Federal Register / Vol. 63, No. 144 /Tuesday, July 28, 1998 / Proposed Rules 40213

(ii) The part has accumulated more than

100 cycles in service since the last piece-part

opportunity inspection, provided that the

part was not damaged or related to the cause

for its removal from the engine.’’

(b) Except as provided in paragraph (c) of

this AD, and notwithstanding contrary

provisions in section 43.16 of the Federal

Aviation Regulations (14 CFR 43.16), these

mandatory inspections shall be performed

only in accordance with Life Limits Section

of the manufacturer’s ICA.

(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 Engine Certification

Office. Operators shall submit their requests

through an appropriate FAA Principal

Maintenance Inspector (PMI), who may add

comments and then send it to the Engine

Certification Office.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this airworthiness directive,

if any, may be obtained from the Engine

Certification Office.

(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 airplane to

a location where the requirements of this AD

can be accomplished.

(e) The records of the mandatory

inspections required as a result of revising

the Life Limits Section of the ICA and the air

carrier’s continuous airworthiness

maintenance program as provided by

paragraph (a) of this AD shall be maintained

by FAA-certificated air carriers which have

an approved continuous airworthiness

maintenance program in accordance with the

record keeping system currently specified in

their manual required by sections 121.369 of

the Federal Aviation Regulations (14 CFR

121.369); or, in lieu of the record showing the

current status of each mandatory inspection

required by sections 121.380(a)(2)(vi) of the

Federal Aviation Regulations (14 CFR

121.380(a)(2)(vi)), certificated air carriers

may establish an approved alternate system

of record retention that provides a method for

preservation and retrieval of the maintenance

records that include the inspections resulting

from this AD, and include the policy and

procedures for implementing this alternate

method in the air carrier’s maintenance

manual required by sections 121.369(c) of the

Federal Aviation Regulations (14 CFR

121.369 (c)); however, the alternate system

must be accepted by the appropriate PMI and

require the maintenance records be

maintained either indefinitely or until the

work is repeated.

Note 3: These record keeping requirements

apply only to the records used to document

the mandatory inspections required as a

result of revising the Life Limits Section to

the ICA as provided in paragraph (a) of this

AD, and do not alter or amend the record

keeping requirements for any other AD or

regulatory requirement.

Issued in Burlington, Massachusetts, on

July 16, 1998.

Jay J. Pardee,

Manager, Engine and Propeller Directorate,

Aircraft Certification Service.

[FR Doc. 98–19627 Filed 7–27–98; 8:45 am]

BILLING CODE 4910–13–P

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98–ANE–41–AD]

RIN 2120–AA64

Airworthiness Directives; General

Electric Company CF6–6, CF6–45, and

CF6–50 Series Turbofan Engines

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of proposed rulemaking

(NPRM).

SUMMARY: This proposal would require

revisions to the Time Limits Section of

the manufacturer’s Instructions for

Continued Airworthiness (ICA) for

General Electric Company (GE) CF6–6,

CF6–45, and CF6–50 series turbofan

engines to include required enhanced

inspection of selected critical lifelimited parts at each piece-part

exposure. This proposal would also

require an air carrier’s approved

continuous airworthiness maintenance

program to incorporate these inspection

procedures. Air carriers with an

approved continuous airworthiness

maintenance program would be allowed

to either maintain the records showing

the current status of the inspections

using the record keeping system

specified in the air carrier’s

maintenance manual, or establish an

acceptable alternate method of record

keeping. This proposal is prompted by

an FAA study of in-service events

involving uncontained failures of

critical rotating engine parts which

indicated the need for improved

inspections. The improved inspections

are needed to identify those critical

rotating parts with conditions, that if

allowed to continue in service, could

result in uncontained failures. The

actions specified by this proposed AD

are intended to prevent critical lifelimited rotating engine part failure,

which could result in an uncontained

engine failure and damage to the

airplane.

DATES: Comments must be received by

October 26, 1998.

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–

41–AD, 12 New England Executive Park,

Burlington, MA 01803–5299. Comments

may also be sent via the Internet using

the following address: ‘‘9-adengineprop@faa.dot.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.

FOR FURTHER INFORMATION CONTACT:

Karen Curtis, Aerospace Engineer,

Engine Certification Office, FAA, Engine

and Propeller Directorate, 12 New

England Executive Park, Burlington, MA

01803–5299; telephone (781) 238–7192,

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 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 98–ANE–41–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–41–AD, 12 New

England Executive Park, Burlington, MA

01803–5299.
40214 Federal Register / Vol. 63, No. 144 /Tuesday, July 28, 1998 / Proposed Rules

Discussion

A recent FAA study analyzing 15

years of accident data for transport

category airplanes identified several

failure mode root causes that can result

in serious safety hazards to transport

category airplanes. This study identified

uncontained failure of critical lifelimited rotating engine parts as the

leading engine-related safety hazard to

airplanes. Uncontained engine failures

have resulted from undetected cracks in

rotating parts that initiated and

propagated to failure. Cracks can

originate from causes such as

unintended excessive stress from the

original design, or they may initiate

from stresses induced from material

flaws, handling damage, or damage from

machining operations. The failure of

rotating parts can present a significant

safety hazard to the airplanes by release

of high energy fragments that could

injure passengers or crew by penetration

of the cabin, damage flight control

surfaces, sever flammable fluid lines, or

otherwise compromise the

airworthiness of the airplane.

