Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-66-AD]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing

airworthiness directive (AD), applicable to Pratt & Whitney PW4000

series turbofan engines, that currently requires revisions to the Time

Limits Section of the manufacturer's Engine Manuals (EMs) to include

required enhanced inspection of selected critical life-limited parts at

each piece-part exposure. This action would add additional critical

life-limited parts for enhanced inspection. This proposal is prompted

by additional focused inspection procedures for other critical life-

limited rotating engine parts that have been developed by the

manufacturer. The actions specified by this proposed AD are intended to

prevent critical life-limited rotating engine part failure, which could

result in an uncontained engine failure and damage to the airplane.

DATES: Comments must be received by December 6, 1999.

ADDRESSES: Submit comments to the Federal Aviation Administration

(FAA), New England Region, Office of the Regional Counsel, Attention:

Rules Docket No. 98-ANE-66-AD, 12 New England Executive Park,

Burlington, MA 01803-5299. Comments may also be sent via the Internet

using the following address: ``[email protected]''. 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: Peter White, Aerospace Engineer,

Engine Certification Office, FAA, Engine and Propeller Directorate, 12

New England Executive Park, Burlington, MA 01803-5299; telephone (781)

238-7128, 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-66-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-66-AD, 12 New England Executive

Park, Burlington, MA 01803-5299.

Discussion

On April 2, 1999, the Federal Aviation Administration (FAA) issued

airworthiness directive (AD) 99-08-15, Amendment 39-311121 (64 FR

17947, April 13, 1999), to require revisions to the Time Limits Section

in the Engine Manuals (EMs) for certain Pratt & Whitney (PW) PW4000

series turbofan engines to include required enhanced inspection of

selected critical life-limited rotating components in the fan rotor at

each piece-part exposure.

New Procedures and Parts

Since the issuance of that AD, additional focused inspection

procedures for other critical life-limited rotating engine parts have

been developed. The new parts are the:

High Pressure Compressor (HPC) 5th stage disk

HPC front drum rotor

HPC rear drum rotor

HPC 15th stage disk

High Pressure Turbine (HPT) 1st stage airseal--on certain

models

HPT 2nd stage airsealuon certain models

HPT 1st stage (front) hub

HPT 2nd stage (rear) hub

Proposed Actions

Since an unsafe condition has been identified that is likely to

exist or develop on other products of this same type design, the

proposed AD would supersede AD 99-08-15 to require the additional

critical life-limited rotating engine parts to be subject to focused

inspection at each piece-part opportunity.

Changes From AD 99-08-15

The FAA has revised the piece-part definition to make it clearer at

which assembly level (assembly or detail) inspection of the part is

acceptable.

Also, the FAA has added additional part numbers (P/Ns) to the LPC

Hub Assembly section of the AD to include the PW4098 models. While the

inspections required for these parts were included in the

manufacturer's service documentation upon entry into service and

therefore do not need to be included in this AD, the FAA has included

these P/Ns to make this AD an all-inclusive inspection requirement for

all PW4000 series engine models.

Finally, the FAA has corrected an error in the LPC hub assembly,

which was discovered in the original AD. The detail P/N for the LPC hub

assembly

P/N 51B631 was changed from ``50B601'' to ``51B601.''

Economic Analysis

The FAA estimates that 450 engines installed on airplanes of US

registry would be affected by this proposed AD, that it would take

approximately 8 work hours per engine to accomplish the proposed

actions. The average labor rate is $60 per work hour, the average Shop

Visit Rate is .097, and the average usage is 3,250hrs/year/engine.

Based on these

[[Page 54583]]

figures and assuming that on average 5 components per visit will

require an inspection, the total cost impact of the proposed AD on US

operators is estimated to be $337,000 per year, or approximately $750

per engine per year.

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.

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 removing Amendment 39-11121 (64 FR

17947, April 13, 1999), and by adding a new airworthiness directive, to

read as follows:

Pratt & Whitney: Docket No. 98-ANE-66-AD. Supersedes AD 99-08-15,

Amendment 39-11121.

Applicability: Pratt & Whitney (PW) Model PW4050, PW4052,

PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A,

PW4158, PW4160, PW4460, PW4462, PW4168, PW4168A, PW4164, PW4074,

PW4074D, PW4077, PW4077D, PW4084, PW4084D, PW4090, PW4090D, and

PW4098 turbofan engines, installed on but not limited to Airbus

A300, A310, and A330 series, Boeing 747, 767, and 777 series, and

McDonnell Douglas MD-11 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:

Inspections

(a) Within the next 30 days after the effective date of this AD,

revise the Time Limits Section of the manufacturer's Engine Manual

(EM), Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822, 51A751,

and 51A345, as applicable, for PW Model PW4050, PW4052, PW4056,

PW4060, PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A, PW4158,

PW4160, PW4460, PW4462, PW4168, PW4168A, PW4164, PW4074, PW4074D,

PW4077, PW4077D, PW4084, PW4084D, PW4090, PW4090D, and PW4098

turbofan engines, 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 PW4000 series Engine Cleaning, Inspection, and Repair

(CIR) Manuals:

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CIR manual

Nomenclature (description) Part No. section CIR manual inspection CIR manual

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Hub, LPC Assembly.............. 50B221 (50B201 Detail); 72-31-07 Insp/Check-02......... 51A357

50B321 (50B301

Detail); 51B321

(51B301 Detail);

52B021 (52B001 Detail).

