[Federal Register Volume 63, Number 144 (Tuesday, July 28, 1998)]
[Proposed Rules]
[Pages 40226-40228]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-19633]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-48-AD]
RIN 2120-AA64
Airworthiness Directives; Pratt & Whitney JT8D-1, -1A, -1B, -7, -
7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR 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) in the Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -
7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR Turbofan
Engines Engine Manual (EM) 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 October 26, 1998.
ADDRESSES: Submit comments in triplicate to the FederalAviation
Administration (FAA), New England Region, Office of the Regional
Counsel, Attention: Rules Docket No. 98-ANE-48-AD, 12 New England
Executive Park, Burlington, MA 01803-5299. Comments may also be sent
via the Internet using the following address: ``engineprop@faa.dot.gov''. 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: Christopher Spinney, Aerospace
Engineer, Engine Certification Office, FAA, Engine and Propeller
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299;
telephone (781) 238-7175, 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-48-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-48-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
[[Page 40227]]
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 front compressor front hubs
(fan hubs) and second stage compressor disks which could most likely
result in a safety hazard to the airplane in the event of a hub or 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 Manual.
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, 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 PW JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17,
-17A, -17R, and -17AR Turbofan Engines EM, and, for air carriers, the
approved continuous airworthiness maintenance program. PW, the
manufacturer of JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -
15A, -17, -17A, -17R, and -17AR 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 11,278 engines of the affected design in
the worldwide fleet. The FAA estimates that 5,821 engines installed on
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 7 work hours per engine to accomplish the
proposed actions. The average labor rate is $60 per work hour. Based on
these figures, the total cost impact of the proposed AD on U.S.
operators is estimated to be $2,444,820.
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-48-AD.
[[Page 40228]]
Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -
7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR series
turbofan engines, installed on but not limited to Boeing 727 and 737
series and McDonnell Douglas DC-9 series aircraft.
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 Time Limits Section (TLS) of the Pratt & Whitney (PW)
JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A,
-17R, and -17AR Turbofan Engines Engine Manual (EM), part number
481672, and for air carrier operations revise the approved
continuous airworthiness maintenance program, by adding the
following:
``6. Critical Life Limited Part Inspection
A. Inspection Requirements:
(1) This section has the definitions for individual engine piece
parts and the inspection procedures which are necessary when these
parts are removed from the engine.
(2) It is necessary to do the inspection procedures of the piece
parts in paragraph B when:
(a) The part is removed from the engine and disassembled to the
level specified in paragraph B and--
(b) The part has accumulated more than 100 cycles since the last
piece part inspection, provided that the part was not damaged by or
related to the cause for it's removal from the engine.
(3) The inspections specified in this section do not replace or
make not necessary other recommended inspections for these parts or
other parts.
B. Parts Requiring Inspection
Note: Piece part is defined as any of the listed parts with all
the blades removed.
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Engine manual description Section Inspection
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Hub (Disk), 1st Stage Compressor:
491201........................... 72-33-31 -XX,-02,-03
496501........................... 72-33-31 -XX,-02,-03
504101........................... 72-33-31 -XX,-02,-03
515201........................... 72-33-31 -XX,-02,-03
594301........................... 72-33-31 -XX,-02,-03
640501........................... 72-33-31 -XX,-02,-03
640601........................... 72-33-31 -XX,-02,-03
743301........................... 72-33-31 -XX,-02,-03
749701........................... 72-33-31 -XX,-02,-03
749801........................... 72-33-31 -XX,-02,-03
750001........................... 72-33-31 -XX,-02,-03
750101........................... 72-33-31 -XX,-02,-03
778901........................... 72-33-31 -XX,-02,-03
791401........................... 72-33-31 -XX,-02,-03
791501........................... 72-33-31 -XX,-02,-03
791601........................... 72-33-31 -XX,-02,-03
791701........................... 72-33-31 -XX,-02,-03
791801........................... 72-33-31 -XX,-02,-03
806001........................... 72-33-31 -XX,-02,-03
806101........................... 72-33-31 -XX,-02,-03
817401........................... 72-33-31 -XX,-02,-03
844401........................... 72-33-31 -XX,-02,-03
845401........................... 72-33-31 -XX,-02,-03
848001........................... 72-33-31 -XX,-02,-03
848101........................... 72-33-31 -XX,-02,-03
Disk, 2nd Stage Compressor....... 72-33-31 -XX,-02,-03
482502........................... 72-33-33 -XX
502502........................... 72-33-33 -XX
520602........................... 72-33-33 -XX
570302........................... 72-33-33 -XX
570402........................... 72-33-33 -XX
678202........................... 72-33-33 -XX
730202........................... 72-33-33 -XX
730302........................... 72-33-33 -XX
730402........................... 72-33-33 -XX
740502........................... 72-33-33 -XX
745702........................... 72-33-33 -XX
745902........................... 72-33-33 -XX
746002........................... 72-33-33 -XX
746802........................... 72-33-33 -XX
760402........................... 72-33-33 -XX
760502........................... 72-33-33 -XX
807502........................... 72-33-33 -XX
5002402-01....................... 72-33-33 -XX
790832 (Disk assembly)........... 72-33-33 -XX''
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(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 section
in the EM.
(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 in the EM 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 Chapter 05-11-00, titled Time Limits, in the EM
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 July 16, 1998.
Jay J. Pardee,
Manager, Engine and Propeller Directorate,
Aircraft Certification Service.
[FR Doc. 98-19633 Filed 7-27-98; 8:45 am]
BILLING CODE 4910-13-P
