Airworthiness directives: CFE Co.,

[Federal Register: September 23, 1999 (Volume 64, Number 184)]

[Proposed Rules]

[Page 51484-51486]

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

[DOCID:fr23se99-27]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-69-AD]

RIN 2120-AA64

Airworthiness Directives; CFE Company Model CFE738-1-1B Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY: This notice revises an earlier proposed airworthiness directive (AD), applicable to CFE Company model CFE738-1-1B turbofan engines, that would have required a one-time dimensional inspection of the curvic coupling tooth profile of certain high pressure compressor (HPC) rotor

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components to check for machining mismatches in the curvic coupling in specific engines and, if necessary, replacement with serviceable parts. That proposal was prompted by reports of machining mismatches in certain HPC rotor components that may decrease the service life of these HPC parts. This action, based on subsequent material stress testing and analysis by CFE Company, revises the proposed rule by eliminating the dimensional inspection requirement and imposing new, reduced life limits for certain HPC rotor components in all engines. The actions specified by this proposed AD are intended to prevent failure of certain HPC rotor components, which could result in an uncontained engine failure and damage to the airplane.

DATES: Comments must be received by November 22, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 98-ANE-69-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may also be sent via the Internet using the following address: ``9-ane- adcomment@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 CFE Company, Data Distribution, M/S 64-03/2101-201, PO Box 52170, Phoenix, AZ 85072-2170; telephone (602) 365-2493, fax (602) 365-5577. 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: Keith Mead, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238- 7744, 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 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 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-69-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-69-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to CFE Company model CFE738-1-1B turbofan engines, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on December 14, 1998 (63 FR 68707). That NPRM would have required a one-time dimensional inspection of the curvic coupling tooth profile of certain high pressure compressor (HPC) rotor components installed on specific engines to check for machining mismatches in the curvic coupling, and, if necessary, replacement with serviceable parts. That NPRM was prompted by the determination that certain stage 4 and 5 blisks, impeller aft shafts, and impellers in specified engines may have machining mismatches in the curvic coupling tooth profiles. That condition, if not corrected, could result in failure of certain HPC rotor components, which could result in an uncontained engine failure and damage to the airplane.

Events Since Issuance of the NPRM

Since the issuance of that NPRM, additional material stress testing indicates that the machining mismatch does not reduce cyclic life, as previously predicted by analysis. Therefore, the requirement for dimensional inspection of the curvic coupling tooth profile of the stage 4 and 5 blisk, impeller, and impeller aft shaft to check for machining mismatch can be removed. However, the additional testing indicates that for certain 4th and 5th stage blisks and impeller aft shafts the cyclic lives, for reasons not yet fully understood, are below previously predicted cyclic lives, independent of the presence of curvic coupling machining mismatches. Therefore, this proposal would reduce the cyclic life limits on certain stage 4 and 5 blisks and the impeller aft shafts.

Proposed Actions

This AD would require removal from service of certain stage 4 and 5 blisks and impeller aft shafts prior to exceeding new, reduced cyclic life limits, and replacement with serviceable parts. No parts in service at this time are near the reduced cyclic life limits. The manufacturer anticipates that the reduced limits may be increased based upon further testing and analysis.

Since this change expands the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Economic Analysis

There are approximately 245 engines of the affected design in the worldwide fleet. The FAA estimates that 156 engines would be affected by this proposed AD, that it would take approximately 10 work hours per engine if performed at a scheduled inspection, and 450 work hours if not performed at a scheduled inspection (applicable for 2 engines only). The average labor rate is $60 per work hour. Required parts, on a pro-rated basis, would cost approximately $13,613 per engine. Based on these figures, the total cost impact of the proposed AD on US operators is estimated to be $2,159,665.

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

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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:

   CFE Company: Docket No. 98-ANE-69-AD.

   Applicability: CFE Company Model CFE738-1-1B turbofan engines, installed on but not limited to the Dassault Aviation Falcon 2000 series airplanes.

   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 failure of certain high pressure compressor (HPC) rotor components, which could result in an uncontained engine failure and damage to the airplane, accomplish the following:

   (a) Remove from service certain stage 4 and 5 blisks and impeller aft shafts prior to exceeding the new reduced cyclic life limits as follows, and replace with serviceable parts:

   Cyclic Life Limit Nomenclature

   Part No. (P/N)

   (cycles since new)

   Stage 4 and 5 Blisk................ 6079T74P07

   2,370 6079T74P08

   3,450 6079T74P09

   3,790 Impeller Aft Shaft................. 6079T80P04

   5,100 6079T80P05

   2,160 6079T80P06

   7,100 6079T80P07

   7,100

   (b) Except for the provisions of paragraph (c) of this AD, no parts, identified by P/N in paragraph (a) of this AD, may be installed that exceed the new life limits.

   (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 requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

   Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

   Issued in Burlington, Massachusetts, on September 16, 1999. Donald E. Plouffe, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

   [FR Doc. 99-24787Filed9-22-99; 8:45 am]

   BILLING CODE 4910-13-P