[Federal Register Volume 65, Number 207 (Wednesday, October 25, 2000)]
[Rules and Regulations]
[Pages 63793-63795]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-27431]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 2000-NE-47-AD; Amendment 39-11947; AD 2000-22-01]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan
Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Pratt & Whitney (PW) PW4000 series turbofan
engines that are equipped with the high pressure compressor (HPC)
cutback stator (CBS) configuration and that are used on Boeing 747,
Boeing 767, and McDonnell Douglas MD-11 series airplanes. This action
requires Operators to limit the number of engines with the HPC CBS
configuration to one per airplane, and prohibits installation of
engines with HPC modules modified after the effective date of this AD
to incorporate the HPC CBS configuration. This amendment is prompted by
reports of HPC surges in engines that have the HPC CBS configuration.
The actions specified in this AD are intended to prevent a multiple-
engine power loss due to HPC surges, which could result in engine power
loss at a critical phase of flight such as takeoff or climb.
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DATES: Effective November 9, 2000.
Comments for inclusion in the Rules Docket must be received on or
before December 26, 2000.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 2000-NE-47-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``[email protected].'' Comments sent via the Internet must contain the
docket number in the subject line.
The docket file for this AD 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: Peter White, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7128, fax (781) 238-7199.
SUPPLEMENTARY INFORMATION: The FAA has been informed of nine surge
events on PW4000 series engines that incorporate the HPC CBS
configuration and that are used on Boeing 747, Boeing 767, and
McDonnell Douglas MD-11 series airplanes. The surges were as follows:
two occurred during takeoff,
two occurred during climb,
four occurred during ground testing,
one occurred in a test cell shortly after selecting
takeoff power.
The FAA issued AD 99-17-16, Amendment 39-11263 on August 12, 1999
(64 FR 45426, August 20, 1999). That AD requires short-term criteria
for limiting the number of engines with potentially reduced stability
on each airplane to no more than one engine, requires initial and
repetitive on-wing or test cell cold-engine HPC stability tests,
requires removal of engines from service that fail on-wing test
acceptance criteria, and allows a follow-on test cell stability test.
AD 99-17-16 also establishes required intervals for stability testing
of the remaining engine with potentially reduced stability on the
airplane and requirements for reporting test data. That amendment was
prompted by a report of a dual-engine HPC surge event and reports of
single-engine HPC surge events during the takeoff and climb phases of
flight.
Subsequent to that AD, PW introduced a new design and full
authority digital electronic control (FADEC) logic changes to address
the problem of HPC rear stage surges. After the two latest surge events
that occurred during takeoff, PW's preliminary analysis indicates that
these events originated in the front stages of the HPC. A Weibull
analysis conducted by PW revealed that the takeoff surge rate on
engines with the HPC CBS configuration is about 11 times higher than
the historical takeoff surge of the HPC non-CBS configuration. This
condition, if not corrected, could result in a multiple-engine power
loss due to HPC surges, which could result in engine power loss at a
critical phase of flight such as takeoff or climb. The investigation is
on-going and we may take further rulemaking action. We have coordinated
with the Transport Airplane Directorate, the office responsible for
certificating the airplanes on which the engines are installed.
Applicability of AD 99-17-16 to HPC CBS Engines
The stability testing defined in AD 99-17-16 is ineffective in
evaluating the stability of the HPC CBS configuration, because those
tests assess rear stage HPC stability and not front stage HPC
stability, which is limiting for the HPC CBS configuration engines. The
FAA has issued alternative methods of compliance (AMOC's) to PW
intended for use by all operators for certain HPC CBS configuration
engines exempting them from the initial and repetitive testing
requirements of AD 99-17-16. These AMOC's are not affected by this AD.
Requirements of This AD
Since an unsafe condition has been identified that is likely to
exist or develop on other PW4000 series turbofan engines of the same
type design, this AD is being issued to prevent a multiple-engine power
loss due to HPC surges, which could result in engine power loss at a
critical phase of flight, such as takeoff or climb. This AD requires
limiting the number of engines with the HPC CBS configuration
installed, and that are used on Boeing 747, Boeing 767, and McDonnell
Douglas MD-11 series airplanes, to one on each airplane according to
the cyclic limits specified in this AD. This AD also prohibits using
engines with HPC modules that incorporated PW service bulletin (SB)
PW4ENG 72-706, Revision No. 3, dated July 17, 2000, or earlier
revision, or SB PW4ENG 72-711, dated June 13, 2000, after the effective
date of this AD.
