[Federal Register Volume 64, Number 49 (Monday, March 15, 1999)]
[Proposed Rules]
[Pages 12770-12772]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-6214]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 92-ANE-15]
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 certain Pratt & Whitney
JT8D-200 series turbofan engines, that currently requires installation
of high pressure turbine (HPT) containment hardware. This action
proposes the removal of low pressure turbine (LPT)-to-exhaust case
bolts and nuts and replacement with improved LPT-to-exhaust case bolts
and nuts, and installation of improved HPT containment hardware. This
proposal is prompted by uncontained HPT events resulting from HPT shaft
fractures and LPT flange separations resulting from LPT blade failures.
The actions specified by the proposed AD are intended to prevent damage
to the aircraft resulting from uncontained engine debris following an
HPT shaft fracture or an LPT blade failure.
DATE: Comments must be received by May 14, 1999.
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-15, 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, Publications Department, Supervisor
Technical Publications Distribution, M/S 132-30, 400 Main St., East
Hartford, CT 06108; telephone (860) 565-7700, 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: James Rosa, Aerospace Engineer, Engine
Certification Office, FAA, Engine and Propeller Directorate, 12 New
England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-
7152, 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, 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-15.'' 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-15, 12 New England Executive Park,
Burlington, MA 01803-5299.
[[Page 12771]]
Discussion
On November 19, 1993, the Federal Aviation Administration (FAA)
issued airworthiness directive AD 93-23-10, Amendment 39-8746 (57 FR
57705, December 17, 1993), applicable to certain Pratt & Whitney JT8D-
200 series turbofan engines, to require installation of high pressure
turbine (HPT) containment hardware. That action was prompted by reports
of HPT shaft fractures, which caused uncontained HPT failures. That
condition, if not corrected, could result in damage to the aircraft
resulting from uncontained engine debris following an HPT shaft
fracture.
Since the issuance of that AD, the FAA has received reports of two
uncontained HPT events in PW JT8D-219 engines. Liberated blade debris
deflected off, and escaped forward of, the leading edge of the
containment hardware. These events were caused by HPT shaft fractures,
which resulted from oil fires in the No. 4/5 bearing compartment. Any
PW JT8D-209, -217, -217A, -217C and -219 engine produced prior to
issuance of Alert Service Bulletin (ASB) No. 6053 could have the
previous version of the containment shield installed in accordance with
AD 93-23-10; those engines produced after ASB 6053 was issued have
containment shields as shipped from Pratt & Whitney.
The FAA has also received reports of uncontained low pressure
turbine (LPT) failures caused by worn 3rd and 4th stage turbine shrouds
which resulted in fatigue cracking and subsequent LPT blade failures.
The impact of failed blades caused separation of the LPT and turbine
exhaust case flange allowing uncontained failures to occur. The FAA has
determined that only -217C and -219 models are in danger of uncontained
failures from HPT shaft fractures but all -209, -217, -217A, -217C and
-219 model engines are in danger of uncontained failures due to LPT
blade failures.
The FAA has reviewed and approved the technical contents of PW JT8D
Alert Service Bulletin (ASB) No. A6346, dated September 10, 1998, that
describes procedures for installing improved HPT containment hardware,
and PW Service Bulletin (SB) No. 6149, dated January 19, 1994, that
describes procedures for installation of improved LPT to turbine
exhaust case bolts and nuts.
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 93-23-10 to require, for PW Model JT8D-
217C and -219 engines, installation of improved HPT containment
hardware. This proposed AD would also require, for PW Model JT8D-209, -
217, -217A, -217C and -219 engines, installation of improved LPT to
turbine exhaust case bolts and nuts.
There are approximately 2,727 engines of the affected design in the
worldwide fleet. The FAA estimates that 1,473 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, and
that it would take no additional work hours per engine to accomplish
the proposed actions since they should take place when an engine is
already sufficiently disassembled for normal maintenance on those
parts. Required parts would cost approximately $19,911 per engine
(hardware supplied by Pratt & Whitney free of charge for engines with
current HPT containment hardware) for the 560 engines requiring
improved (over AD 93-23-10) containment hardware, and $3,275 for 1,473
engines requiring improved bolts and nuts. Based on these figures, the
total cost impact of the proposed AD on U.S. operators is estimated to
be $15,974,235. However, since Pratt and Whitney may provide HPT
containment hardware free of charge, the actual cost to operators may
be substantially reduced.
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 39-8746 (57 FR
57705, December 17, 1993) and by adding a new airworthiness directive
to read as follows:
Pratt & Whitney: Docket No. 92-ANE-15. Supersedes AD 93-23-10,
Amendment 39-8746.
Applicability: Pratt & Whitney (PW) Model JT8D-209, -217, -217A,
-217C, and -219 turbofan engines, 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 damage to the aircraft resulting from uncontained
engine debris following a high pressure turbine (HPT) shaft fracture
or a low pressure turbine (LPT) blade failure, accomplish the
following:
(a) For PW Model JT8D-217C and -219 engines, install improved
HPT containment hardware at the next shop visit after the effective
date of this AD but no later than December 31, 2004, in accordance
with PW JT8D Alert Service Bulletin (ASB) No. A6346, dated September
10, 1998.
(b) For PW Model JT8D-209, -217, -217A, -217C and -219 engines,
install improved LPT to turbine exhaust case bolts and nuts at the
next shop visit after the effective date of this AD but no later
than December 31, 2004, in accordance with paragraph 2.A.(1) and
2.B.(1) of PW Service Bulletin (SB) No. 6149, dated January 19,
1994.
(c) For the purpose of this AD, an engine shop visit is defined
as engine maintenance that entails the separation of the J and K
flanges.
[[Page 12772]]
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 aircraft to a location where the
requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on March 8, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 99-6214 Filed 3-12-99; 8:45 am]
BILLING CODE 4910-13-U