Airworthiness Directives; Pratt & Whitney JT8D-1, -1A, -1B, -7, - 7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-48-AD; Amendment 39-11187; AD 99-12-03]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney JT8D-1, -1A, -1B, -7, -

7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Series

Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

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

applicable to Pratt & Whitney JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A,

-11, -15, -15A, -17, -17A, -17R, and -17AR series turbofan engines,

that requires revisions to the engine manufacturer's Time Limits

Section (TLS) of the JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15,

-15A, -17, -17A, -17R, and -17AR Turbofan Engines Manual to include

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 July 8, 1999.

FOR FURTHER INFORMATION CONTACT: Christopher Spinney, Aerospace

Engineer, Engine Certification Office, FAA, Engine and Propeller

Directorate, 12 New England Executive Park, Burlington, MA 01803-5299;

telephone (781) 238-7175, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: A proposal to amend pat 39 of the Federal

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

directive (AD) that is applicable to Pratt & Whitney (PW) PW JT8D-1, -

1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -

17AR series turbofan engines was published in the Federal Register on

July 28, 1998 (64 FR 40226). 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 JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -

9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Turbofan Engines Manual,

and, for air carriers, the approved continuous airworthiness

maintenance program. The manufacturer of JT8D series turbofan engines

has provided the Federal Aviation Administration (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. The enhanced inspections resulting from this AD

will be conducted at piece-part opportunity, as defined in this AD,

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 supports the measures outlined in the proposed rule.

Several commenters ask that the FAA clarify the record keeping

aspects of the mandatory inspections resulting from the required

changes to the Original Equipment Manufacturer's manual and operator's

continuous airworthiness maintenance program. Two commenters believe

that paragraph (e) of the proposed rule is unclear and suggests that

certain preamble language be added to it for clarity and that it be

revised by eliminating the word ``or'' from the first sentence and

beginning a second sentence with ``In lieu of the record. * * *'' Two

commenters state that the AD should be revised to clearly specify which

types of maintenance records must be retained (i.e., inspection

results, defect reporting requirements, date of performed maintenance,

signature of the person performing the maintenance). These commenters

believe that these revisions are necessary in order to avoid potential

differences in interpretation between the air carriers and the FAA.

And, one commenter states that the AD should clarify that there is no

need for a special form to comply with the AD record keeping

requirements. The FAA concurs in part. Generally, record keeping

requirements are addressed in other regulations and this AD does not

change those requirements. In order to allow flexibility from operator

to operator, the FAA does not concur that the AD itself specify the

precise nature of the records that will result from the required

changes to the manufacturer's manual and operator's maintenance

program. The FAA has, however, revised Paragraph (e) of this AD to

clarify record keeping aspects of the new mandatory inspections.

Several commenters suggested that the tables used to specify those

parts requiring mandatory inspections be given standardized formats and

that the parts be identified by ``all'' rather than by specific part

number. The FAA does not concur. The FAA intentionally allowed each

manufacturer to choose a format that fits their products manual.

Identification of parts requiring mandatory inspections has been

accomplished by either part number identification or use of the word

``all''. Part number identification was chosen by some manufacturers

since the processes and procedures needed to conduct new inspections

were not yet developed for all parts of a certain type, i.e., fan

disks/hubs. The FAA wants the manufacturers to have flexibility in

managing how their manuals are structured within Air Transport

Association code requirement.

One commenter requests that the FAA link the conduct of mandatory

inspections on whether the subject part was removed from an engine

while the engine was installed on the airplane or while the engine was

removed and in an overhaul shop. The commenter wishes to exempt those

parts that are removed

[[Page 30380]]

from installed engines from the focused inspections. The FAA does not

concur. The mandatory inspections are based on a single trigger. The

trigger is a part being completely disassembled using the engine manual

instructions (piece-part opportunity), and is not dependent on whether

an engine is installed on the airplane. This final rule mandates that

the definition of piece-part opportunity appears in the mandatory

section of each affected engine manual. This final rule further

mandates that an operator's continuous airworthiness maintenance

program be modified to capture those engine manual changes.

Several commenters suggest that the 100 cycle in service inspection

waiver provided in the piece-part opportunity definition was too low

and could not be justified from a crack growth standpoint or that

language be added to the requirements adding a minimum cycles in

service threshold after which mandatory inspections would be

applicable. The FAA does not concur. The 100 cycle waiver is intended

to allow short term alleviation from mandatory inspections for a part

recently inspected in accordance with the engine manual requirements.