Accordingly, the FAA has developed

an intervention strategy to significantly

reduce uncontained engine failures.

This intervention strategy was

developed after consultation with

industry and will be used as a model for

future initiatives. This intervention

strategy is to conduct enhanced,

nondestructive inspections of critical

life limited rotating components which

could most likely result in a safety

hazard to the airplane in the event of a

disk fracture. The need for additional

rule making is also being considered by

the FAA. Future ADs may be issued

introducing additional intervention

strategies to further reduce or eliminate

uncontained engine failures.

Properly focused enhanced

inspections require identification of the

parts whose failures present a safety

hazard to the airplane, identifying the

most critical features to inspect on these

parts, and utilizing inspection

procedures and techniques that improve

crack detection. The FAA, with close

cooperation of the engine

manufacturers, has completed a detailed

analysis that identifies the safety

significant parts and features, and the

most appropriate inspection methods.

Critical life-limited high energy

rotating parts are currently subject to

some form of recommended crack

inspection when exposed during engine

maintenance or disassembly. As a result

of this AD, the inspections currently

recommended by the manufacturer will

become mandatory for those parts listed

in the compliance section. Furthermore,

the FAA intends that additional

mandatory enhanced inspections

resulting from this AD serve as an

adjunct to the existing inspections. The

FAA has determined that the enhanced

inspections will significantly improve

the probability of crack detection while

the parts are disassembled during

maintenance. All mandatory inspections

must be conducted in accordance with

detailed inspection procedures

prescribed in the manufacturer’s

maintenance manual.

Additionally, this AD allows for air

carriers operating under the provisions

of 14 CFR part 121 with an FAAapproved continuous airworthiness

maintenance program, and entities with

whom those air carriers make

arrangements to perform this

maintenance, to verify performance of

the enhanced inspections by retaining

the maintenance records that include

the inspections resulting from this AD,

provided that the records include the

date and signature of the person

performing the maintenance action.

These records must be retained with the

maintenance records of the part, engine

module, or engine until the task is

repeated. This will establish a method

of record preservation and retrieval

typical to those in existing continuous

airworthiness maintenance programs.

Instructions must be included in an air

carrier’s maintenance manual providing

procedures on how this record

preservation and retrieval system will

be implemented and integrated into the

air carrier’s record keeping system.

For engines or engine modules that

are approved for return to service by an

authorized FAA-certificated entity and

that are acquired by an operator after the

effective date of this AD, the mandatory

enhanced inspections need not be

accomplished until the next piece-part

opportunity. For example, there is no

need for an operator to disassemble to

piece-part level an engine or module

returned to service by an FAAcertificated facility simply because that

engine or module was previously

operated by an entity not required to

comply with this AD. Furthermore, the

FAA intends for operators to perform

the enhanced inspections of these parts

at the next piece-part opportunity

following the initial acquisition,

installation, and removal of the part

following the effective date of this AD.

For piece parts that have not been

approved for return to service prior to

the effective date of this AD, the FAA

does intend that the mandatory

enhanced inspections required by this

AD be performed before such parts are

approved for return to service. Piece

parts that have been approved for return

to service prior to the effective date of

this AD may be installed; however,

enhanced inspection will be required at

the next piece-part opportunity.

This proposal would require, within

the next 30 days after the effective date

of this AD, revisions to the Time Limits

Section of the manufacturer’s

Instructions for Continued

Airworthiness (ICA) for General Electric

Company CF6–6, CF6–45, and CF6–50

series turbofan engines, and, for air

carriers, the approved continuous

airworthiness maintenance program.

General Electric Company, the

manufacturer of CF6–6, CF6–45, and

CF6–50 series turbofan engines, used on

14 CFR part 25 airplanes has provided

the FAA with a detailed proposal that

identifies and prioritizes the critical lifelimited rotating engine parts with the

highest potential to hazard the airplane

in the event of failure, along with

instructions for enhanced, focused

inspection methods. The enhanced

inspections resulting from this AD will

be conducted at piece-part opportunity,

as defined below in the compliance

section, rather than specific time

inspection intervals.

There are approximately 2,500

engines of the affected design in the

worldwide fleet. The FAA estimates that

1,139 engines installed on airplanes of

U.S. registry would be affected by this

proposed AD, that it would take

approximately 5 work hours per engine

for the fan disk inspections and 8 work

hours for the high pressure turbine rotor

(HPTR) (stage 1 and 2) disk inspections.

