[Federal Register Volume 63, Number 214 (Thursday, November 5, 1998)]
[Proposed Rules]
[Pages 59743-59746]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-29603]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-66-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 proposal would require revisions to the Time Limits
Section (TLS) of the manufacturer's Engine Manuals (EMs) for Pratt &
Whitney (PW) PW4000 series turbofan engines to include required
enhanced inspection of selected critical life-limited parts at each
piece-part exposure. This proposal would also require an air carrier's
approved continuous airworthiness maintenance program to incorporate
these inspection procedures. Air carriers with an approved continuous
airworthiness maintenance program would be allowed to either maintain
the records showing the current status of the inspections using the
record keeping system specified in the air carrier's maintenance
manual, or establish an acceptable alternate method of record keeping.
This proposal is prompted by an FAA study of in-service events
involving uncontained failures of critical rotating engine parts which
indicated the need for improved inspections. The improved inspections
are needed to identify those critical rotating parts with conditions,
that if allowed to continue in service, could result in uncontained
failures. The actions specified by this proposed AD are intended to
prevent critical life-limited rotating engine part failure, which could
result in an uncontained engine failure and damage to the airplane.
DATES: Comments must be received by February 3, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 98-ANE-66-AD, 12 New England
Executive Park,
[[Page 59744]]
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.
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:
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 98-ANE-66-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. 98-ANE-66-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
A recent FAA study analyzing 15 years of accident data for
transport category airplanes identified several failure mode root
causes that can result in serious safety hazards to transport category
airplanes. This study identified uncontained failure of critical life-
limited rotating engine parts as the leading engine-related safety
hazard to airplanes. Uncontained engine failures have resulted from
undetected cracks in rotating parts that initiated and propagated to
failure. Cracks can originate from causes such as unintended excessive
stress from the original design, or they may initiate from stresses
induced from material flaws, handling damage, or damage from machining
operations. The failure of rotating parts can present a significant
safety hazard to the airplanes by release of high energy fragments that
could injure passengers or crew by penetration of the cabin, damage
flight control surfaces, sever flammable fluid lines, or otherwise
compromise the airworthiness of the airplane.
Accordingly, the FAA has developed an intervention strategy to
significantly reduce uncontained engine failures. This intervention
strategy was developed after consultation with industry and will be
used as a model for future initiatives. This intervention strategy is
to conduct enhanced, nondestructive inspections of fan disks which
could most likely result in a safety hazard to the airplane in the
event of a disk fracture. The need for additional rule making is also
being considered by the FAA. Future ADs may be issued introducing
additional intervention strategies to further reduce or eliminate
uncontained engine failures.
Properly focused enhanced inspections require identification of the
parts whose failure presents the highest safety hazard to the airplane,
identifying the most critical features to inspect on these parts, and
utilizing inspection procedures and techniques that improve crack
detection. The FAA, with close cooperation of the engine manufacturers,
has completed a detailed analysis that identifies the most safety
significant parts and features, and the most appropriate inspection
methods.
Critical life-limited high energy rotating parts are currently
subject to some form of recommended crack inspection when exposed
during engine maintenance or disassembly. As a result of this AD, the
inspections currently recommended by the manufacturer will become
mandatory for those parts listed in the compliance section.
Furthermore, the FAA intends that additional mandatory enhanced
inspections resulting from this AD serve as an adjunct to the existing
inspections. The FAA has determined that the enhanced inspections will
significantly improve the probability of crack detection while the
parts are disassembled during maintenance. All mandatory inspections
must be conducted in accordance with detailed inspection procedures
prescribed in the manufacturer's Engine Cleaning, Inspection, and
Repair (CIR) manuals.
Additionally, this AD allows for air carriers operating under the
provisions of 14 CFR part 121 with an FAA-approved continuous
airworthiness maintenance program, and entities with whom those air
carriers make arrangements to perform this maintenance, to verify
performance of the enhanced inspections by retaining the maintenance
records that include the inspections resulting from this AD, provided
that the records include the date and signature of the person
performing the maintenance action. These records must be retained with
the maintenance records of the part, engine module, or engine until the
task is repeated. This will establish a method of record preservation
and retrieval typical to those in existing continuous airworthiness
maintenance programs. Instructions must be included in an air carrier's
maintenance manual providing procedures on how this record preservation
and retrieval system will be implemented and integrated into the air
carrier's record keeping system.
For engines or engine modules that are approved for return to
service by an authorized FAA-certificated entity and that are acquired
by an operator after the effective date of this AD, the mandatory
enhanced inspections need not be accomplished until the next piece-part
opportunity. For example, there is no need for an operator to
disassemble to piece-part level an engine or module returned to service
by an FAA-certificated facility simply because that engine or module
was previously operated by an entity not required to comply with this
AD. Furthermore, the FAA intends for operators to perform the enhanced
inspections of these parts at the next piece-part opportunity following
the initial acquisition, installation, and removal of the part
following the effective date of this AD. For piece parts that have not
been approved for return to service prior to the effective date of this
AD, the FAA does intend that the mandatory enhanced inspections
required by this AD be performed before such parts are approved for
return to service. Piece parts that have been approved for return to
service prior to the effective date of this AD may be installed;
however,
[[Page 59745]]
enhanced inspection will be required at the next piece-part
opportunity.
This proposal would require, within the next 30 days after the
effective date of this AD, revisions to the Time Limits Section (TLS)
of the Engine Manuals for PW4000 series turbofan engines, and, for air
carriers, the approved continuous airworthiness maintenance program.
