Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

[Federal Register Volume 63, Number 219 (Friday, November 13, 1998)]
[Rules and Regulations]
[Pages 63391-63393]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-30320]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-53-AD; Amendment 39-10873; AD 98-23-08]
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 (PW) PW4000 series turbofan 
engines not incorporating modifications described in certain PW service 
bulletins listed in the applicability section, that requires high 
pressure compressor (HPC) blade tip grinding of the rotor assembly, 
installation of aluminum oxide coated HPC blade tips in stages 9 
through 12, modification of HPC 8th through 14th stage stators, 
incorporation of 1st stage high pressure turbine (HPT) vanes with 
increased airflow area which also requires additional HPT hardware 
modifications, and incorporation of HPC 13th-15th stage zirconium oxide 
blade tips. This amendment is prompted by reports of HPC surge caused 
by excessive HPC rear stage rotor-to-case clearance. The actions 
specified by this AD are intended to prevent HPC surge, which can 
result in engine power loss at a critical phase of flight such as 
takeoff or climb.

DATES: Effective January 12, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 12, 1999.

ADDRESSES: The service information referenced in this AD 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 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

[[Page 63392]]

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 certain Pratt & Whitney (PW) 
PW4000 series turbofan engines not incorporating modifications 
described in certain PW service bulletins listed in the applicability 
section was published in the Federal Register on June 18, 1998 (63 FR 
33295). That action proposed to require high pressure compressor (HPC) 
blade tip grinding of the rotor assembly, installation of aluminum 
oxide coated HPC blade tips in stages 9 through 12, modification of HPC 
8th through 14th stage stators, incorporation of 1st stage high 
pressure turbine (HPT) vanes with increased airflow area which also 
requires additional HPT hardware modifications, and incorporation of 
HPC 13th-15th stage zirconium oxide blade tips.
    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 requests a change to the Compliance Section to allow 
the accomplishment of either PW Service Bulletins (SBs) No. PW4ENG-72-
514, or the appropriate nozzle guide vane and TOBI duct section of SB 
PW4ENG-72-504. The commenter wants to have a choice to incorporate the 
pertinent sections of SB PW4ENG-72-504 after the effective date of this 
AD and still comply with the AD. The FAA concurs, provided that all of 
the requirements of that SB are incorporated, since incorporation of 
only the pertinent sections will not produce a certified engine 
configuration. Engines that have incorporated the modifications in SB 
PW4ENG-72-504 already are exempted from the AD based upon the 
applicability. If an operator wants to exercise this choice after the 
effective date of this AD, instead of incorporating the modifications 
in SB PW4ENG-72-514, that choice will produce an airworthy engine to an 
equivalent level of the modifications in SB PW4ENG-72-514. There are 
two other SBs listed in the applicability section: SB PW4ENG-72-490 and 
PW4ENG-72-572 that accomplish equivalent actions to SB PW4ENG-72-504. 
Therefore, a paragraph has been added to the compliance section 
clarifying that if the modifications contained in certain SBs listed in 
the applicability paragraph are incorporated after the effective date 
of this AD, no further action is required.
    One commenter states that it has already complied with the 
requirements of this AD and that those requirements are effective in 
preventing surges from occurring in service.
    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 with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.
    There are approximately 187 engines of the affected design in the 
worldwide fleet. The FAA estimates that there are currently 61 engines 
installed on aircraft of U.S. registry that would be affected by this 
AD. Required parts would cost approximately $20,000 per engine. Based 
on these figures, the total cost impact of the AD, including labor 
costs, is estimated to be $1,220,000.
    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.


Sec. 39.13  [Amended]

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

98-23-08  Pratt & Whitney: Amendment 39-10873. Docket 97-ANE-53-AD.

