[Federal Register Volume 63, Number 174 (Wednesday, September 9, 1998)]
[Proposed Rules]
[Pages 48138-48140]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-24186]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 92-ANE-23]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT9D 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 (PW) JT9D 
series turbofan engines, that currently requires initial and repetitive 
inspections of the sixth stage low pressure turbine (LPT) inner 
airseal, and modification of the sixth stage LPT inner airseal to 
reduce the potential for two failure modes. This action would require 
additional repetitive borescope inspections for sixth stage LPT inner 
airseals found with cracks less than one inch in length. This proposal 
is prompted by the publication of a revision to a PW service bulletin 
that introduces the new borescope inspections. The actions specified by 
the proposed AD are intended to prevent an uncontained failure of the 
sixth stage LPT inner airseal, which can result in damage to the 
aircraft.

DATES: Comments must be received by November 9, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 92-ANE-23, 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 Regional 
Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Tara Goodman, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7130, fax (781) 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,

[[Page 48139]]

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 92-ANE-23.'' 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 Regional Counsel, 
Attention: Rules Docket No. 92-ANE-23, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    On July 7, 1994, the Federal Aviation Administration (FAA) issued 
airworthiness directive (AD) 94-10-09, Amendment 39-8916 (59 FR 36047, 
July 15, 1994), applicable to Pratt & Whitney (PW) JT9D series turbofan 
engines, to require initial and repetitive on-wing borescope or eddy 
current inspections (ECI) of the sixth stage low pressure turbine (LPT) 
inner airseal rear retaining wing, initial and repetitive on-wing ECI 
of the sixth stage LPT inner airseal knife edges, rework of the sixth 
stage inner airseal knife edges, which is a terminating action to the 
repetitive knife edge inspections, and rework of the sixth stage LPT 
inner airseal rear retaining wing. That action was prompted by reports 
of thermal mechanical interference inducing low cycle fatigue (LCF) 
cracks at two locations on the sixth stage LPT inner airseal, resulting 
in five uncontained failures. That condition, if not corrected, could 
result in an uncontained failure of the sixth stage LPT inner airseal, 
which can result in damage to the aircraft.
    Since the issuance of that AD, PW has issued Service Bulletin (SB) 
No. 5978, Revision 4, dated May 6, 1998, which introduces additional 
repetitive borescope inspections for sixth stage LPT inner airseals 
found with cracks less than one inch in length.
    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 94-10-09 to add, at intervals not to 
exceed 50 cycles in service (CIS) since last inspection, additional 
repetitive borescope inspections for sixth stage LPT inner airseals 
found with cracks less than one inch in length. Consistent with the 
timetable of the existing AD, this proposal would require rework of the 
sixth stage LPT inner airseal knife edge diameters and rear retaining 
wings prior to further flight.
    There are approximately 566 engines of the affected design in the 
worldwide fleet. The FAA estimates that 157 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 2.1 work hours per engine to accomplish the 
proposed additional inspection, 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 $19,782.
    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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-8916 (59 FR 
36047, July 15, 1994) and by adding a new airworthiness directive to 
read as follows:

Pratt & Whitney: Docket No. 92-ANE-23. Supersedes AD 94-10-09, 
Amendment 39-8916.

    Applicability: Pratt & Whitney (PW) Model JT9D-59A, -70A, -7Q, 
and -7Q3 turbofan engines, installed on but not limited to Boeing 
747 series, McDonnell Douglas DC-10 series, and Airbus A300 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 (e) 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 an uncontained failure of the sixth stage low 
pressure turbine (LPT) inner airseal, which can result in damage to 
the aircraft, accomplish the following:
    (a) Prior to further flight, rework the sixth stage LPT inner 
airseal knife edge diameters in accordance with the Accomplishment 
Instructions of PW Service Bulletin (SB) 5847, Revision 2, dated 
October 31, 1990.
    (b) Eddy current inspect (ECI) or borescope inspect sixth stage 
LPT inner airseal rear retaining wings for cracks, as follows:
    (1) For sixth stage LPT inner airseals identified by part number 
(P/N) in PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 
3, dated May 20, 1992, with greater than 500 cycles since new (CSN) 
on the effective date of this AD, accomplish an initial ECI or 
borescope inspection prior to accumulating more than 250 cycles in 
service (CIS) after the effective date of this AD, or 500 CIS since 
the last in-shop fluorescent penetrant inspection (FPI), whichever 
occurs later, in accordance with the Accomplishment Instructions of 
PW SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated 
May 20, 1992.
    (2) For sixth stage LPT inner airseals identified by P/N in PW 
SB No. 5978, Revision 4, dated May 6, 1998, or Revision 3, dated May 
20, 1992, with less than or equal to 500 CSN on the effective date 
of this AD, accomplish an initial ECI or borescope

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inspection prior to accumulating 750 CSN, or 500 CIS since the last 
in-shop FPI, whichever occurs later, in accordance with the 
Accomplishment Instructions of PW SB No. 5978, Revision 4, dated May 
6, 1998, or Revision 3, dated May 20, 1992.
    (3) For sixth stage LPT inner airseals that meet the continue in 
service criteria described in PW SB No. 5978, Revision 4, dated May 
6, 1998, thereafter, ECI or borescope inspect the sixth stage LPT 
inner airseal retaining wing for cracks at intervals specified in 
accordance with the Accomplishment Instructions of PW SB No. 5978, 
Revision 4, dated May 6, 1998.
    (4) Remove cracked sixth stage LPT inner airseals that do not 
meet the continue in service criteria described in PW SB No. 5978, 
Revision 4, dated May 6, 1998, and replace with a new, or 
serviceable sixth stage LPT inner airseal that has been reworked in 
accordance with paragraph (c) of this AD.
    (5) Thereafter, inspect initially, reinspect, and remove from 
service, if necessary, the replacement sixth stage LPT inner 
airseals in accordance with paragraphs (b)(1), (b)(2), (b)(3), and 
(b)(4) of this AD.
    (c) Prior to further flight, rework the sixth stage LPT inner 
airseal rear retaining wing in accordance with the Accomplishment 
Instructions of PW SB 5745, Revision 2, dated October 24, 1990.

    Note 2: Rework of the sixth stage LPT inner airseal rear 
retaining wing in accordance with paragraph (c) of this AD does not 
exempt sixth stage LPT inner airseals from initial and repetitive 
inspections in accordance with paragraphs (b)(1), (b)(2), (b)(3), 
and (b)(4) of this AD.

    (d) Installation of a new, improved 6th stage LPT inner airseal, 
in accordance with PW SB No. 6054, Revision 1, dated April 24, 1992, 
constitutes terminating action to the inspections and rework 
required by this AD.
    (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. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 3: 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 
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 1, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-24186 Filed 9-8-98; 8:45 am]
BILLING CODE 4910-13-U