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

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 97-ANE-08]

RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney JT8D-200 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 JT8D-200

series turbofan engines, that currently requires for front compressor

front hubs (fan hubs), cleaning; initial and repetitive eddy current

(ECI) and fluorescent penetrant inspections (FPI) of tierod and

counterweight holes for cracks; removal of bushings; the cleaning and

ECI and FPI of bushed holes for cracks; and, if necessary, replacement

with serviceable parts. In addition, the current AD requires reporting

the findings of cracked fan hubs. This action will not change the

current AD's inspection procedures, or the effectivity date that starts

the cycle count for the initial inspection schedules. This AD will,

however, add an additional inspection schedule that requires the

initial inspection of certain fan hubs with standard drilled holes and

coolant channel drilled (CCD) holes to occur earlier than the existing

AD requires. This proposal is prompted by additional investigation

since publication of the current AD that reveals that certain fan hubs

with standard drilled holes and CCD holes may be more susceptible to

cracking. This proposal also requires reporting the results of the

initial fan hub inspections. The actions specified by the proposed AD

are intended to prevent fan hub failure due to tierod, counterweight,

or bushed hole cracking, which could result in an uncontained engine

failure and damage to the aircraft.

DATES: Comments must be received by April 25, 1997.

ADDRESSES: Submit comments in triplicate to the Federal

Aviation Administration (FAA), New England Region, Office of the

Assistant Chief Counsel, Attention: Rules Docket No. 97-ANE-08, 12 New

England Executive Park, Burlington, MA 01803--5299. Comments may also

be sent via the Internet using the following address: ``9-ad-

[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.

The service information referenced in the proposed rule may be

obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108;

telephone (860) 565-6600, fax (860) 565-4503. This information may be

examined at the FAA, New England Region, Office of the Assistant Chief

Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Diane Cook, Aerospace Engineer, Engine

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

England Executive Park, Burlington, MA 01803-

[[Page 8199]]

5299; telephone (617) 238-7134, fax (617) 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 97-ANE-08.'' 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 Assistant Chief Counsel,

Attention: Rules Docket No. 97-ANE-08, 12 New England Executive Park,

Burlington, MA 01803-5299.

Discussion

On January 13, 1997, the Federal Aviation Administration (FAA)

issued airworthiness directive AD 97-02-11, Amendment 39-9896 (62 FR

4902, February 3, 1997), applicable to Pratt & Whitney (PW) JT8D-200

series turbofan engines, to require cleaning, initial and repetitive

eddy current inspections (ECI) and fluorescent penetrant inspections

(FPI) for cracks of tierod and counterweight holes; removal of

bushings; the cleaning and initial and repetitive ECI and FPI of bushed

holes for cracks; and, if necessary, replacing with serviceable parts.

The compliance requirements allow selection of inspection schedules

depending on front compressor front hub (fan hub) Serial Numbers (S/Ns)

listed in PW Alert Service Bulletin (ASB) No. A6272, dated September

24, 1996, and includes an inspection schedule for those fan hubs whose

S/Ns are not listed in the ASB. In addition, the AD requires reporting

findings of cracked fan hubs. That action was prompted by a report of

an uncontained failure of a fan hub. That condition, if not corrected,

could result in fan hub failure due to tierod, counterweight, or bushed

hole cracking, which could result in an uncontained engine failure and

damage to the aircraft.

Since the issuance of that AD, the FAA has conducted additional

investigation of fan hub cracking and has determined it necessary to

include an additional inspection schedule for certain fan hubs with

standard drilled holes and coolant channel drilled (CCD) holes. The FAA

reviewed the manufacturing records of all fan hubs, a total of 253

which had notations related to the tierod or counterweight holes.

Notations are made in the manufacturing records if an event occurred

during manufacture of the hole such as a tool break, which can result

in work hardened material, which is more susceptible to cracking. Of

the 253 fan hubs with such notations, 113 were manufactured with a CCD

and the remaining 140 were manufactured with a standard drill. Although

CCD fan hubs are more prone to a work hardened layer, a standard drill,

under certain circumstances, may also cause a work hardened layer and

subsequent cracking.