    Applicability: Pratt & Whitney (PW) Model PW4152, PW4056, 
PW4156, PW4256, PW4052, PW4158, PW4060, PW4160, PW4460, PW4050, 
PW4060A, PW4156A, PW4062, PW4462, PW4060C, and PW4650 turbofan 
engines, not incorporating at least one of the modifications 
described in the PW service bulletins (SBs) and listed in items (1) 
through (6), excluding those engines having a (-3) identifier next 
to the engine model number on the engine data plate. These engines 
are installed on but not limited to Boeing 767 and 747 series 
aircraft, McDonnell Douglas MD-11 series aircraft, and Airbus A310 
and A300-600 series aircraft.
    (1) PW4ENG 72-484, Revision 3, dated July 1, 1997, or earlier 
revisions, PW4ENG 72-486, Revision 1, dated November 23, 1994, or 
original issue.
    (2) PW4ENG 72-484, Revision 3, dated July 1, 1997, or earlier 
revisions, PW4ENG 72-575, Revision 1, dated June 30, 1997, or 
original issue, PW4ENG 72-486, Revision 1, dated November 23, 1994, 
or original issue.
    (3) PW4ENG 72-514, Revision 1, dated August 2, 1996, or original 
issue.
    (4) PW4ENG 72-490, Revision 1, dated August 2, 1994, or original 
issue.
    (5) PW4ENG 72-504, Revision 1, dated May 9, 1995, or original 
issue.
    (6) PW4ENG 72-572, dated June 16, 1995.

    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 (b) 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 high pressure compressor (HPC) surge, which can 
result in engine power loss at a critical phase of flight such as 
takeoff, accomplish the following:
    (a) Within 1,400 cycles in service (CIS) after the effective 
date of this AD, or prior to June 30, 1999, whichever occurs first, 
perform the following modifications:
    (1) Incorporate stage 9 through 12 aluminum oxide blade tips and 
grind HPC

[[Page 63393]]

blade tips at the rotor assembly in accordance with the 
Accomplishment Instructions of PW SB No. PW4ENG-72-484, Revision 3, 
dated July 1, 1997, concurrently with the requirements of paragraph 
(a)(4) of this AD.
    (2) Modify HPC 8th-14th stage stators in accordance with the 
Accomplishment Instructions of PW SB No. PW4ENG-72-486, Revision 1, 
dated November 23, 1994.
    (3) Modify the 1st stage high pressure turbine (HPT) cooling 
duct (TOBI Duct), install a metering plug in the Number 2 bearing 
thrust balance vent tube, and incorporate 1st stage HPT vanes with 
increased airflow area in accordance with the Accomplishment 
Instructions of PW SB No. PW4ENG-72-514, Revision 1, dated August 2, 
1996.
    (4) Incorporate HPC 13th-15th stage zirconium oxide blade tips 
in accordance with the Accomplishment Instructions of PW SB No. 
PW4ENG-72-575, Revision 1, dated June 30, 1997.
    (5) If at any time prior to the compliance time of this AD 
incorporation of the requirements of any one of the SBs, identified 
in items (4), (5), and (6) in the applicability section of this AD 
is accomplished on any engine, then such an engine will not be 
subject to the requirements of this AD and no further action is 
required.
    (b) 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 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.

    (c) 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.
    (d) The actions required by this AD shall be done in accordance 
with the following PW SBs:

----------------------------------------------------------------------------------------------------------------
          Document No.                    Pages                   Revision                      Date
----------------------------------------------------------------------------------------------------------------
PW4ENG-72-484..................  1-16...................  3......................  July 1, 1997.
                                 17-78..................  1......................  November 8, 1994.
                                 79.....................  2......................  March 10, 1995.
                                 80, 81.................  3......................  July 1, 1997.
    Total Pages: 81.
PW4ENG-72-486..................  1-31...................  1......................  November 23, 1994.
    Total Pages: 31.
PW4ENG-72-514..................  1-6....................  1......................  August 2, 1996.
                                 7......................  Original...............  June 23, 1994.
                                 8-35...................  1......................  August 2, 1996.
    Total Pages: 35.
PW4ENG-72-575..................  1-43...................  1......................  June 30, 1997.
    Total Pages: 43.
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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, 400 Main St., 
East Hartford, CT 06108; telephone (860) 565-6600, fax (860) 565-
4503. 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.
    (e) This amendment becomes effective on January 12, 1999.

    Issued in Burlington, Massachusetts, on November 5, 1998.
Mark C. Fulmer,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 98-30320 Filed 11-12-98; 8:45 am]
BILLING CODE 4910-13-P

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