Airworthiness Directives; Boeing Model 747-400 and 767 Series Airplanes Equipped With General Electric CF6-80C2 Series Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-400 and 767 series airplanes. This proposal would require modification of the core cowl assemblies of the engines. This action is necessary to prevent failure of the core cowl latches during an engine fire, and consequent in-flight separation of an engine core cowl and its strut fire barrier from the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by January 19, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-275-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-275-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2686; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-275-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-275-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA received a report indicating an in-flight engine fire occurred on a Model 747-400 series airplane powered by General Electric CF6-80C2 series engines. The fire was caused by a fuel leak in the Integrated Drive Generator fuel/oil heat exchanger and was ignited by fuel vapors coming in contact with the hot turbine case. The fire was located directly under the core cowls and caused significant damage to the cowls, which weakened the aluminum structure supporting the steel latches that hold the core cowls closed. Opening of the core cowls during an engine fire breaches the engine fire containment design features and could allow the engine fire to spread to the strut and wing. (Model 767 series airplanes powered by General Electric CF6-80C2 series engines have a similar design.) Such conditions, if not corrected, could result in separation of an engine core cowl and its strut fire barrier from the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletins 747-71-2285 (for Model 747-400 series airplanes) and 767-71-0088 (for Model 767 series airplanes), both dated October 8, 1998, which describe procedures for modification of the left- and right-hand core cowl assemblies of the engines. The modification includes, but is not limited to, replacement of the aluminum forward and extension frames located between the forward hinge and the latch in each core cowl with inconel frames that provide fireproof reinforcement to the core cowl latches. The Boeing service bulletins reference ROHR Service Bulletin TBC/80C2-NAC-71-028, dated August 1, 1998, as an additional source of service information for accomplishment of the modification. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletins described previously, except as discussed below.

Difference Between Service Bulletins and This Proposed AD

Operators should note that this proposed AD would require modification of the core cowl assemblies of the engines to be accomplished within 24 months after the effective date of this AD. The service bulletins recommend that this modification should be accomplished “as soon as manpower and facilities are available.” But in developing an appropriate compliance time for the proposed modification, the FAA considered not only the manufacturer's recommendation and the degree of urgency associated with addressing the subject unsafe condition, but also the average utilization of the affected fleet and the time necessary to perform the modification. The FAA has determined that 24 months represents an appropriate interval of time allowable wherein the modification can be accomplished during scheduled airplane maintenance and an ample number of required parts will be available for modification of the U.S. fleet within the proposed compliance period. The FAA also finds that such a compliance time will not adversely affect the safety of the affected airplanes.

Cost Impact

There are approximately 563 airplanes of the affected design in the worldwide fleet.

The FAA estimates that 14 Model 747-400 series airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 168 work hours (42 per engine) per airplane to accomplish the proposed modification, and that the average labor rate is $60 per work hour. Required parts would cost approximately $84,732 ($21,183 per engine) per airplane. Based on these figures, the cost impact of the modification proposed by this AD on U.S. operators is estimated to be $1,327,368, or $94,812 per airplane.

The FAA estimates that 64 Model 767 series airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 84 work hours (42 per engine) per airplane to accomplish the proposed modification, and that the average labor rate is $60 per work hour. Required parts would cost approximately $42,366 ($21,183 per engine) per airplane. Based on these figures, the cost impact of the modification proposed by this AD on U.S. operators is estimated to be $3,033,984 or $47,406 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this 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) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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.