Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-66-AD; Amendment 39-11121; AD 99-08-15]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

requires revisions to the Time Limits Section (TLS) of the

manufacturer's Engine Manuals (EMs) for Pratt & Whitney (PW) PW4000

series turbofan engines to include required enhanced inspection of

selected critical life-limited parts at each piece-part exposure. This

amendment will also require an air carrier's approved continuous

airworthiness maintenance program to incorporate these inspection

procedures. This amendment is prompted by a Federal Aviation

Administration (FAA) study of in-service events involving uncontained

failures of critical rotating engine parts that 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 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: Effective May 13, 1999.

ADDRESSES: The information contained in this AD 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: 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: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an airworthiness

directive (AD) that is applicable to Pratt & Whitney (PW) PW4000 series

turbofan engines was published in the Federal Register on November 5,

1998 (63 FR 5943). That action proposed to require within the next 30

days after the effective date of this AD, revisions to the Time Limits

Section (TLS) of the Engine Manuals, and, for air carriers, the

approved continuous airworthiness maintenance program. Pratt & Whitney,

the manufacturer of PW4000 series turbofan engines has provided the FAA

with a detailed proposal that identifies and prioritizes the critical

life-limited rotating engine parts with the highest potential to hazard

the airplane in the event of failure, along with instructions for

enhanced, focused inspection methods. These enhanced inspections will

be conducted at piece-part opportunity, as defined below in the

compliance section, rather than specific inspection intervals.

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 suggests three changes to the

final rule:

(a) The commenter states that paragraph (a)(2)(ii) is confusing as

to inspection requirements for damaged parts. The FAA disagrees.

Standardized language to define the piece-part condition, and thus

trigger focused inspection, is required for uniform application of

these new requirements for all operators. The language contained in

this NPRM was developed by a broad group of FAA and industry members.

Therefore, the piece-part definition will remain as written.

(b) The commenter also recommends that to clearly specify the level

to which the fan hub must be disassembled prior to FPI, each manual

section referenced for the required inspections should also clearly

state whether miscellaneous parts are to be removed. The FAA agrees.

There are two areas on the PW4000 disks that are not typically

disassembled, and after review, are not required to be disassembled to

meet the intent of the proposed inspection. One of these areas is the

tie-rod bolt holes, which may in some cases have repair bushings

installed. The removal of these bushings would likely introduce more

problems than they would solve, and a crack/failure in this region (at

the disk OD) would not result in uncontainment. The other area is the

spinner flange flared nuts. These are captive nuts and must be drilled/

machined to be removed. Again, their removal/replacement would likely

introduce more problems than would be solved, and crack/failure in this

region would also not result in uncontainment. The final rule will be

modified to clarify the required level of disassembly. This level of

assembly is P/N 1A9021--3 the piece-part level is 1A9001. Inspection at

either level will satisfy the requirements of this AD.

(c) The commenter also states that the FAA should urge the OEMs to

agree upon universal pre-cleaning and fluorescent penetrant inspection

procedures and to call them out in their service documents. The FAA

partially agrees. The agency recognizes the need for, and is currently

engaged in, several other initiatives that will provide standardized

guidance on FPI precleaning, and several other procedural aspects of

FPI inspection. The FAA will take future action once

[[Page 17948]]

standardized procedures are developed and industry consensus is

reached. Therefore, no changes will be made to this AD at this time.

Another commenter recommends four changes to this AD:

(a) The commenter believes that critical compliance data is

contained in the Discussion section of this AD, in the statement ``For

engines or engines modules that are approved for return to service. * *

*'' The FAA does not agree. The AD mandates changes to the OEM's manual

and Operators Continuous Airworthiness Program. The information

referenced by the commenter is background information, not critical

compliance data.

(b) The commenter also believes that paragraph (e) of the proposed

rule is unclear, and recommends that it be revised by eliminating the

word ``or'' from the first sentence, and beginning a second sentence

with ``In lieu of the record.* * *'' The FAA concurs in part.

Generally, record keeping requirements are addressed in other

regulations and this AD does not change those requirements. The FAA has

revised paragraph (e) of this AD with new language to clarify the

record keeping aspects of the new mandatory inspections.

(c) The commenter also suggests that disks be referred to by

utilizing the term ``All'' instead of identifying them by specific P/N.

The FAA partially agrees. Utilizing the reference ALL instead of

specific P/N's is preferable in some aspects; it eliminates the

possibility of underspecifying (omitting parts) that exists whenever

using specific P/N's. However, because P & W has initiated the proposed

manual changes and they are accurate, they will not be changed at this

time. In addition, future parts will be addressed via Intro into

Service documentation, rather than with further AD's. These inspections

will be built into the maintenance plan/documentation for new parts

from the beginning. AD's were meant to deal only with parts already in

service--new parts will incorporate these inspections from the

beginning in the manufacturers' documentation.

(d) The commenter also points out that ``Inspection 06'' referred

to in the NPRM does not exist in the present manual. ``Inspection 06''

is not included in the present manual edition. P & W has submitted this

change to their Tech Services group and it will appear in the next

manual revision.

No comments were received on the economic analysis contained in the

proposed rules. Based on that analysis, the FAA has determined that the

annual per engine cost of $156 does not create a significant economic

impact on small entities.

Additional editorial comments--Engine model PW2168A was omitted

from the proposed rule and has been added to the Applicability section

of this AD.

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 changes described

previously. The FAA has determined that these changes will neither

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

the AD.

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, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 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:

99-08-15 Pratt & Whitney: Amendment 39-11121. Docket 98-ANE-66-AD.

Applicability: Pratt & Whitney PW4050, PW4052, PW4056, PW4060,

PW4060A, PW4062, PW4060C, PW4152, PW4156, PW4156A, PW4158, PW4160,

PW4168, PW4168A, PW4460, PW4462, PW4164, PW4074, PW4074D, PW4077,

PW4077D, PW4084, PW4084D, and PW4090 series turbofan engines,

installed on but not limited to Airbus A300, A310, and A330 series,

Boeing 747, 767, 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 . 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 manufacturer's

Engine Manual, Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822,

51A751, and 51A345, as applicable, for Pratt & Whitney PW4050,

PW4052, PW4056, PW4060, PW4060A, PW4062, PW4060C, PW4152, PW4156,

PW4156A, PW4158, PW4160, PW4460, PW4462, PW4164, PW4168, PW4074,

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

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

PW4000 series Engine Cleaning, Inspection, and Repair (CIR) Manuals:

[[Page 17949]]

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Manual

Part Nomenclature P/N Section Inspection CIR Manual

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

Hub, LPC Assembly........................... 50B321 (50B301 Detail)........ 72-31-07 02 51A357

Hub, LPC Assembly........................... 51B321 (51B301 Detail)........ 72-31-07 02 51A357

Hub, LPC Assembly........................... 52B021 (52B001 Detail)........ 72-31-07 02 51A357

Hub, LPC Assembly........................... 51B631 (50B601 Detail)........ 72-31-07 02 51A750

Hub, LPC Assembly........................... 51B821 (51B801 Detail)........ 72-31-07 02 51A750

Hub, LPC Assembly........................... 52B521 (52B501 Detail)........ 72-31-07 02 51A750

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(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

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 applicable PW4000 series Engine Manuals.

(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) 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 Instructions for Continuous

Airworthiness (ICA) 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 engine manuals.

(f) This amendment becomes effective on May 13, 1999.

Issued in Burlington, Massachusetts, on April 2, 1999.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification

Service.

[FR Doc. 99-8865 Filed 4-12-99; 8:45 am]

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