Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 91-ANE-45; Amendment 39-8862; AD 94-07-04]

Airworthiness Directives; General Electric Company CF6 Series

Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to General Electric Company (GE) CF6-80A series turbofan

engines, that requires an inspection for cracks in the stage 1 high

pressure turbine (HPT) disk rim bolt holes. This amendment is prompted

by a report of an uncontained stage 1 HPT disk failure, which resulted

in an aborted takeoff. The actions specified by this AD are intended to

prevent an uncontained stage 1 HPT disk failure, which could result in

an inflight engine shutdown, aborted takeoff, or damage to the

aircraft.

DATES: Effective May 23, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of May 23, 1994.

ADDRESSES: The service information referenced in this AD 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 Federal Aviation Administration

(FAA), New England Region, Office of the Assistant Chief Counsel, 12

New England Executive Park, Burlington, MA; or at the Office of the

Federal Register, 800 North Capitol Street NW., suite 700, Washington,

DC.

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: A proposal to amend part 39 of the Federal

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to General Electric Company (GE) CF6-80A series turbofan

engines was published as a notice of proposed rulemaking (NPRM) in the

Federal Register on January 9, 1992 (57 FR 857). That action proposed

to require a one-time inspection for cracks in the stage 1 high

pressure turbine (HPT) disk rim bolt holes in accordance with GE

Commercial Engine Service Memorandum (CESM) No. 27, dated September 27,

1991.

Since the issuance of that NPRM, GE issued CF6-80A Service Bulletin

(SB) No. 72-604, Revision 3, dated April 8, 1993, which revised the

inspection program based on additional investigation findings on the

reported disk failure. A Supplemental NPRM was published in the Federal

Register on November 3, 1993 (58 FR 58667), which proposed to require

an inspection for cracks in the stage 1 HPT disk rim bolt holes in

accordance with the revised inspection program described in GE CF6-80A

SB No. 72-604, Revision 3, dated April 8, 1993.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the rule as proposed.

One commenter states that previous revision levels of GE CF6-80A SB

No. 72-604, Revision 3, dated April 8, 1993, should be incorporated by

reference. The FAA does not concur. Compliance paragraph (d) of the

proposed rule already addresses inspections performed in accordance

with these previous revision levels.

One commenter states that the AD should not refer to a specific

revision of the GE SB, but instead, use the phrase ``latest revision''

when citing the SB. The FAA does not concur. When incorporating a

manufacturer's SB into an AD, the actual revision level and issue date

of the SB must be specified. The FAA can not review and approve the

technical contents of a document that has not yet been issued. Future

revisions to a SB incorporated into an AD that do not substantively

change the compliance requirements or times, may carry FAA approval as

alternate methods of compliance to allow operators the greatest

flexibility in performing the requirements of an AD.

One commenter states that the inspection thresholds should be based

on cycles since new on the issuance of GE CF6-80A SB No. 72-604,

Revision 2, dated July 2, 1992, rather than the effective date of the

AD to be consistent with their current inspection program. The FAA does

not concur. This recommendation might cause an undue burden to another

operator based on the anticipated publication date of this amendment.

The FAA has determined that the compliance end date of December 31,

1993, noted in compliance paragraph (a)(3) of the NPRM, is inconsistent

with the anticipated publication date of this amendment, and as such

may place undue burden on operators. The NPRM proposed a compliance

period of 60 days to accomplish the required actions based on the

anticipated publication date of the AD at the time the NPRM was

published. Therefore, the compliance end date in compliance paragraph

(a)(3) of this final rule has been revised to 90 days after date of

publication in the Federal Register. This time period is comprised of

the 30 day period after publication and prior to the effective date

plus 60 days.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the change described

previously. The FAA has determined that this change will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 154 GE CF6-80A series engines of the

affected design in the worldwide fleet. The FAA estimates that 48

engines installed on aircraft of U.S. registry will be affected by this

AD, that it will take approximately 232 work hours per engine to

accomplish the required actions, and that the average labor rate is $55

per work hour. Required parts will cost approximately $172,800 per

engine. Based on these figures, and assuming all inspected disks

require replacement, the total cost impact of the AD on U.S. operators

is estimated to be $8,906,880.

The regulations adopted herein will 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 final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 14 CFR part

39 of the Federal Aviation Regulations 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:

94-07-04 General Electric Company: Amendment 39-8862. Docket 91-ANE-

45.

