E6-17742. Airworthiness Directives; General Electric Company (GE) CF6-80C2B 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 GE CF6-80C2B series turbofan engines with electronic control units (ECUs), installed on Boeing 747 and 767 airplanes. This proposed AD would require installing software version 8.2.Q1 to the engine ECU, which increases the margin to engine flameout. This proposed AD results from reports of engine flameout events during flight, including reports of events where all engines simultaneously experienced a flameout or other adverse operation. We are proposing this AD to provide increased margin to flameout and to minimize the potential of an all-engine flameout event, due to ice accretion and shedding during flight.

DATES:

We must receive any comments on this proposed AD by December 26, 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 Lockheed Martin Technology Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 45215, 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:

John Golinski, 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-2006-25738; Directorate Identifier 2006-NE-27-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

GE CF6-80C2 and CF6-80E1 series turbofan engines continue to experience flameout events that are due to ice accretion and shedding during flight. Though the investigation is not yet complete, exposure to ice crystals during flight is believed to be associated with these flameout events. We have received reports of 32 airplane events, including reports of multi-engine events where all engines on the airplane simultaneously experienced a flameout or other adverse operation. Some of these events had high pressure compressor blade damage that may have been caused by impact with shedding ice. In all events, the engines restarted and continued to operate normally for the remainder of the flight.

We view an all-engine flameout event as an unsafe condition particularly for low-altitude events, or other factors that might result in the inability to restart the engines and regain control of the airplane.

Since some aspects of this problem are not completely understood, this proposed AD is considered an interim action due to GE's on-going investigation. Future AD action might become necessary based on the results of the investigation and field experience.

This proposed AD addresses only the CF6-80C2B series turbofan engines with ECUs, installed on Boeing 747 and 767 airplanes. The remaining CF6-80C2 and CF6-80E1 series engines are being studied by GE, and we may have future AD actions when studies are finished.

This condition of insufficient margin to engine flameout due to ice accretion and shedding during flight, if not addressed, could result in an all-engine flameout event during flight.

Relevant Service Information

We have reviewed and approved the technical contents of GE Service Bulletin (SB) No. CF6-80C2 S/B 73-0339, dated November 17, 2005. That SB describes procedures for installing software version 8.2.Q1 to the ECU. Software version 8.2.Q1 modifies the variable bleed valve schedule, which will provide an increased margin to flameout. This increased margin is expected to reduce the rate of flameout occurrences due to ice accretion and shedding during flight.

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

Although GE SB No. CF6-80C2 S/B 73-0339, dated November 17, 2005, recommends the incorporation of software version 8.2.Q1 at the next shop visit of the ECU, this proposed AD would:

• Require a more aggressive compliance schedule for incorporating the software; and
• Add a compliance requirement for affected engines installed on Boeing 767 airplanes, which the SB does not require.

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:

• For Boeing 767 airplanes, within 24 months after the effective date of this AD, installing software version 8.2.Q1 to the ECU on at least one of airplane's affected turbofan engines, and
• For all other affected turbofan engines, installing software version 8.2.Q1 to the ECU at the next shop visit of the ECU or engine, whichever occurs first, not to exceed five years after the effective date of this proposed AD.

This software change will provide increased margin to flameout and reduce the rate of flameout occurrences due to ice accretion and shedding during flight. The proposed AD would require you to use the GE service bulletin described previously to perform these actions.

Interim Action

These actions are interim actions due to the on-going investigation. We may take further rulemaking actions in the future, based on the results of the investigation and field experience.

Costs of Compliance

We estimate that this proposed AD would affect 293 CF6-80C2B series turbofan engines with ECUs installed on Boeing 747 and 767 airplanes of U.S. registry. We estimate that 73 engines would have the software installed at ECU overhaul, 147 engines would have the software installed during ECU repair, and 73 engines would have the software installed, not due to ECU overhaul or repair. It would take about six work-hours per engine to perform the proposed actions (ECU overhauls not included) and the average labor rate is $80 per work-hour. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $283,740. GE may provide the software at no cost to the operators, and reimburse the six work-hours labor cost until December 31, 2010.

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 engines 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-2006-25738; Directorate Identifier 2006-NE-27-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by December 26, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to General Electric Company (GE) CF6-80C2B1F, -80C2B2F, -80C2B4F, -80C2B5F, -80C2B6F, -80C2B6FA, -80C2B7F, and -80C2B8F turbofan engines with electronic control units (ECUs), installed on Boeing 747 and 767 airplanes.

Unsafe Condition

(d) This AD results from reports of engine flameout events during flight, including reports of events where all engines simultaneously experienced a flameout or other adverse operation. We are issuing this AD to provide increased margin to flameout and to minimize the potential of an all-engine flameout event, due to ice accretion and shedding during flight. Exposure to ice crystals during flight is believed to be associated with these flameout events.

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.

Engine ECU Software Installation

(f) For Boeing 767 airplanes, within 24 months after the effective date of this AD, install software version 8.2.Q1 to the engine ECU on at least one of the airplane's affected turbofan engines.

(g) For all other affected turbofan engines, install software version 8.2.Q1 to the engine ECU at the next shop visit of the ECU or engine, whichever occurs first, not to exceed five years after the effective date of this AD.

(h) Use paragraphs 3.A. through 3.B.(3)(f)4. of the Accomplishment Instructions of GE Service Bulletin No. CF6-80C2 S/B 73-0339, dated November 17, 2005, to do the installation.

Definitions

(i) For the purposes of this AD:

(1) Next shop visit of the engine ECU is when the ECU is removed from the engine for overhaul or for maintenance.

(2) Next shop visit of the engine is when the engine is removed from the airplane for maintenance in which a major engine flange is disassembled after the effective date of this AD. The following engine maintenance actions, either separately or in combination with each other, are not considered a next engine shop visit:

(i) Removal of the upper high pressure compressor (HPC) stator case solely for airfoil maintenance.

(ii) Module-level inspection of the HPC rotor 3-9 spool.

(iii) Replacement of stage 5 HPC variable stator vane bushings or lever arms.

(iv) Removal of the accessory gearbox.

(v) Replacement of the inlet gearbox Teflon seal.

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.

(k) Installation of later FAA-approved ECU software versions that follow version 8.2.Q1, are acceptable alternative methods of compliance to this AD.

Special Flight Permits

(l) Under 14 CFR part 39.23, special flight permits are prohibited.

Issued in Burlington, Massachusetts, on October 18, 2006.

Thomas A. Boudreau,

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