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

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 96-ANE-33]

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 adoption of a new airworthiness

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

turbofan engines. This proposal would require, 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, this proposal would require

reporting findings of cracked fan hubs. This proposal is prompted by a

report of an uncontained failure of a fan hub. 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 November 4, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), New England Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 96-ANE-33, 12 New England

Executive Park, Burlington, MA 01803-5299. 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: Robert E. 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.

[[Page 51848]]

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 96-ANE-33.'' 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. 96-ANE-33, 12 New England Executive Park,

Burlington, MA 01803-5299.

Discussion

The Federal Aviation Administration (FAA) received a report of an

uncontained failure of a front compressor front hub (fan hub), Part

Number 5000501-01, installed on a Pratt & Whitney (PW) JT8D-200 series

turbofan engine. The investigation revealed a localized work hardened

layer found in the tierod hole of the fan hub from which a crack

initiated and propagated to failure in low cycle fatigue. The FAA has

determined that the work hardened layer was the result of a coolant

channel drill using a single plunge drilling procedure during

manufacture. This condition, if not corrected, could result in fan hub

failure due to tierod or counterweight hole cracking, which could

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

The FAA has reviewed and approved the technical contents of PW

Alert Service Bulletin (ASB) No. A6272, dated September 24, 1996, that

describes procedures for cleaning and eddy current (ECI) and

fluorescent penetrant (FPI) inspection 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

serial numbers (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 require cleaning, initial and repetitive ECI and FPI

for cracks of tierod and counterweight holes; removing bushings;

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 fan

hub S/Ns listed in the ASB, and includes an inspection schedule for

those fan hubs whose S/Ns are not listed in the ASB. In addition, this

AD would require reporting findings of cracked fan hubs. The actions

would be required to be accomplished in accordance with the ASB

described previously.

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 approximately 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. 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 adding the following new

airworthiness directive:

Pratt & Whitney: Docket No. 96-ANE-33.

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

219 series turbofan engines, installed on but not limited to

McDonnell Douglas MD-80 series aircraft.

Note: 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 (d) 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 front compressor front hub (fan hub), Part Number

5000501-01, failure due to tierod, counterweight, or bushed hole

cracking, which could result in an

[[Page 51849]]

uncontained engine failure and damage to the aircraft, accomplish

the following:

(a) Fan hubs with fewer than 4,000 cycles since new (CSN) on the

effective date of this AD need not be inspected until accumulating

4,000 CSN. After the effective date of this AD, upon accumulating

4,000 CSN, perform the requirements of paragraph (b) of this AD.

(b) For fan hubs with 4,000 CSN, accomplish the following:

(1) For fan hubs identified by serial numbers (S/Ns) in Appendix

A of PW Alert Service Bulletin (ASB) No. A6272, dated September 24,

1996, inspect for cracks in accordance with the initial inspection

intervals of Table 1 of this AD, in accordance with the

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

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

1996.

(i) Fan hubs that have been initially inspected in accordance

with paragraph (b)(1) of this AD must be reinspected in accordance

with the reinspection requirements of the schedule selected for

initial inspection.

(ii) Reinspect for cracks in accordance with the reinspection

intervals of Table 1 of this AD in accordance with the

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

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

1996.

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 CIS

after the effective date of this AD, or since last inspection, but

prior to accumulating 5,050 CSN, not to exceed 6,000 CIS

whichever occurs later. since last inspection.

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

of this AD, or prior to accumulating since last inspection, but

4,990 CSN, whichever occurs later. not to exceed 8,000 CIS

since last inspection.

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

of this AD, or prior to accumulating since last inspection, but

4,965 CSN, whichever occurs later. not to exceed 10,000 CIS

since last inspection.

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(2) For fan hubs with S/Ns not listed in Appendix A of PW ASB

No. A6272, dated September 24, 1996, inspect at the next time the

fan hub is in the shop at piece-part level, but not to exceed 10,000

CIS after effective date of this AD in accordance with the

Accomplishment Instructions, Paragraph A, Part 2, and, if

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

1996.

(3) Remove from service fan hubs found cracked or exceed the

bushed hole acceptance criteria in accordance with PW ASB No. A6272,

dated September 24, 1996, and replace with serviceable parts.

(c) Report findings of cracked fan hubs 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.

(d) 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: Information concerning the existence of approved

alternative methods of compliance with this airworthiness directive,

if any, may be obtained from the Engine Certification Office.

(e) 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 requirements of this AD can be accomplished.

Issued in Burlington, Massachusetts, on September 27, 1996.

James C. Jones,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 96-25596 Filed 10-3-96; 8:45 am]

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