[Federal Register Volume 63, Number 117 (Thursday, June 18, 1998)]
[Proposed Rules]
[Pages 33295-33296]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-16271]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-ANE-53-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 (PW)
PW4000 series turbofan engines not incorporating modifications
described in certain PW service bulletins listed in the applicability
section. This proposal would 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. This proposal is
prompted by reports of HPC surge caused by excessive HPC rear stage
rotor-to-case clearance. The actions specified by the proposed 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: Comments must be received by August 17, 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-53-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, 400 Main St., East Hartford, CT 06108;
telephone (860) 565-6600, 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: 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-53-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-53-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
The Federal Aviation Administration (FAA) has received reports of
certain Pratt & Whitney (PW) PW4000 series turbofan engine power loss
events occurring frequently during a critical phase of flight such as
takeoff or climb. The events have led to the flight crew conducting
rejected takeoffs and to engine power loss or shutdown events in
flight. A rejected takeoff could result in the airplane overrunning the
runway, incurring airplane damage, and injuring airplane occupants.
Engine power loss or shutdown during takeoff also significantly
increases crew workload during a critical phase of flight. The
investigations into these events revealed that they were caused by high
pressure compressor (HPC) surge that could require crew action to
recover. Further investigation revealed that the surge results from
excessive HPC rear stage rotor-to-case clearance. This condition, if
not corrected, could result in HPC surge, which can result in engine
power loss at a critical phase of flight such as takeoff.
The FAA has reviewed and approved the technical contents of the
following PW Service Bulletins (SB): PW4ENG-72-484, Revision 3, dated
July 1, 1997, that describes procedures for HPC blade tip grinding at
the rotor assembly and introduces HPC aluminum oxide blade tip coating
in stages 9 through 15 compatible with tip grinding; PW4ENG-72-486,
Revision 1, dated November 23, 1994, that describes procedures for
modifying HPC 8th through 14th stage stators; PW4ENG-72-514, Revision
1, dated August 2, 1996, that describe procedures for high pressure
turbine (HPT) hardware modifications to accommodate the incorporation
of 1st stage HPT vanes with increased airflow area; and PW4ENG-72-575,
Revision 1, dated June 30, 1997, that describes procedures for
incorporating HPC 13th-15th stage zirconium oxide tips.
[[Page 33296]]
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 require grinding of the HPC blade tips at the rotor
assembly and incorporation of HPC stage 9 through 12 aluminum oxide
blade tips, modification of HPC 8th through 14th stage stators,
modification of HPT hardware to accommodate incorporation of 1st stage
HPT vanes with increased airflow area and incorporation of these vanes,
and incorporation of HPC 13th through 15th stage zirconium oxide blade
tips, within 1,400 cycles in service after the effective date of this
AD, or prior to June 30, 1999, whichever occurs first. The calendar
end-date was based upon analysis of test data and service experience
data. The actions would be required to be accomplished in accordance
with the SBs described previously.
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
proposed AD. Required parts would cost approximately $20,000 per
engine. Based on these figures, the total cost impact of the proposed
AD, including labor costs, is estimated to be $1,220,000.
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-53-AD.
Applicability: Pratt & Whitney (PW) Model PW4152, PW4056,
PW4156, PW4256, PW4052, PW4158, W4060, 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 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.
(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.
Issued in Burlington, Massachusetts, on June 11, 1998.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 98-16271 Filed 6-17-98; 8:45 am]
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