[Federal Register Volume 64, Number 136 (Friday, July 16, 1999)]
[Rules and Regulations]
[Pages 38301-38302]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-17554]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-55-AD; Amendment 39-11220; AD 99-15-01]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Pratt & Whitney PW4000 series turbofan engines, 
that reduces life limits of certain 4th stage low pressure turbine 
(LPT) disks. It also allows the original life limits of the disks to be 
restored if reoperation is performed to incorporate the original 
slotted cooling hole configuration. This amendment 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 this AD are intended to prevent an 
uncontained disk failure and damage to the aircraft.

DATES: Effective September 14, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 14, 1999.

ADDRESSES: The service information referenced in this AD 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) 565-8770. This information may be 
examined at the Federal Aviation Administration (FAA), New England 
Region, Office of the Regional Counsel, 12 New England Executive Park, 
Burlington, MA; or at the Office of the Federal Register, 800 North 
Capitol Street, NW, suite 700, Washington, DC.

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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to Pratt & Whitney Model PW4056, 
PW4152, PW4156A, PW4164, PW4168, and PW4460 turbofan engines was 
published in the Federal Register on March 9, 1998 (63 FR 11381). That 
action proposed to reduce life limits of affected 4th stage low 
pressure turbine (LPT) disks, identified by serial number (S/N). It 
would also allow the original life limits to be restored, if 
reoperation is performed to incorporate the slotted cooling air 
configuration.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter states that it does not own any of the disks affected 
by this AD, and will therefore not be affected by it. The commenter, 
however, states that the 4th stage LPT disk was subjected to a design 
change but retained the same part number. The commenter states that for 
tracking purposes it is desirable to change the part number. The FAA 
agrees with the concept; however, this issue addresses practices at the 
manufacturer and not this action, since both part number and serial 
numbers are identified for tracking purposes. The FAA will communicate 
this request to the manufacturer for future considerations.
    One commenter states that the economic analysis should be revised 
to note that the labor cost is accurate when the engine is torn down to 
obtain access to the LPT. The FAA concurs and has added this language 
to the economic analysis of this final rule.
    Two commenters state that they do not own any of the affected disks 
and that therefore would not be affected by the proposed rule.
    One commenter supports the rule as proposed.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed. The FAA has 
determined that this change will neither increase the economic burden 
on any operator nor increase the scope of the AD.
    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 that will be affected by this 
AD, but if one were installed, it would take approximately 4 work hours 
per engine to accomplish the required actions when the engine is torn 
down to obtain access to the LPT, and that the average labor rate is 
$60 per work hour. Required parts will cost approximately $240 per 
engine. Based on these figures, the total cost impact per engine is 
estimated to be $480.
    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air Transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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.

[[Page 38302]]

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

99-15-01  Pratt & Whitney: Amendment 39-11220. Docket 97-ANE-55-AD.

    Applicability: Pratt & Whitney Model PW4056, PW4152, PW4156A, 
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 Industrie 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 and 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 or 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 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the airplane to a location where the 
requirements of this AD can be accomplished.
    (e) The actions required by this AD shall be done in accordance 
with the following PW SBs:

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               Document No.                            Pages                              Dates
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PW4G=100-72-105...........................  1-19.......................  November 12, 1997.
Total Pages: 19
PW4ENG 72-657.............................  1-22.......................  November 25, 1997.
Total Pages: 22
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This incorporation by reference was approved by the Director of the 
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. Copies 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) 565-8770. 
Copies may be inspected at the FAA, New England Region, Office of 
the Regional Counsel, 12 New England Executive Park, Burlington, MA; 
or at the Office of the Federal Register, 800 North Capitol Street 
NW, suite 700, Washington, DC.
    (f) This amendment becomes effective on September 14, 1999.

    Issued in Burlington, Massachusetts, on July 6, 1999.
David A. Downey,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 99-17554 Filed 7-15-99; 8:45 am]
BILLING CODE 4910-13-M