The FAA has reviewed and approved the technical contents of PW ASB

No. A6272, dated September 24, 1996, that describes procedures for

cleaning and ECI and FPI of tierod and counterweight holes for cracks;

removal of bushings; and the cleaning, FPI, and ECI of bushed holes for

cracks. Even though the ASB contains three of the S/Ns of the fan hubs

that were removed from service in accordance with AD 96-15-06, the

manufacturer has informed the FAA that these fan hubs have been

destroyed during the investigation to confirm the failure mode.

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 97-02-11 to include an additional

inspection schedule for certain fan hubs with standard drilled holes

and CCD holes without changing inspection procedures, the existing

inspection schedules, or the current effectivity date of March 5, 1997.

There are approximately 2,624 engines of the affected design in the

worldwide fleet. The FAA estimates that 1,279 engines installed on

aircraft of U.S. registry would be affected by this proposed AD, that

it would take 20 work hours per engine for 360 engines to disassemble,

remove, inspect, and reassemble engines, and 4 work hours per engine

for 919 engines to inspect at piece-part exposure, and that the average

labor rate is $60 per work hour. Based on these figures, the total cost

impact of the proposed AD on U.S. operators is estimated to be

$862,560.

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 USC 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-9896 (62 FR

4902, February 3, 1997) and by adding

[[Page 8200]]

a new airworthiness directive to read as follows:

Pratt & Whitney: Docket No. 97-ANE-08. Supersedes AD 97-02-11,

Amendment 39-9896.

Applicability: Pratt & Whitney JT8D-209, -217, -217C, and -219

series turbofan engines with front compressor front hub (fan hub),

Part Number (P/N) 5000501-01, installed. These engines are installed

on but not limited to McDonnell Douglas MD-80 series aircraft.

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 fan hub failure due to tierod, counterweight, or

bushed hole cracking, which could result in an uncontained engine

failure and damage to the aircraft, accomplish the following:

(a) Inspect fan hubs for cracks in accordance with the

Accomplishment Instructions, Paragraph A, Part 1, and, if

applicable, Paragraph B, of PW ASB No. A6272, dated September 24,

1996, as follows:

(1) For fan hubs identified by Serial Numbers (S/Ns) in Table 2

of this AD, after the fan hub has accumulated more than 4,000 cycles

since new (CSN), as follows:

(i) Initially inspect within 790 cycles in service after March

5, 1997 (the effective date of AD 97-02-11), or 4,790 CSN, whichever

occurs later.

(ii) Thereafter, reinspect after accumulating 2,500 CIS since

last inspection, but not to exceed 10,000 CIS since last inspection.

(2) For fan hubs identified by S/Ns in Appendix A of PW ASB No.

A6272, dated September 24, 1996, after the fan hub has accumulated

more than 4,000 CSN, as follows:

(i) Select an initial inspection interval from Table 1 of this

AD, and inspect accordingly.

Table 1

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Initial inspection Reinspection

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1. Within 1,050 cycles in service (CIS) After accumulating 2,500

after the effective date of AD 97-02- CIS since last

11, March 5, 1997, or prior to inspection, but not to

accumulating 5,050 CSN, whichever exceed 6,000 CIS since

occurs later; last inspection.

or

2. Within 990 CIS after the effective After accumulating 2,500

date of AD 97-02-11, March 5, 1997, or CIS since last

prior to accumulating 4,990 CSN, inspection, but not to

whichever occurs later; exceed 8,000 CIS since

last inspection.

or

3. Within 965 CIS after the effective After accumulating 2,500

date of AD 97-02-11, March 5, 1997, or CIS since last

prior to accumulating 4,965 CSN, inspection, but not to

whichever occurs later. exceed 10,000 CIS since

last inspection.