Immediate Adoption of This AD
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this action must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket No. 2000-NE-47-AD.'' The postcard will be date stamped and
returned to the commenter.
Regulatory Impact
This rule does not have federalism implications, as defined in
Executive Order 13132, because it would not have a substantial direct
effect 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. Accordingly,
the FAA has not consulted with state authorities prior to publication
of this rule.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to
[[Page 63795]]
correct an unsafe condition in aircraft, and is not a ``significant
regulatory action'' under Executive Order 12866.
It has been determined further that this action involves an
emergency regulation under DOT Regulatory Policies and Procedures (44
FR 11034, February 26, 1979). If it is determined that this emergency
regulation otherwise would be significant under DOT Regulatory Policies
and Procedures, a final regulatory evaluation will be prepared and
placed in the Rules Docket. A copy of it, if filed, 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, 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:
2000-22-01 Pratt & Whitney: Amendment 39-11947. Docket 2000-NE-47-
AD.
Applicability
This airworthiness directive (AD) is applicable to PW4050,
PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4460, and PW4462
turbofan engines that have high pressure compressor (HPC) modules
that have incorporated Pratt & Whitney (PW) cutback stator (CBS)
configuration service bulletin (SB) PW4ENG 72-706, Revision 3, dated
July 17, 2000, or earlier Revision, or SB PW4ENG 72-711, dated June
13, 2000. These engines are used on, but not limited to, Boeing 747,
Boeing 767, and McDonnell Douglas MD-11 series airplanes. An HPC
module that has incorporated PW SB PW4ENG 72-706, Revision 3, dated
July 17, 2000, or earlier Revision, or PW4ENG 72-711, dated June 13,
2000, will have the letters ``CB'' after the HPC module serial
number on the HPC module data plate.
Note 1: This 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 (e) 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
Compliance with this AD is required as indicated, unless already
done.
To prevent a multiple-engine power loss due to HPC surges, which
could result in engine power loss at a critical phase of flight such
as takeoff or climb, do the following:
Number of Cycles Until Number of Engines Must Be Limited
(a) Limit the number of engines with the HPC CBS configuration
to one on each airplane within 100 cycles-in-service (CIS) of the
effective date of this AD, or before the cyclic limits defined in
the table below, whichever occurs later:
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Type of airplane Comply by
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(1) Two................................... Before 390 cycles-since-new
engine.................................... (CSN) or cycles-since-HPC
module overhaul (CSO).
(2) Three................................. Before 340 CSN or CSO.
engine....................................
(3) Four.................................. Before 305 CSN or CSO.
engine....................................
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Special Conditions for Installing More Than One HPC CBS Engine on An
Airplane
(b) Two HPC CBS configuration engines may be used on an airplane
only under the following conditions:
(1) One engine with an HPC CBS configuration has fewer than 25
CSN or CSO, and
(2) The remaining engine has fewer than 615 CSN or CSO, and
(3) The airplane is operated for fewer than 25 CIS in this
configuration.
HPC Modules at HPC Module Overhaul
(c) Engines with HPC modules that have been modified to
incorporate PW SB PW4ENG 72-706, Revision 3 dated July 17, 2000, or
earlier Revision, or SB PW4ENG 72-711, dated June 13, 2000, after
the effective date of this AD, are not eligible for installation on
an airplane.
Definitions
(d) For the purposes of this AD, an HPC module overhaul is
defined as whenever the HPC stage 12 through 15 blade tip clearances
are restored to the clearances specified in the applicable fits and
clearances section of the engine manual during the shop visit.
Alternative Methods of Compliance
(e) 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 (ECO).
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, ECO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the ECO.
Effective Date of This AD
(f) This amendment becomes effective on November 9, 2000.
Issued in Burlington, Massachusetts, on October 19, 2000.
Thomas A. Boudreau, Acting Manager, Engine and Propeller Directorate,
Aircraft Certification Service.
[FR Doc. 00-27431 Filed 10-24-00; 8:45 am]
BILLING CODE 4910-13-U