on the Internet at http://dms.dot.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 a pre-flight inspection in November 2002, a manifold fuel leak was found on a CF6-80C2B1F turbofan engine. This fuel leak resulted from fuel manifold vibration during engine operation, which caused the loop clamps that assemble the manifold to the CRF to deteriorate. The cushion on the loop clamp wore away resulting in the metal strip of the clamp rubbing into the fuel manifold. A fuel leak resulted. The high surface temperature of the CRF during engine operation could have ignited the leaking fuel resulting in an under-cowl fire.

In 2003, GE issued service bulletins for the CF6-80C2 and CF6-80E1series turbofan engines recommending repetitive visual inspection of the fuel manifolds at intervals of 4,500 flight-hours (FH). Despite these recommendations, five fuel leak events occurred in 2006; one resulting in an under-cowl fire on a CF6-80C2B6F turbofan engine. There have been three additional fuel leak events to date in 2007. A total of thirteen CF6-80C2 series turbofan engine fuel leaks (November 2002 through May 2007) and one CF6-80E1 fuel leak (January 2007) have been reported. Five of the recent events occurred within the 4,500 FH since the last inspection.

Because of the increased number of fuel leak events and the low FH intervals since the last inspection, this proposed AD would reduce the initial re-inspection FH interval, and would require replacing the fuel manifold loop clamps with new, zero-time parts at each inspection. This proposed AD is necessary to prevent fuel leaks during engine operation that could result in an under-cowl fire.

Differences Between the Proposed AD and the Manufacturer's Service Information

In the manufacturer's original service bulletins, GE recommends inspecting the fuel manifold for wear at 4,500 FH. However, the service bulletins do not recommend replacing the loop clamps at each inspection.

Because recent field events involving fuel leaks indicate a reduced inspection interval is required, this AD would require removing loop clamps and inspecting the fuel manifold according to the following schedule:

  • For engines previously inspected using GEAE service bulletins, SB 73-0226, dated March 5, 2003, for CF6-80C2 engines; or SB 73-0061, dated April 14, 2003, for CF6-80E1 engines, within 1,750 FH since-last-inspection.
  • If used loop clamps or clamps of unknown heritage were installed at last shop visit, within 1,750 FH since-last-shop-visit.
  • For first-run engines and engines with zero-time, new loop clamps installed at last shop visit, within 7,500 FH.
  • For affected engines that have already exceeded the 1,750 FH initial inspection threshold, within 4,500 FH of the last inspection or 4 months after the effective date of the AD, whichever comes first.

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 and discarding the loop clamps that assemble the fuel manifold to the compressor rear frame damper (CRF) friction damper brackets, visually inspecting the fuel manifold for wear at each loop clamp location, and replacing the clamps with new, zero-time parts.

Costs of Compliance

We estimate that this proposed AD would affect 350 CF6-80C2 series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 4 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 $162 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators for one manifold visual inspection and loop clamp replacement to be $168,700.

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: Start Printed Page 51390

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.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

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:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

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

General Electric Company: Docket No. FAA-2007-28413; Directorate Identifier 2007-NE-25-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by November 6, 2007.

Affected ADs

(b) None.

Applicability

(c) This AD applies to:

(1) GE CF6-80C2A1, -80C2A2, -80C2A3, -80C2A5, -80C2A8, -80C2A5F, -80C2B1, -80C2B2, -80C2B4, -80C2B6, -80C2B1F, -80C2B1F1, -80C2B1F2, -80C2B2F, -80C2B3F, -80C2B4F, -80C2B5F, -80C2B6F, -80C2B6FA, -80C2B7F, -80C2B8F, -80C2D1F, -80C2L1F, -80C2K1F turbofan engine models configured with fuel manifold part numbers (P/Ns) 1303M31G12 and 1303M32G12. These engines are installed on, but not limited to Boeing 747, 767, MD11, and Airbus A300 and A310 airplanes.

(2) This AD also applies to GE CF6-80E1A1, -80E1A2, -80E1A3, -80E1A4, -80E1A4/B turbofan engine models with fuel manifold P/N's 1303M31G12 and 1303M32G12. These engines are installed on Airbus A330 airplanes.

