[Federal Register Volume 66, Number 56 (Thursday, March 22, 2001)]
[Proposed Rules]
[Pages 16017-16019]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-7081]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 2000-NE-49-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: The Federal Aviation Administration (FAA) proposes to adopt a
new airworthiness directive (AD) that is applicable to certain models
of Pratt & Whitney (PW) PW4000 series turbofan engines. This proposal
would require operators to perform initial and repetitive inspections
for cracking of high pressure compressor (HPC) front drum rotors based
on cycle usage. This proposal would also require the removal from
service of any cracked HPC front drum rotors. This proposal is prompted
by reports that seven HPC drum rotors have been found cracked on the
spacer surface between the 6th and 7th stage disks. The actions
specified by the proposed AD are intended to detect premature cracking
of the HPC drum rotor that could result in an uncontained engine
failure and damage to the airplane.
DATES: Comments must be received by May 21, 2001.
ADDRESSES: Submit comments to the Federal Aviation Administration
(FAA), New England Region, Office of the Regional Counsel, Attention:
Rules Docket No. 2000-NE-49-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.
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 Street, East Hartford, CT
06108. 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: Tara Goodman, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington MA 01803-5299; telephone: 781-
238-7130, 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 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 action may be changed in light of the
comments received.
[[Page 16018]]
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 action must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 2000-NE-49-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRM's
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. 2000-NE-49-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
This proposal is prompted by reports that seven HPC front drum
rotors have been found cracked in the axial direction on the spacer
surface between the 6th and 7th stage disks. These axial cracks may
propagate into the disk and lead to compressor disk fracture, which
could result in an uncontained engine failure. The manufacturer is
investigating the cause of the cracking. There is currently no
terminating action to the repetitive inspection requirements of the
proposed AD. This proposed rule may be revised based on the results of
the manufacturer's investigation.
Manufacturer's Service Information
The FAA has reviewed and approved the technical contents of PW
Alert Service Bulletin (ASB) No. PW4ENG A72-722, dated September 29,
2000. That ASB provides procedures for operators to perform on-wing and
off-wing initial and repetitive HPC drum rotor borescope inspections.
Differences Between Manufacturer's Service Information and this AD
Although ASB No. PW4ENG A72-722, dated September 29, 2000, exempts
PW4158 engine serial numbers P728534 through P728546, from the
inspection requirements, this AD includes those engines in the initial
and repetitive inspections and requires replacing any drum rotor that
is cracked. The FAA has determined that there is insufficient data to
permit the exception of these particular engines from the proposed
inspection requirements.
Also, although ASB No. PW4ENG A72-722, dated September 29, 2000,
provides procedures for operators to perform off-wing initial and
repetitive HPC drum rotor inspections, the off-wing requirements are
not mandated by the proposed rule. The FAA has evaluated a 20-year
cumulative risk assessment and has determined that an acceptable level
of safety will be met by requiring the on-wing inspections at the
cyclic intervals detailed in the ASB.
ASB No. PW4ENG A72-722, dated September 29, 2000, states in item 12
of the Accomplishment Instructions for the on-wing inspection that an
eddy current nondestructive inspection must be done within five engine
cycles of finding a crack indication. The FAA has determined that if
confirmation of cracking is necessary, an eddy current inspection must
be conducted prior to further flight.
Proposed Actions
Since an unsafe condition has been identified that is likely to
exist or develop on other PW4000 series turbofan engines of this same
type design, the proposed AD would require operators to perform initial
borescope inspections on HPC drum rotors before accumulating 1,500
cycles-since-new (CSN) on the effective date of this AD. This proposed
AD would also require thereafter, inspections within 2,200 cycles-
since-last-inspection, and the removal from service of any cracked HPC
front drum rotor. The compliance intervals were established by analysis
of service data and evaluation of a risk analysis. The actions would be
required to be accomplished in accordance with the ASB described
previously.
Economic Analysis
The FAA estimates that there are 1,970 engines of the affected
design in the worldwide fleet, and that 538 engines installed on
aircraft of U.S. registry would be affected by this proposed AD. The
FAA also estimates that it would take approximately 2.5 work hours per
engine to accomplish the proposed on-wing inspection, and that the
average labor rate is $60 per work hour. It is estimated that three
engines would be found with cracked HPC front drum rotors in the time
frame of one year. Approximately 269 engines will be inspected on
average per year. The cost of removal and reinstallation of an engine
is approximately $10,000, and the cost of replacing the HPC front drum
rotor is approximately $750,000. Required replacement parts would cost
$356,130 per engine. Based on these figures, the total cost impact per
year of the proposed AD for accomplishing initial inspections and
replacing HPC front drum rotors, on U.S. operators is estimated to be
$3,388,730.
Regulatory Impact
This proposal 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 proposal.
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. 2000-NE-49-AD.
Applicability: This airworthiness directive (AD) applies to Pratt &
Whitney (PW) models
[[Page 16019]]
PW4052, PW4056, PW4060, PW4062, PW4152, PW4156A, PW4158, PW4460, and
PW4462 turbofan engines. These engines are installed on but not
limited to Boeing 747, 767, McDonnell Douglas MD-11, Airbus
Industrie A300, and A310 series airplanes.
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 (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 detect premature cracking of the high pressure compressor
(HPC) front drum rotor, that could result in an uncontained engine
failure and damage to the airplane, accomplish the following:
Initial Inspection
(a) Perform an initial inspection in accordance with the
Accomplishment Instructions, On-Wing paragraphs 1 through 13, of PW
Alert Service Bulletin (ASB) No. PW4ENG A72-722, dated September 29,
2000, as follows:
(1) Perform an initial inspection of HPC front drum rotors
before accumulating 1,500 cycles-since-new.
(2) If the presence of a crack needs to be confirmed, perform an
eddy current inspection (ECI) before further flight.
(3) If the presence of a crack is confirmed, remove and replace
with a serviceable HPC front drum rotor before further flight.
Repetitive Inspections
(b) Thereafter, perform inspections within 2,200 cycles-since-
last-inspection, in accordance with the Accomplishment Instructions,
On-Wing paragraphs 1 through 13, of PW ASB No. PW4ENG A72-722, dated
September 29, 2000.
(1) If the presence of a crack needs to be confirmed, perform an
ECI before further flight.
(2) If the presence of a crack is confirmed, remove and replace
with a serviceable HPC front drum rotor before further flight.
Alternative Methods of Compliance
(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 (ECO).
Operators shall submit their request through an appropriate Federal
Aviation Administration (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.
Special Flight Permits
(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.
Issued in Burlington, Massachusetts, on March 14, 2001.
Mark Liptak,
Acting Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 01-7081 Filed 3-21-01; 8:45 am]
BILLING CODE 4910-13-P