Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 81-ANE-03]

Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan

Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of

comment period.

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SUMMARY: This notice revises an earlier proposed airworthiness

directive (AD), applicable to Pratt & Whitney JT8D series turbofan

engines, that would have amended an existing AD by eliminating an

optional on-wing ultrasonic inspection of the 10th stage high pressure

compressor (HPC) disk, and by including an engine model inadvertently

omitted. That proposal was prompted by a report of an uncontained

failure of a 10th stage HPC disk that was previously inspected using

the on-wing ultrasonic inspection method. This action revises the

proposed rule by removing the reference to the inadvertently omitted

engine model, as the FAA has remedied this discrepancy in an earlier

correction to the AD, and changing the proposed action from amending AD

81-08-02 R2 to superseding that AD. The actions specified by this

proposed AD are intended to prevent uncontained fractures of 9th

through 12th stage HPC disks and engine failure.

DATES: Comments must be received by February 17, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration, New England Region, Office of the Assistant Chief

Counsel, Attention: Rules Docket No. 81-ANE-03, 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, Technical Publications Department, M/S

132-30, 400 Main Street, East Hartford, Connecticut, 06108. This

information may be examined at the FAA, New England Region, Office of

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

FOR FURTHER INFORMATION CONTACT: Mark A. Rumizen, Aerospace Engineer

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

New England Executive Park, Burlington, MA 01803-5299; telephone (617)

238-7137; 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 81-ANE-03.'' 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. 81-ANE-03, 12 New England Executive Park,

Burlington, MA 01803-5299.

Discussion

On February 7, 1984, the Federal Aviation Administration (FAA)

issued airworthiness directive (AD) 81-08-02 R2, Amendment No. 39-4817

(49 FR 7361; February 29, 1984), to require initial and repetitive

inspections of 9th through 12th stage high pressure compressor (HPC)

disks at the tierod holes in Pratt & Whitney (PW) JT8D series turbofan

engines. That action was prompted by cracks in the tierod holes in HPC

disks that resulted in engine failures. That condition, if not

corrected, can result in uncontained fractures of 9th through 12th

stage HPC disks and engine failure.

On August 30, 1984, the FAA issued a correction to AD 81-08-02 R2,

Amendment 39-4817 (49 FR 35618; September 11, 1984), to include an

engine model that had been inadvertently omitted from the AD.

Since issuance of AD 81-08-02 R2, the FAA received a report of an

uncontained fracture of a 10th stage HPC disk. This disk had been

subjected to three previous on-wing ultrasonic inspections prior to

fracture. This method has since been determined as inadequate for

detecting tierod hole cracking.

On May 8, 1989, the FAA issued an NPRM that was published in the

Federal Register (54 FR 22306; May 23, 1989), that would have amended

the existing AD by eliminating the optional on-wing ultrasonic

inspection of the 10th stage HPC disk, and by including an engine model

inadvertently omitted.

Since the issuance of that NPRM, the FAA has determined that the

reference to the inadvertently omitted engine model was unnecessary, as

the FAA had remedied this discrepancy in the August 30, 1984,

correction. Also, the FAA now utilizes a revised format that supersedes

existing AD's by publishing a complete document rather than only

amending applicable paragraphs of the compliance section. This

document, therefore, reprints the corrected AD compliance section text

in its entirety for clarity.

Since the FAA has changed the format of the proposed rule, the FAA

has determined that it is desirable to reopen the comment period to

provide additional opportunity for public comment.

There are approximately 200 engines which would be affected by this

AD, and the FAA has determined that eliminating the optional on-wing

ultrasonic inspection would have negligible economic impact, since most

operators use uninstalled tenth stage disk inspections.

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 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

Pratt & Whitney: Docket No. 81-ANE-03.

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

9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines

installed on but not limited to Boeing 727 series and 737 series,

and McDonnell Douglas DC-9 series aircraft.

Compliance: Required as indicated, unless accomplished

previously in accordance with PW Alert Service Bulletin (ASB) No.

4723, Revision 9, dated July 13, 1983; Revision 10, dated September

15, 1986; or Revision 11, dated October 30, 1987. All inspections

subsequent to the effective date of this airworthiness directive

(AD) must be accomplished in accordance with the methods and

intervals identified in PW ASB No. 4723, Revision 12, dated March 8,

1990, except as is specified in paragraph (d) of this AD.

To prevent uncontained fractures of 9th through 12th stage high

pressure compressor (HPC) disks and engine failure, accomplish the

following:

(a) Initially inspect 9th through 12th stage HPC disks at the

tierod holes in accordance with PW ASB No. 4273, Revision 12, dated

March 8, 1990.

(b) Thereafter, inspect 9th through 12th stage HPC disks at the

tierod holes in accordance with Tables I through V and Table VIII of

PW ASB No. 4723, Revision 12, dated March 8, 1990. Disks initially

inspected prior to the first inspection limit must be reinspected

before reaching the specified reinspection interval, or before

reaching the first inspection limit, whichever is later. In no case

shall the established life limits of the disks be exceeded.

(c) Remove cracked disks from service prior to further flight,

and replace with a serviceable part. Disks may be returned to

service if repaired in accordance with Paragraph 7 of PW ASB No.

4723, Revision 12, dated March 8, 1990.

(d) For 10th stage HPC disks that were last inspected in

accordance with the on-wing ultrasonic inspection procedure

specified in AD 81-08-02 R2 prior to the effective date of this AD,

inspect as follows:

(1) Perform a magnetic particle inspection or eddy current

inspection in accordance with the procedure defined in Paragraph 6

and Appendix B of PW ASB No. 4723, Revision 12, dated March 8, 1990,

no later than 750 cycles in service (CIS) since the last on-wing

inspection.

(2) Accomplish all subsequent inspections in accordance with the

methods and intervals specified in PW ASB No. 4723, Revision 12,

dated March 8, 1990.

(e) 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.

(f) 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 aircraft to a location where the

requirements of this AD can be accomplished.

Issued in Burlington, Massachusetts, on December 9, 1994.

James C. Jones,

Acting Manager, Engine and Propeller Directorate, Aircraft

Certification Service.

[FR Doc. 94-31061 Filed 12-16-94; 8:45 am]

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