Unsafe Condition

(d) This AD results from fuel manifold vibration during engine operation that causes the clamps that assemble the manifold to the compressor rear frame (CRF) to deteriorate. We are issuing this AD to prevent fuel leaks. The high surface temperature of the CRF could ignite the leaking fuel resulting in an under-cowl fire.

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.

Removal and Replacement of Loop Clamps and Fuel Manifold Inspection Compliance Times

(f) Remove and discard the loop clamps, P/N J1220G10, that assemble the fuel manifold to the Compressor Rear Frame friction damper brackets, inspect the fuel manifold for wear at each clamp location as specified in paragraph (g) of this AD, and replace the loop clamps with new, zero-time parts at each inspection. Use the following schedule in Table 1 of this AD:

Table 1.—Inspection Schedule for Initial Inspections

If:Then replace clamps and inspect within:
(1) The engine was previously inspected using GEAE service bulletins, SB 73-0226, dated March 5, 2003, for CF6-80C2 engines; or SB 73-0061, dated April 14, 2003, for CF6-80E1 engines1,750 flight hours (FH) time-since-last-inspection (TSLI).
(2) Used loop clamps or clamps of unknown heritage were installed at last shop visit1,750 FH time-since-last-shop-visit.
(3) The engine is a first-run engine or is an engine with zero-time, new loop clamps previously installed7,500 FH since zero-time, new loop clamps were installed.
(4) The engine has already exceeded the 1,750 FH initial inspection threshold4,500 FH TSLI, or 4 months after the effective date of this AD, whichever occurs first.

Inspection of Fuel Manifold P/Ns 1303M31G12 and 1303M32G12

(g) Remove any tape applied to clamp locations. Visually inspect the full circumference of the manifold at each clamp location.

(h) If the fuel manifold shows any signs of wear, determine the depth of the wear as follows:

(1) Measure the outside diameter of the tube using a pinpoint micrometer adjacent to the worn area.

(2) Measure the worn area at the smallest diameter.

(3) Subtract the measurement of the worn tube diameter from the unworn diameter measurement. Allowable wear is 0.0035 inch.

(i) Before further flight, replace fuel manifolds with wear greater than 0.010 inch.

(ii) Replace fuel manifolds with wear greater than 0.0035 inch, but less than 0.010 inch, within 50 flight cycles.

Revise Air Carrier's Continuous Airworthiness Maintenance Program (CAMP) and Airworthiness Limitation Section (ALS)

(i) Within 30 days of the effective date of this AD, revise the air carrier's approved CAMP and ALS of Chapter 5 in the CF6-80C2 and CF6-80E1 Instructions for Continued Airworthiness to add:

(1) Repetitive inspections of fuel manifolds, P/Ns 1303M31G12 and 1303M32G12, as detailed in paragraphs (g) and (h) of this AD, at 7,500 FH intervals.

(2) Mandatory removal of loop clamps, P/N J1220G10, that assemble the fuel manifold, P/Ns 1303M31G12 and 1303M32G12, to the Compressor Rear Frame friction damper brackets, at each inspection.

(3) Replacement of loop clamps, P/N J1220G10, with new, zero-time parts, at each inspection.

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) GE service bulletins GEAE CF6-80C2 S/B 73-0226, dated March 5, 2003, and GEAE CF6-80E1 S/B 73-0061, dated April 14, 2003; and the following General Electric engine manuals pertain to the subject of this AD: CF6-80C2 Engine Manual GEK 92451; CF6-80C2L1F Engine Manual GEK 112213; CF6-80C2K1F Engine Manual GEK 112721; and CF6-80E1 Engine Manual GEK 99376.

(l) Contact Robert Green, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA, 01803; e-mail: robert.green@faa.gov; telephone (781) 238-7754; fax (781) 238-7199, for more information about this AD.

Start Signature
Start Printed Page 51391

Issued in Burlington, Massachusetts, on August 30, 2007.

Thomas A. Boudreau,

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

End Signature End Part End Supplemental Information

[FR Doc. E7-17682 Filed 9-6-07; 8:45 am]

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