The average labor rate is $60 per work

hour. Using average shop visit rates, 219

fan disks and 911 HPTR (stage 1 and 2)

disks are expected to be affected per

year. The cost impact of the proposed

AD on U.S. operators is estimated to be

$500,000 per year.

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
Federal Register / Vol. 63, No. 144 /Tuesday, July 28, 1998 / Proposed Rules 40215

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.

§ 39.13 [Amended]

2. Section 39.13 is amended by

adding the following new airworthiness

directive:

General Electric Company: Docket 98–ANE–

41–AD.

Applicability: General Electric Company

(GE) CF6–6, CF6–45, and CF6–50 series

turbofan engines, installed on but not limited

to Airbus A300 series, Boeing 747 series, and

McDonnell Douglas DC–10 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 critical life-limited rotating

engine part failure, which could result in an

uncontained engine failure and damage to

the airplane, accomplish the following:

(a) Within the next 30 days after the

effective date of this AD, revise the

manufacturer’s Time Limits Section of the

Instructions for Continued Airworthiness

(ICA), and for air carrier operations revise the

approved continuous airworthiness

maintenance program, by adding the

following:

‘‘MANDATORY INSPECTIONS

(1) Perform inspections of the following

parts at each piece-part opportunity in

accordance with the instructions provided in

the applicable manual provisions:

Part nomenclature Part number

(P/N) Inspect per engine manual chapter

For CF6–6, CF6–45, CF6–50 Engines:

Fan Rotor, Stage 1 Disk .................................................................................................. All ................. 72–21–03 (CF6–6: Inspection CF6–

45/50: Task 72–21–03–200–000).

High Pressure Turbine (HPT), Stage 1 Disk ................................................................... All ................. 72–53–03 (CF6–6: Inspection,

CF6–45/50: Task 72–53–03–

200–000).

HPT, Stage 2 Disk ........................................................................................................... All ................. 72–53–04 (CF6–6: Inspection,

CF6–45/50: Task 72–53–04–

200–000).

(2) For the purposes of these mandatory

inspections, piece-part opportunity means:

(i) The part is considered completely

disassembled when done in accordance with

the disassembly instructions in the engine

manufacturer’s Engine Manual; and

(ii) The part has accumulated more than

100 cycles in service since the last piece-part

opportunity inspection, provided that the

part was not damaged or related to the cause

for its removal from the engine.’’

(b) Except as provided in paragraph (c) of

this AD, and notwithstanding contrary

provisions in section 43.16 of the Federal

Aviation Regulations (14 CFR 43.16), these

mandatory inspections shall be performed

only in accordance with the Time Limits

Section of the manufacturer’s ICA.

(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 Engine Certification

Office. Operators shall submit their requests

through an appropriate FAA Principal

Maintenance Inspector (PMI), who may add

comments and then send it to the Engine

Certification Office.

Note 2: Information concerning the

existence of approved alternative methods of

compliance with this airworthiness directive,

if any, may be obtained from the Engine

Certification Office.

(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 airplane to

a location where the requirements of this AD

can be accomplished.

(e) The records of the mandatory

inspections required as a result of revising

the Time Limits Section of the ICA and the

air carrier’s continuous airworthiness

maintenance program as provided by

paragraph (a) of this AD shall be maintained

by FAA-certificated air carriers which have

an approved continuous airworthiness

maintenance program in accordance with the

record keeping system currently specified in

their manual required by sections 121.369 of

the Federal Aviation Regulations (14 CFR

121.369); or, in lieu of the record showing the

current status of each mandatory inspection

required by sections 121.380(a)(2)(vi) of the

Federal Aviation Regulations (14 CFR

121.380(a)(2)(vi)), certificated air carriers

may establish an approved alternate system

of record retention that provides a method for

preservation and retrieval of the maintenance

records that include the inspections resulting

from this AD, and include the policy and

procedures for implementing this alternate

method in the air carrier’s maintenance

manual required by sections 121.369 (c) of

the Federal Aviation Regulations (14 CFR

121.369 (c)); however, the alternate system

must be accepted by the appropriate PMI and

require the maintenance records be

maintained either indefinitely or until the

work is repeated.

Note 3: These record keeping requirements

apply only to the records used to document

the mandatory inspections required as a

result of revising the Time Limits Section of

the ICA as provided in paragraph (a) of this

AD, and do not alter or amend the record

keeping requirements for any other AD or

regulatory requirement.

Issued in Burlington, Massachusetts, on

July 16, 1998.

Jay J. Pardee,

Manager, Engine and Propeller Directorate,

Aircraft Certification Service.

[FR Doc. 98–19628 Filed 7–27–98; 8:45 am]

BILLING CODE 4910–13–P