Applicability: General Electric Company (GE) CF6-80A series

turbofan engines installed on but not limited to, Boeing 767 series

and Airbus A310 series aircraft.

Compliance: Required as indicated, unless accomplished

previously.

To prevent an uncontained stage 1 high pressure turbine (HPT)

disk failure, which could result in an inflight engine shutdown,

rejected takeoff, or damage to the aircraft, accomplish the

following:

(a) Eddy current inspect (ECI) for cracks stage 1 HPT disks,

Part Numbers (P/N) 9234M67G12, 9234M67G13, 9234M67G14, 9234M67G15,

9234M67G16, 9234M67G22, 9234M67G24, 9367M45G01, 9367M45G02,

9367M45G03, and 9367M45G04, regardless of serial number; and stage 1

HPT disks, P/N 9362M58G02, with serial numbers listed in paragraph

1.A. of GE CF6-80A Service Bulletin (SB) No. 72-604, Revision 3,

dated April 8, 1993; in accordance with the accomplishment

instructions of GE CF6-80A SB No. 72-604, Revision 3, dated April 8,

1993, as follows:

(1) For disks that have accumulated less than 3,000 cycles since

new (CSN) on the effective date of this AD, ECI the rim bolt holes

at the next engine shop visit after accumulating 3,000 CSN, but not

to exceed 4,500 CSN.

(2) For disks that have accumulated 3,000 CSN or more, but less

than 4,000 CSN on the effective date of this AD, ECI the rim bolt

holes at the next engine shop visit, but not to exceed 4,500 CSN.

(3) For disks that have accumulated 4,000 CSN or more, but less

than 9,500 CSN on the effective date of this AD, ECI the rim bolt

holes at the next engine shop visit, or prior to July 20, 1994,

whichever occurs earlier.

(4) For disks that have accumulated 9,500 CSN or more on the

effective date of this AD, ECI the rim bolt holes at the next engine

shop visit.

(b) ECI stage 1 HPT disks, P/N 9362M58G02, with serial numbers

not listed in paragraph 1.A. of GE CF6-80A SB No. 72-604, Revision

3, dated April 8, 1993, in accordance with the accomplishment

instructions of GE CF6-80A SB No. 72-604, Revision 3, dated April 8,

1993, at the next exposure of the stage 1 HPT disk at the piece part

level.

(c) Remove from service disks found cracked, and replace with

serviceable parts. Inspect replacement disks in accordance with

paragraph (a) or (b) of this AD, if applicable.

(d) Disks referenced in paragraph (a) or (b) of this AD that

have been inspected in accordance with Commercial Engine Service

Memorandum No. 27, dated September 27, 1991, or any revision level

of GE CF6-80A SB No. 72-604, prior to the effective date of this AD,

and whose CSN at the time of inspection was 3,000 or more, meet the

inspection requirements of paragraph (a) and (b) of this AD.

(e) For the purpose of this AD, an engine shop visit is defined

as the induction of an engine into a shop for maintenance involving

the separation of any major flange.

(f) An alternative method of compliance or adjustment of the

initial 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.

(g) Special flight permits may be issued in accordance with FAR

21.197 and 21.199 to operate the aircraft to a location where the

requirements of this AD can be accomplished.

(h) The inspection, and replacement, if necessary, shall be done

in accordance with the following service bulletin:

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Document No. Pages Revision Date

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GE CF6-80A SB No. 72-604 1 3 Apr. 8, 1993.

2 2 July 2, 1992.

3 3 Apr. 8, 1993.

4-12 2 July 2, 1992.

Total Pages: 12.....

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This incorporation by reference was approved by the Director of

the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR

part 51. Copies may be obtained from General Electric Aircraft

Engines, CF6 Distribution Clerk, room 132, 111 Merchant Street,

Cincinnati, OH 45246. Copies may be inspected at the FAA, New

England Region, Office of the Assistant Chief Counsel, 12 New

England Executive Park, Burlington, MA; or at the Office of the

Federal Register, 800 North Capitol Street NW., suite 700,

Washington, DC.

(i) This amendment becomes effective on May 23, 1994.

Issued in Burlington, Massachusetts, on March 23, 1994.

Marc Bouthillier,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-7785 Filed 4-20-94; 8:45 am]

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