[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]


-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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.

[[Page 63794]]


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:

------------------------------------------------------------------------
             Type of  airplane                        Comply by
------------------------------------------------------------------------
(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....................................
------------------------------------------------------------------------

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