Airworthiness Directives; Pratt & Whitney JT8D-200 Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket 98-ANE-43-AD; Amendment 39-11188; Ad 99-12-04]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney JT8D-200 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-200 series turbofan engines, that

requires revisions to the engine manufacturer's Time Limits Section

(TLS) of the JT8D-200 Turbofan Engine 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 part 39 of the Federal

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

directive (AD) that is applicable to Pratt & Whitney (PW) JT8D-200

series turbofan engines was published in the Federal Register on July

28, 1998 (63 FR 40216). 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 PW JT8D-200 Turbofan Engine Manual, and,

for air carriers, the approved continuous airworthiness maintenance

program. The manufacturer of JT8D-200 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.

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 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.

One commenter suggests 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 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, FAA

established the 100 cycle threshold. No consideration for crack growth

time was given in the choice of this number nor was time-since-new

(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

[[Page 30383]]

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 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 suggested that the parts requiring focused inspection

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 states that a ``spot focused'' fluorescent-penetrant

inspection (FPI) should be performed in the rivet area of the fan hub

instead of removing rivets, the air seal, and the compressor duct to

inspect the fan hub. The commenter believes that rivet removal and

replacement may induce stresses and cause cracks. The FAA does not

concur. Inspection of the entire fan hub (i.e., bore, all holes, fillet

radii, rim slot bottom, upper lug surface, pressure face of dovetail

slots) is needed to detect all possible crack indications. Although few

cracks have been detected thus far, there is concern that other high

stress areas (e.g. dovetail slots) may be affected. Furthermore,

removal of the assembled parts (air seal and compressor duct) will

provide assurance that liquids for inspection and cleaning will not

become entrapped in the titanium hub.

One commenter states that the phrase ``by or related to the cause

of its removal from the engine'' should be added for clarification to

paragraph (2)(b) of Inspection Requirements, paragraph A, in the

Compliance Section. The FAA concurs and the phrase has been added.

One commenter states that the affected assembly part number (P/N)

in the Compliance Section, paragraph B, Parts Requiring Inspection

Table, is in error and should be 5000421-01. The FAA concurs and the P/

N has been revised.

One commenter states that AD 97-17-04 compliance requirements

relative to the JT8D Engine Manual, P/N 773128, 72-33-31 Insp-02, 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. The inspection

requirements of AD 97-17-04 remain intact and are not affected by this

AD. While the inspection techniques are similar, this AD will require

inspections at every piece-part opportunity without having to remove

bushings. AD 97-17-04 requires inspections with bushings removed at

fixed inspection intervals depending on part serial number.

One commenter states that an existing alternative method of

compliance (AMOC) for removal of C1 hub bushings prior to eddy current

inspection should be allowed for this AD. The FAA does not concur.

Because this AD does not require the removal of bushings at every

piece-part opportunity, no AMOC for an alternate bushing removal

procedure is required.

One commenter states that the PW JT8D-200 Turbofan Engine Manual

section reference in the Parts Requiring Inspection table is in error

and should read 72-33-31. The FAA concurs and the table has been

revised.

No comments were received on the economic analysis contained in the

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

annual per engine cost of $240 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 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:

99-12-04 Pratt & Whitney: Amendment 39-11188. Docket 98-ANE-43-AD.

Applicability Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C,

and -219 series turbofan engines, installed on but not limited to

McDonnell Douglas MD80 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

[[Page 30384]]

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, alternation, 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 Limit Section (TLS) of the PW JT8D-200 Engine Manual

(EM), Part Number 773128, and for air carrier operations revise the

approved continuous airworthiness maintenance program, by adding the

following:

``3. 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 is not damaged or

related to the cause of its removal from the engine.

(3) The inspections specified in this section do not replace or

make unnecessary 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.

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

Description Section Inspection

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

Hub (Disk), 1st Stage Compressor:

5000501-01 (Hub detail).......... 72-33-31 -02,-03

5000421-01 (Hub assembly)........ 72-33-31 -02,-03''

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

(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 TLS of the PW JT8D-

200 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 issued in accordance with

Secs. 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.

(b) 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. 99-14447 Filed 6-7-99; 8:45 am]

BILLING CODE 4910-13-M