[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]


 ========================================================================
 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  

[[Page 11381]]


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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: ``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. 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