[Federal Register Volume 63, Number 45 (Monday, March 9, 1998)]
[Proposed Rules]
[Pages 11381-11382]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-5797]
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Proposed Rules
Federal Register
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This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 63, No. 45 / Monday, March 9, 1998 / Proposed
Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-ANE-55-AD]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney PW4000 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 certain Pratt & Whitney PW4000
series turbofan engines. This proposal would reduce life limits of
certain 4th stage low pressure turbine (LPT) disks. It would also allow
the original life limits of the disks to be restored if reoperation is
performed to incorporate the original slotted cooling hole
configuration. This proposal is prompted by reports that a change of a
cooling hole geometry, which was introduced in the design of certain
4th stage LPT disks, inadvertently caused a reduction on the cooling
air flow to the disk and an increased level of stress. The actions
specified by the proposed AD are intended to prevent an uncontained
disk failure and damage to the aircraft.
DATES: Comments must be received by May 8, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 97-ANE-55-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``engineprop@faa.dot.gov''. 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. 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: Chris Gavriel, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7147, 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 97-ANE-55-AD.'' 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. 97-ANE-55-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration received a report that a change
was introduced in the design of certain 4th stage low pressure turbine
(LPT) disks, installed on Pratt & Whitney Model PW4056, PW4152,
PW4156A, PW4164, PW4168, and PW4460 turbofan engines, that
inadvertently caused the reduction of amount of cooling air flow to the
disk and resulted in a reduction of their life limits. These disks,
part number (P/N) 50N924, are identified by serial number (S/N) in this
AD. This condition, if not corrected, could result in an uncontained
disk failure and damage to the aircraft.
The FAA has reviewed and approved the technical contents of Pratt &
Whitney (PW) Service Bulletins (SB) No. PW4G 100-72-105, dated November
12, 1997, and SB No. PW4ENG 72-657, dated November 25, 1997, that
describe the reduced life limits for affected disks, and describe
procedures for reoperation of the disks to incorporate the slotted
cooling air configuration to restore their original life limits.
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 reduce life limits of affected 4th stage LPT disks,
identified by S/N. It would also allow the original life limits to be
restored, if reoperation is performed to incorporate the slotted
cooling air configuration. The actions would be required to be
accomplished in accordance with the SBs described previously.
There are approximately 27 engines of the affected design in the
worldwide fleet. The FAA estimates that there are currently no engines
installed on aircraft of U.S. registry would be affected by this
proposed AD, but if one were installed, it would take approximately 4
work hours per engine to accomplish the proposed actions, and that the
average labor rate is $60 per work hour. Required parts would cost
[[Page 11382]]
approximately $240 per engine. Based on these figures, the total cost
impact of the proposed AD per engine is estimated to be $480.
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 adding the following new
airworthiness directive:
Pratt & Whitney: Docket No. 97-ANE-55-AD.
Applicability: Pratt & Whitney Model PW4056, PW4152, W4156A,
PW4164, PW4168, and PW4460 turbofan engines, with 4th stage low
pressure turbine (LPT) disks, part number (P/N) 50N924, serial
numbers (S/Ns) CLDL BX2061, CLDL BX6620, CLDL BX2054, CLDL BX2055,
CLDL BX6596, CLDL BX2059, CLDL BX2060, CLDL BX6600, CLDL BX6597,
CLDL BX6599, CLDL BX6601, CLDL BX6598, CLDL BX6604, CLDL BX6605,
CLDL BX6602, CLDL BX6609, CLDL BX6607, CLDL BX6612, CLDL BX6611,
CLDL BX6610, CLDL BX6608, CLDL BX6606, CLDL BX6615, CLDL BX6616,
CLDL BX6619, CLDL BX2058, and CLDL BX6603 installed. These engines
are installed on but not limited to Airbus A330, Boeing 747, and
McDonnell Douglas MD-11 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 an uncontained disk failure and damage to the
aircraft, accomplish the following:
(a) Except as provided in paragraph (b) of this AD, prior to
accumulating 7,500 cycles in service (CIS), remove the affected 4th
stage LPT disks and replace them with new or serviceable parts.
Note 2: A list of the affected 4th stage LPT disks, identified
by P/N and S/N, appears in the ``Applicability'' paragraph for this
AD.
(b) Restoration of the original life limits on the affected
disks may be accomplished as follows:
(1) Reoperation performed on the LPT disks installed in PW4164
and PW4168 model engines, in accordance with Pratt & Whitney (PW)
Service Bulletin (SB) No. PW4G 100-72-105, dated November 12, 1997,
prior to 7,000 CIS to incorporate the slotted cooling air
configuration may restore the life limit to 15,000 CIS.
(2) Reoperation performed on the LPT disks installed in PW4156A
and PW4460 model engines in accordance with PW SB No. PW4ENG 72-657,
dated November 25, 1997, prior to 5,500 CIS to incorporate the
slotted cooling air configuration may restore the life limit to
15,000 CIS.
(3) Reoperation performed on the LPT disks installed in PW4056
and PW4152 model engines in accordance with PW SB No. PW4ENG 72-657,
dated November 25, 1997, prior to 4,500 CIS to incorporate the
slotted cooling air configuration may restore the life limit to
20,000 CIS.
(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.
Operators shall submit their request 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.
(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 requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on February 26, 1998.
Ronald L.Vavruska,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 98-5797 Filed 3-6-98; 8:45 am]
BILLING CODE 4910-13-U