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Table 2

[Hubs with traveler notations]

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Non CCD Non CCD Non CCD Non CCD

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M67663 M67802 P66880 S25545

M67671 M67812 P66885 S25558

M67675 M67826 R32732 S25564

M67681 M67829 R32733 S25598

M67685 M67830 R32735 S25618

M67686 M67831 R32740 S25621

M67687 M67832 R32741 S25637

M67697 M67834 R32810 S25640

M67700 M67843 R32849 T50693

M67706 M67849 R32850 T50752

M67710 M67858 S25222 T50785

M67712 M67866 S25464 T50791

M67713 M67868 S25481 T50792

M67714 M67869 S25483 T50819

M67715 M67872 S25484 T50823

M67716 M67888 S25486 T50827

M67717 N71771 S25488 T50874

M67722 N71804 S25489 T50875

M67723 N71806 S25490 T51058

M67725 N71810 S25491 T51104

M67726 N71811 S25492 R33186

M67730 N71875 S25494 S25528

M67731 N71876 S25495

M67746 N71921 S25497

M67751 N71965 S25498

M67753 N72062 S25499

M67764 N72126 S25500

M67765 N72152 S25501

M67784 N72162 S25502

M67791 N72207 S25505

M67792 N72216 S25506

M67793 N72219 S25507

M67794 N72242 S25508

M67795 P66693 S25509

M67796 P66695 S25514

M67797 P66696 S25529

M67798 P66698 S25532

M67799 P66699 S25541

M67800 P66737 S25543

M67801 P66753 S25544

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CCD Hub CCD Hub CCD Hub

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P66747 R33099 S25292

P66756 R33107 S25299

P66800 R33113 S25301

P66814 R33124 S25302

P66819 R33131 S25308

P66831 R33132 S25312

R32767 R33133 S25316

R32787 R33136 S25323

R32792 R33152 S25334

R32795 R33157 S25335

R32796 R33163 S25337

R32800 R33165 S25344

R32807 R33168 S25369

R32856 R33171 S25377

R32860 R33173 S25378

R32870 R33180 S25381

R32883 R33181 S25394

R32905 R33189 S25399

R32926 R33194 S25402

R32930 R33198 S25406

R32952 R33201 S25411

R32964 R33202 S25413

R32966 R33207 S25414

R32971 S25193 S25415

R32976 S25195 S25418

R32981 S25207 S25419

R32990 S25208 S25421

R32994 S25221 S25422

R33000 S25229 S25430

R33004 S25238 S25437

R33040 S25246 S25439

R33055 S25248 S25449

R33059 S25250

R33077 S25256

R33080 S25262

R33082 S25268

R33086 S25278

R33087 S25287

R33089 S25288

R33090

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(ii) Thereafter, reinspect at intervals that correspond to the

selected inspection interval.

(3) If a fan hub is identified in both Table 2 of this AD and

Appendix A of PW ASB No. A6272, dated September 24, 1996, inspect in

accordance with paragraph (a)(1) of this AD.

(4) For fan hubs with S/Ns not listed in Table 2 of this AD or

in Appendix A of PW ASB No. A6272, dated September 24, 1996, after

the fan hub has accumulated more than 4,000 CSN, inspect the next

time the fan hub is in the shop at piece-part level, but not to

exceed 10,000 CIS after March 5, 1997.

(5) Prior to further flight, remove from service fan hubs found

cracked or that exceed the bushed hole acceptance criteria described

[[Page 8201]]

in PW ASB No. A6272, dated September 24, 1996.

(b) Report the number of completed inspections on a monthly

basis and report findings of cracked fan hubs in accordance with

Accomplishment Instructions, Paragraph F, of Attachment 1 to PW ASB

No. A6272, dated September 24, 1996, within 48 hours after

inspection to Robert Guyotte, Manager, Engine Certification Branch,

Engine Certification Office, FAA, Engine and Propeller Directorate,

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

(617) 238-7142, fax (617) 238-7199; Internet:

Robert.G[email protected]. Reporting requirements have been

approved by the Office of Management and Budget and assigned OMB

control number 2120-0056.

(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 Manager, Engine Certification Office. The

request should be forwarded through an appropriate FAA Principal

Maintenance Inspector, who may add comments and then send it to the

Manager, 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 aircraft to a location where

the inspection requirements of this AD can be accomplished.

Issued in Burlington, Massachusetts, on February 14, 1997.

James C. Jones,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 97-4370 Filed 2-21-97; 8:45 am]

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