[Federal Register Volume 59, Number 243 (Tuesday, December 20, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31181]


[[Page Unknown]]

[Federal Register: December 20, 1994]


                                                   VOL. 59, NO. 243

                                         Tuesday, December 20, 1994

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-ANE-37]

 

Airworthiness Directives; General Electric Company CF6 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to General Electric Company (GE) CF6-
45/-50 series turbofan engines. This proposal would require a reduction 
of the low cycle fatigue (LCF) retirement lives for certain high 
pressure turbine rotor (HPTR) stage 2 disks, and would provide a 
drawdown schedule for those affected parts with reduced LCF retirement 
lives. This proposal is prompted by the results of a refined life 
analysis performed by the manufacturer which revealed minimum 
calculated LCF lives significantly lower than published LCF retirement 
lives. The actions specified by the proposed AD are intended to prevent 
a LCF failure of the HPTR stage 2 disk, which could result in an 
uncontained engine failure and damage to the aircraft.

DATES: Comments must be received by February 21, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 94-ANE-37, 12 New England 
Executive Park, Burlington, MA 01803-5299. 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 Aircraft Engines, CF6 Distribution 
Clerk, Room 132, 111 Merchant Street, Cincinnati, OH 45246. This 
information may be examined at the FAA, New England Region, Office of 
the Assistant Chief Counsel, 12 New England Executive Park, Burlington, 
MA.

FOR FURTHER INFORMATION CONTACT: Robert J. Ganley, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7138; fax (617) 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 filed in 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 94-ANE-37.'' 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 Assistant Chief Counsel, 
Attention: Rules Docket No. 94-ANE-37, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    This proposed airworthiness directive (AD) is applicable to General 
Electric Company (GE) CF6-45/-50 series turbofan engines. A study 
performed by the manufacturer using updated life analyses for the high 
pressure turbine rotor (HPTR) stage 2 disk has revealed minimum 
calculated low cycle fatigue (LCF) lives which are significantly lower 
than published LCF retirement lives. This condition, if not corrected, 
could result in a LCF failure of the HPTR stage 2 disk, which could 
result in an uncontained engine failure and damage to the aircraft.
    The FAA has reviewed and approved the technical contents of GE CF6-
50 Service Bulletin (SB) No. 72-1069, dated September 12, 1994, that 
describes a reduction in the published LCF retirement lives for 
affected HPTR stage 2 disks, and an FAA-approved rework procedure for 
the affected disks to increase the FAA-approved LCF retirement life to 
8,750 or 9,700 cycles since new (CSN), depending on the CSN of the disk 
when the rework is performed.
    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 a reduction of the published LCF retirement 
lives for certain HPTR stage 2 disks, and would provide a drawdown 
schedule for those affected disks with reduced LCF retirement lives. If 
the FAA-approved rework is accomplished, the LCF retirement life may be 
increased to 8,750 or 9,700 cycles, depending on the CSN of the disk 
when the rework is performed. The actions would be required to be 
accomplished in accordance with the service bulletin described 
previously.
    The FAA estimates that 280 engines installed on aircraft of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 194 work hours per engine to accomplish the proposed 
actions, and that the average labor rate is $55 per work hour. Required 
parts would cost approximately $16,383 per engine. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $7,574,840.
    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.
    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. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

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

General Electric Company: Docket No. 94-ANE-37.

    Applicability: General Electric Company (GE) CF6-45/-50 series 
turbofan engines installed on but not limited to Airbus A300 series, 
Boeing 747 series, and McDonnell Douglas DC-10 series aircraft.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent a low cycle fatigue (LCF) failure of the high 
pressure turbine rotor (HPTR) stage 2 disk, which could result in an 
uncontained engine failure and damage to the aircraft, accomplish 
the following:
    (a) Remove from service HPTR stage 2 disks Part Numbers (P/N) 
1474M49P04, 1474M49P05, 1474M49P06, 9045M35P15, 9045M35P17, and 
9045M35P18, in accordance with the following:
    (1) For disks that have accumulated less than 3,500 cycles since 
new (CSN) on the effective date of this airworthiness directive 
(AD), remove disk from service prior to accumulating 7,080 CSN.
    (2) For disks that have accumulated 3,500 CSN or more, but less 
than 7,080 CSN on the effective date of this AD, remove disk from 
service prior to accumulating 7,080 CSN, or prior to accumulating 
3,100 cycles in service (CIS) after the effective date of this AD, 
whichever occurs later, but not to exceed 9,700 CSN.
    (3) For disks which have accumulated 7,080 CSN or more on the 
effective date of this AD, remove disk from service at the next 
piece-part exposure, but not to exceed 9,700 CSN.
    (b) Remove from service HPTR stage 2 disks P/N 9264M58P01, 
9264M58P02, and 9264M58P03 prior to accumulating 7,080 CSN.
    (c) This AD establishes the following new LCF retirement lives 
which will be published in Chapter 5 of the CF6-50 Engine Task 
Numbered Shop Manual, GEK 50481: 7,080 cycles for HPTR stage 2 disk 
P/N 1474M49P04, 1474M49P05, 1474M49P06, 9045M35P15, 9045M35P17, 
9045M35P18, 9264M58P01, 9264M58P02, and 9264M58P03.
    (d) GE CF6-50 Service Bulletin (SB) No. 72-1069, dated September 
12, 1994, describes an FAA-approved rework procedure for the 
affected disks. Accomplishment of this rework increases the FAA-
approved LCF retirement life to 8,750 or 9,700 cycles, depending on 
the CSN of the disk when the rework is performed.
    (e) 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. The 
request should be forwarded through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Engine Certification Office.

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

    (f) 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 December 14, 1994.
Kirk E. Gustafson,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 94-31181 Filed 12-19-94; 8:45 am]
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