It was specifically aimed at disassembled parts removed from an engine

following a test cell reject or some other occurrence that caused the

parts removal shortly after successful completion of mandatory

inspections. Waiver of mandatory inspections in this instance also

requires that the part was not damaged or related to the cause for its

removal from the engine. Mandatory inspections are also required on

fully disassembled parts regardless of time-since-new (TSN). The FAA is

aware that cracks can be missed during part inspections and that each

time a part is processed through an inspection line, the probability of

detecting a crack is increased. Commonly used on-condition maintenance

plans make it likely that a given part could be returned to service for

thousands of cycles without the need for additional focused inspection.

Recognizing two opposing aspects of part removal and inspection, i.e.,

a need for a brief exemption period following conduct of mandatory

inspections and the benefits of increased frequency of inspection, the

FAA established the 100 cycle threshold. No consideration for crack

growth time was given in the choice of this number nor was TSN

considered as a possible reason for exempting parts from focused

inspection. It is based strictly on keeping the frequency of mandatory

inspection as high as practical and therefore increasing the

probability of crack detection while providing a brief window of

exemption from mandatory inspection if certain conditions are met.

Therefore, the 100 cycle limit will remain in the compliance section of

the AD and no exemption will be allowed for low TSN parts.

One commenter states that the mandatory manual chapters were

modified to require new inspection requirements prior to issuance of

the final rule AD and that the FAA should provide written notification

to Flight Standards Offices that the inspections proposed in the

proposed rule are not mandatory until the establishment of an

effectivity date in a published final rule AD. Some confusion between

Operators, Manufacturers and Principal Maintenance Inspectors was

created when the mandatory manual sections were modified prior to the

release of a final rule AD. The FAA concurs in part. The manuals were

modified prior to issuance of the final rule to minimize implementation

delays from lengthy original equipment manufacturer EM revision cycles.

FAA will attempt a higher level of coordination of timing the manual

revisions so that the revisions follow final rule ADs in the future.

Such a notice, however, is beyond the scope of this AD and may well

cause additional confusion rather than clarify the present situation.

One commenter states that the proposed rule should be revised to

allow use of Foerster Defectometer eddy current instrument for Insp-02,

as it is currently approved for use in Insp-03. 72-33-31 Insp-02

currently only requires that a certain probe and sensitivity standard

be used to accomplish the inspection. The eddy current instrument to be

used for 72-33-31 Insp-02 is specified in the PW Standard Practices

manual, 70-37-02. The requirement for the Eddy Current signal

instrument is that it be equivalent in performance to a Foerster

Defectometer Model H 2.835. An eddy current signal instrument needs to

be deemed equivalent to the Defectometer Model H 2.835 in order to be

acceptable for 72-33-31 Insp-02. Therefore no changes are necessary to

the AD.

One commenter states that AD 95-10-10 compliance requirements

relative to the JT8D Engine Manual, P/N 481672, 72-33-31 Insp-03, as

specified in the proposed rule should be clarified. The FAA does not

concur that a change needs to be made to the AD, but offers the

following explanation for clarification purposes. AD 95-10-10 is

applicable to certain serial number fan hubs installed on JT8D engines.

While the inspections required are similar to this AD, 95-10-10 also

contains other overhaul requirements and very specific inspection

intervals. This AD is intended to inspect all JT8D first and second

stage compressor disks at every piece-part opportunity. The

requirements of both ADs must be met regardless of the overlapping

requirements.

One commenter states that ``XX'' in the inspection column of the

Table in the Compliance Section under paragraph B needs clarification.

The FAA concurs. At the time the proposed rule was published Insp-04

was not available. Chapter 5 of the Engine Manual was revised August 1,

1998, to include Insp-04. Inspection -XX has been changed to inspection

number -04 for first stage compressor disks.

One commenter states that stage 2 compressor disks in the Table

should be repositioned for clarity and Insp-02 should be included. The

FAA concurs. Inspection number -XX has been replaced with inspection

number -02 for second stage compressor disks.

