Airworthiness directives: General Electric Co.,

[Federal Register: October 26, 1999 (Volume 64, Number 206)]

[Proposed Rules]

[Page 57608-57609]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr26oc99-27]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-79-AD]

RIN 2120-AA64

Airworthiness Directives; General Electric Company CF6-80C2 Series Turbofan 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 General Electric Company (GE) CF6- 80C2 series turbofan engines. This proposal would require removal from service of affected fan mid shafts prior to reaching a new, lower cyclic life limit, and replacement with serviceable parts. This proposal is prompted by recent component test data. The actions specified by the proposed AD are intended to prevent fan mid shaft failure, which could result in an uncontained engine failure and damage to the aircraft.

DATES: Comments must be received by December 27, 1999.

ADDRESSES: Submit comments to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-79-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ad-engineprop@faa.gov''. Comments sent via the Internet must contain the docket number in the subject line. Comments may be inspected at this location between 8:00 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays.

The service information referenced in the proposed rule may be obtained from General Electric Company via Lockheed Martin Technology Services, 10525 Chester Road, Suite C, Cincinnati, Ohio 45215, telephone (513) 672-8400, fax (513) 672-8422. This information may be examined at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: William S. Ricci, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7742, fax (781) 238-7199.

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 should identify the Rules Docket number and be submitted 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 notice may be changed in light of the comments received.

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 filedin the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 98-ANE-79-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, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-79-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

General Electric Company (GE), the manufacturer of CF6-80C2 series turbofan engines, recently conducted component tests and analysis of low pressure rotor shafts that resulted in the need to reduce the cyclic life limit of fan mid shafts, part number (P/Ns) 9326M74P04 and P/N 9326M74P05. The analysis revealed high stress in the fan mid shaft spline teeth, which results in reduced component cyclic life. This condition, if not corrected, could result in fan mid shaft failure, which could result in an uncontained engine failure and damage to the aircraft.

Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other engines of this same type design, the proposed AD would require removal from service of affected fan mid shafts prior to reaching a new, lower cyclic life limit, and replacement with serviceable parts.

Economic Analysis

There are approximately 1,796 engines of the affected design in the worldwide fleet. The FAA estimates that 230 engines installed on aircraft of US registry would be affected by this proposed AD and that required parts would cost approximately $90,085 per engine. Based on these figures, the total cost impact of the proposed AD on US operators is estimated to be $20,719,600.

Regulatory Impact

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order

[[Page 57609]]

12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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.

   Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

   General Electric Company: Docket No. 98-ANE-79-AD.

   Applicability: General Electric Company (GE) CF6-80C2 series turbofan engines, with fan mid shafts, part number (P/N) 9326M74P04 or P/N 9326M74P05, installed. These engines are installed on but not limited to Airbus Industrie A300 and A310 series, Boeing 747 and 767 series, and McDonnell Douglas MD-11 series aircraft.

   Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

   Compliance: Required as indicated, unless accomplished previously.

   To prevent fan mid shaft failure, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

   Removal From Service

   (a) Remove from service affected fan mid shafts and replace with a serviceable part, as follows:

   Note 2: GE CF6-80C2 Service Bulletin (SB) No. 72-958, dated December 10, 1998, contains information on this subject.

   (1) For fan mid shafts that have accumulated 9,000 or more cycles-since-new (CSN) on the effective date of this AD, remove from service within 3,500 cycles-in-service (CIS) after the effective date of this AD, or prior to accumulating 15,000 CSN, whichever occurs first.

   (2) For fan mid shafts that have accumulated 1,800 CSN or more, but less than 9,000 CSN on the effective date of this AD, remove from service within 5,000 CIS, or prior to accumulating to 12,500 CSN, whichever occurs first.

   (3) For fan mid shafts that have accumulated less than 1,800 CSN on the effective date of this AD, remove from service prior to accumulating 6,800 CSN.

   Note 3: GE CF6-80C2 SB 72-750, Revision 2, dated September 4, 1998, contains information on reworking fan mid shafts that results in changing the part number. After that rework, this AD would not apply to engines containing the reworked fan mid shaft.

   New Life Limits

   (b) Except for the provisions of paragraph (a) of this AD, no fan mid shafts, P/N 9326M74P04 or 9326M74P05, may remain in service beyond 6,800 CSN.

   Alternate Method of Compliance

   (c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office (ECO). Operators shall submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

   Note 4: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

   Ferry Flights

   (d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.

   Issued in Burlington, Massachusetts, on October 20, 1999. David A. Downey, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.

   [FR Doc. 99-27937Filed10-25-99; 8:45 am]

   BILLING CODE 4910-13-P