51B631 (51B601 Detail); 72-31-07 Insp/check-02......... 51A750

51B821 (51B801

Detail); 52B521

(52B501 Detail);

52B421 (52B401

Detail); 52B321

(52B101 Detail);

51B721 (52B101 Detail).

HPC 5th stage disk............. 51H005; 51H905; 54H405; 72-35-06 Insp/Check-02......... 51A357

54H705; 54H705-001;

56H605; 56H705.

54H705; 55H805; 56H505. 72-35-06 Insp/Check-02......... 51A750

HPC front drum rotor........... 50H859; 50H859-001; 72-35-07 Insp/Check-02......... 51A357

51H426-01; 52H559-01;

52H926-01; 53H676-01;

53H976-01; 54H626-01;

54H816-01; 55H106-01;.

53H406-01; 55H206-01; 72-35-07 Insp/Check-02......... 51A750

56H306-01.

HPC rear drum rotor............ 50H936; 50H936-002; 72-35-08 Insp/Check-02......... 51A357

53H923-01; 53H923-001.

53H973-01; 53H973-001; 72-35-10 Insp/Check-02......... 51A357

54H803-01; 54H803-001;

56H013-01.

55H722-01; 55H410-01; 72-35-10 Insp/Check-02......... 51A750

57H010-01; 57H210-01;

57H610-01.

HPC 15th disk.................. 55H615; 56H015; 57H715. 72-35-92 Insp/Check-02......... 51A750

HPT 1st stage airseal.......... 50L663; 50L959; 53L003. 72-52-19 Insp/Check-02......... 51A750

HPT first stage hub............ 50L501; 51L601; 51L201; 72-52-05 Insp/Check-02......... 51A357

52L401; 52L301 (51L901

Detail); 51L201-021

(51L201 Detail);

50L761 (52L201 Detail).

52L901 (53L001 Detail); 72-52-05 Insp/Check-02......... 51A750

52L701 (52L601

Detail); 53L121

(53L601 Detail);

53L021 (53L101 Detail).

[[Page 54584]]

HPT 2nd stage airseal.......... 50L926 (50L925 72-52-22 Insp/Check-02......... 51A750

Detail)*; 50L976

(50L925 Detail)*;

50L960 (50L961

Detail)*; 50L993

(50L994 Detail)*.

HPT second stage hub........... 50L602-021 (50L602 72-52-06 Insp/Check-02......... 51A357

Detail); 50L602-022

(50L602 Detail);

50L602-023 (50L602

Detail); 50L602-024

(50L602 Detail);

50L602-001; 50L902-021

(50L902 Detail);

50L902-022 (50L902

Detail); 52L002-021

(52L002 Detail);

52L402 (52L002

Detail); 52L802

(52L002 Detail);

53L602 (52L002 Detail).

52L702 (52L102 Detail); 72-52-06 Insp/Check-02......... 51A750

53L232 (53L202

Detail); 53L332

(53L402 Detail);

53L042 (53L702 Detail).

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* These parts must be inspected at the Detail level (metering plugs and Dampers must be removed). Assembly P/N

is listed only for reference and consistency with PW Manuals.

Except as noted, all parts may be inspected at any part number

level of disassembly listed in the Table above.

(2) For the purposes of these mandatory inspections, piece-part

opportunity means:

(i) The part is considered completely disassembled when

accomplished in accordance with the disassembly instructions in the

manufacturer's engine manuals to either the detail or assembly level

part numbers listed in the Table above (except as noted); 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 EMs.

Alternative 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 Engine Certification Office (ECO). Operators

shall submit their requests through an appropriate FAA Principal

Maintenance Inspector (PMI), who may add comments and then send it

to the 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.

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 airplane to a location where

the requirements of this AD can be accomplished.

Continuous Airworthiness Maintenance Program

(e) FAA-certificated air carriers that have an approved

continuous airworthiness maintenance program in accordance with the

record keeping requirement of Sec. 121.369(c) of the Federal

Aviation Regulations (14 CFR 121.369(c)) of this chapter must

maintain records of the mandatory inspections that result from

revising the Time Limits Section of the EMs and the air carrier's

continuous airworthiness program. Alternately, certificated air

carriers may establish an approved 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

Sec. 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. Records of the

piece-part inspections are not required under Sec. 121.380(a)(2)(vi)

of the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)). All

other operators must maintain the records of mandatory inspections

required by the applicable regulations governing their operations.

Note 3: The requirements of this AD have been met when the

engine manual changes are made and air carriers have modified their

continuous airworthiness maintenance plans to reflect the

requirements in the EMs.

Issued in Burlington, Massachusetts, on September 30, 1999.

David A. Downey,

Assistant Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 99-26136 Filed 10-6-99; 8:45 am]

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