Pratt & Whitney, the manufacturer of PW4000 series turbofan engines,
used on 14 CFR part 25 airplanes has provided the FAA with a detailed
proposal that identifies and prioritizes the critical life-limited
rotating engine parts with the highest potential to hazard the airplane
in the event of failure, along with instructions for enhanced, focused
inspection methods. The enhanced inspections resulting from this AD
will be conducted at piece-part opportunity, as defined below in the
compliance section, rather than specific time inspection intervals.
There are approximately 1,900 engines of the affected design in the
worldwide fleet. The FAA estimates that 450 engines installed on
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 8 work hours for the fan disk inspection.
The average labor rate is $60 per work hour. Based on these figures,
and using recent shop visit rate data, the total cost impact of the
proposed AD on U.S. operators is estimated to be $70,000 per year.
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 98-ANE-66-AD.
Applicability: Pratt & Whitney PW4050, PW4052, PW4056, PW4060,
PW4060A, PW4062, PW4060C, PW4152, PW4156, PW4156A, PW4158, PW4160,
PW4460, PW4462, PW4164, PW4168, PW4074, PW4074D, PW4077, PW4077D,
PW4084, PW4084D, and PW4090 series turbofan engines, installed on
but not limited to Airbus A300, A310, and A330 series, Boeing 747,
767, 777 series, and McDonnell Douglas MD-11 series airplanes.
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 (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 prevent critical life-limited rotating engine part failure,
which could result in an uncontained engine failure and damage to
the airplane, accomplish the following:
(a) Within the next 30 days after the effective date of this AD,
revise the manufacturer's Time Limits section of the manufacturer's
Engine Manual, Part Numbers (P/Ns) 50A605, 50A443, 51A342, 50A822,
51A751, and 51A345, as applicable, for Pratt & Whitney PW4050,
PW4052, PW4056, PW4060, PW4060A, PW4062, PW4060C, PW4152, PW4156,
PW4156A, PW4158, PW4160, PW4460, PW4462, PW4164, PW4168, PW4074,
PW4074D, PW4077, PW4077D, PW4084, PW4084D, and PW4090 series
turbofan engines, and for air carrier operations revise the approved
continuous airworthiness maintenance program, by adding the
following:
``MANDATORY INSPECTIONS
(1) Perform inspections of the following parts at each piece-part
opportunity in accordance with the instructions provided in the PW4000
series Engine Cleaning, Inspection, and Repair (CIR) Manuals:
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Manual CIR
Part nomen P/N section Inspection manual
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Hub, LPC Assembly.......................... 50B221 (50B201 Detail)........ 72-31-07 02 51A357
Hub, LPC Assembly.......................... 50B321 (50B301 Detail)........ 72-31-07 02 51A357
Hub, LPC Assembly.......................... 51B321 (51B301 Detail)........ 72-31-07 02 51A357
Hub, LPC Assembly.......................... 52B021 (52B001 Detail)........ 72-31-07 02 51A357
Hub, LPC Assembly.......................... 51B631 (50B601 Detail)........ 72-31-07 02 51A750
Hub, LPC Assembly.......................... 51B821 (51B801 Detail)........ 72-31-07 02 51A750
Hub, LPC Assembly.......................... 52B521 (52B501 Detail)........ 72-31-07 02 51A750
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(2) For the purposes of these mandatory inspections, piece-part
opportunity means:
(i) The part is considered completely disassembled when done in
accordance with the disassembly instructions in the engine
manufacturer's Engine Manual; and
(ii) The part has accumulated more than 100 cycles in service since
the last piece-part opportunity inspection, provided that the part was
not damaged or related to the cause for its removal from the engine.''
(b) Except as provided in paragraph (c) of this AD, and
notwithstanding contrary provisions in section 43.16 of the Federal
Aviation Regulations (14 CFR 43.16), these mandatory inspections
shall be performed only in accordance with the Time Limits
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section of the applicable PW4000 series Engine Manuals.
(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 Engine Certification Office. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector (PMI), who may add comments and then send it
to the 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.
(d) 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 airplane to a location where
the requirements of this AD can be accomplished.
(e) The records of the mandatory inspections required as a
result of revising the Time Limits section of the PW4000 series
Engine Manuals and the air carrier's continuous airworthiness
maintenance program as provided by paragraph (a) of this AD shall be
maintained by FAA-certificated air carriers which have an approved
continuous airworthiness maintenance program in accordance with the
record keeping system currently specified in their manual required
by sections 121.369 of the Federal Aviation Regulations (14 CFR
121.369); or, in lieu of the record showing the current status of
each mandatory inspection required by sections 121.380(a)(2)(vi) of
the Federal Aviation Regulations (14 CFR 121.380(a)(2)(vi)),
certificated air carriers may establish an approved alternate system
of record retention that provides a method for preservation and
retrieval of the maintenance records that include the inspections
resulting from this AD, and include the policy and procedures for
implementing this alternate method in the air carrier's maintenance
manual required by sections 121.369 (c) of the Federal Aviation
Regulations (14 CFR 121.369 (c)); however, the alternate system must
be accepted by the appropriate PMI and require the maintenance
records be maintained either indefinitely or until the work is
repeated.
Note 3: These record keeping requirements apply only to the
records used to document the mandatory inspections required as a
result of revising the Time Limits section of the PW4000 series
Engine Manuals as provided in paragraph (a) of this AD, and do not
alter or amend the record keeping requirements for any other AD or
regulatory requirement.
Issued in Burlington, Massachusetts, on October 30, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 98-29603 Filed 11-4-98; 8:45 am]
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