One commenter states that the reference to Chapter 05-11-00 in Note

3 of the Compliance Section is incorrect. The FAA concurs. This final

rule has been revised to reference Chapter 05-10-00.

No comments were received on the economic analysis contained in the

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

annual per engine cost of $420 does not create a significant economic

impact on small entities.

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

[[Page 30381]]

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.

99-12-03 Pratt & Whitney: Amendment 39-11187, Docket 98-ANE-48-AD.

Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -

7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR series

turbofan engines, installed on but not limited to Boeing 727 and 737

series and McDonnell Douglas DC-9 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 Time Limits Section (TLS) of the Pratt & Whitney (PW)

JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A,

-17R, and -17AR Turbofan Engines Engine Manual (EM), part number

481672, and for air carrier operations revise the approved

continuous airworthiness maintenance program, by adding the

following:

``5. Critical Life Limited Part Inspection

A. Inspection Requirements:

(1) This section has the definitions for individual engine piece

parts and the inspection procedures which are necessary when these

parts are removed from the engine.

(2) It is necessary to do the inspection procedures of the piece

parts in paragraph B when:

(a) The part is removed from the engine and disassembled to the

level specified in paragraph B and

(b) The part has accumulated more than 100 cycles since the last

piece part inspection, provided that the part was not damaged or

related to the cause for its removal from the engine.

(3) The inspections specified in this paragraph do not replace

or make not necessary other recommended inspections for these parts

or other parts.

B. Parts Requiring Inspection

Note: Piece part is defined as any of the listed parts with all

the blades removed.

------------------------------------------------------------------------

Engine manual description Section Inspection

------------------------------------------------------------------------

Hub (Disk), 1st Stage Compressor:

491201......................... 72-33-31 -04,-02,-03

496501......................... 72-33-31 -04,-02,-03

504101......................... 72-33-31 -04,-02,-03

515201......................... 72-33-31 -04,-02,-03

594301......................... 72-33-31 -04,-02,-03

640501......................... 72-33-31 -04,-02,-03

640601......................... 72-33-31 -04,-02,-03

743301......................... 72-33-31 -04,-02,-03

749701......................... 72-33-31 -04,-02,-03

749801......................... 72-33-31 -04,-02,-03

750001......................... 72-33-31 -04,-02,-03

750101......................... 72-33-31 -04,-02,-03

778901......................... 72-33-31 -04,-02,-03

791401......................... 72-33-31 -04,-02,-03

791501......................... 72-33-31 -04,-02,-03

791601......................... 72-33-31 -04,-02,-03

791701......................... 72-33-31 -04,-02,-03

791801......................... 72-33-31 -04,-02,-03

806001......................... 72-33-31 -04,-02,-03

806101......................... 72-33-31 -04,-02,-03

817401......................... 72-33-31 -04,-02,-03

844401......................... 72-33-31 -04,-02,-03

845401......................... 72-33-31 -04,-02,-03

848001......................... 72-33-31 -04,-02,-03

848101......................... 72-33-31 -04,-02,-03

Disk, 2nd Stage Compressor:

482502......................... 72-33-33 -02

502502......................... 72-33-33 -02

520602......................... 72-33-33 -02

570302......................... 72-33-33 -02

570402......................... 72-33-33 -02

678202......................... 72-33-33 -02

730202......................... 72-33-33 -02

730302......................... 72-33-33 -02

730402......................... 72-33-33 -02

740502......................... 72-33-33 -02

745702......................... 72-33-33 -02

745902......................... 72-33-33 -02

746002......................... 72-33-33 -02

746802......................... 72-33-33 -02

760402......................... 72-33-33 -02

760502......................... 72-33-33 -02

807502......................... 72-33-33 -02

5002402-01..................... 72-33-33 -02

790832 (Disk assembly)......... 72-33-33 -02

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(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

in the EM.

(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 used in accordance with

Sec. 21.197 and Sec. 21.199 of the Federal Aviation Regulations (14

CFR 21.197 and 21.199) to operate the airplane to a location where

the requirement 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. Alternatively, 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 alternative 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

alternative 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

[[Page 30382]]

to reflect the requirements in the engine manuals.

(f) This amendment becomes effective on July 8, 1999.

Issued in Burlington, Massachusetts, on June 1, 1999.

Mark C. Fulmer,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 99-14446 Filed 6-7-99; 8:45 am]

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