[Federal Register Volume 63, Number 181 (Friday, September 18, 1998)]
[Proposed Rules]
[Pages 49879-49881]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-25008]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-ANE-56-AD]
RIN 2120-AA64
Airworthiness Directives; CFM International CFM56-5 Series
Turbofan Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to CFM International CFM56-5 series
turbofan engines. This proposal would reduce the low cycle fatigue
(LCF) retirement lives for certain high pressure turbine rotor (HPTR)
front air seals, and provide a drawdown schedule for those affected
parts with reduced LCF retirement lives. This proposal is prompted by
results of a refined life analysis performed by the manufacturer that
revealed minimum calculated LCF lives significantly lower than the
published LCF retirement lives. The actions specified by the proposed
AD are intended to prevent a LCF failure of the HPTR front air seal,
which could result in an uncontained engine failure and damage to the
aircraft.
DATES: Comments must be received by October 19, 1998.
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-56-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.
The service information referenced in the proposed rule may be
obtained from CFM International, Technical Publications Department, 1
Neumann Way, Cincinnati, OH 45215; telephone (513) 552-2981, fax (513)
552-2816. 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: Robert Ganley, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (781)
238-7138; 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-56-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-56-AD, 12 New England Executive
Park, Burlington, MA 01803-5299.
Discussion
During a routine engine shop visit, a crack was detected in a CFM
International CFM56-5 high pressure turbine rotor (HPTR) front air
seal. Investigation revealed that the crack initiated from a nick in
the scallop fillet. Review of the manufacturing records revealed
documented surface nicks in the scallop area of the cracked seal, as
well as three other seals. As a precaution, these three additional
seals were removed from service. As part of this investigation, CFM
International also performed a study using updated lifing analyses that
revealed that certain
[[Page 49880]]
HPTR front air seals have minimum calculated low cycle fatigue (LCF)
lives that are significantly lower than published LCF retirement lives.
This condition, if not corrected, could result in a LCF failure of the
HPTR front air seal, which could result in an uncontained engine
failure and damage to the aircraft.
The FAA has reviewed and approved the technical contents of CFM
International CFM56-5 Service Bulletin (SB) No. 72-541, dated July
27,1998, that describes the drawdown schedule for those affected parts
with reduced LCF retirement lives.
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would reduce the LCF retirement lives for certain HPTR
front air seals, and provide a drawdown schedule for those affected
parts with reduced LCF retirement lives. The actions would be required
to be accomplished in accordance with the SB described previously.
There are approximately 863 engines of the affected design in the
worldwide fleet. The FAA estimates that 131 engines installed on
aircraft of U.S. registry would be affected by this proposed AD, and
that it would not take any additional work hours per engine to
accomplish the proposed actions. Assuming that the parts cost is
proportional to the reduction of the LCF retirement lives, the required
parts would cost approximately $14,000 per engine. Based on these
figures, the total cost impact of the proposed AD on U.S. operators is
estimated to be $1,834,000.
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:
CFM International: Docket No. 98-ANE-56-AD.
Applicability: CFM International CFM56-5 series turbofan engines
installed on, but not limited to, Airbus A319 and A320 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 (g) 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 a low cycle fatigue failure of the high pressure
turbine rotor (HPTR) front air seal, which could result in an
uncontained engine failure and damage to the aircraft, accomplish
the following:
(a) Remove from service CFM International CFM56-5-A1 and -5-A1/F
HPTR front air seals, Part Number (P/N) 1319M11P06, 1319M11P07,
1319M11P08, and 1319M11P09, and CFM56-5-A1 HPTR front air seals, P/N
1319M11P05, and replace with a serviceable part, in accordance with
CFM56-5 Service Bulletin (SB) No. 72-541, dated July 27, 1998, as
follows:
(1) For seals that have accumulated less than 4,000 cycles since
new (CSN) on the effective date of this AD, remove the seal from
service prior to accumulating 11,000 CSN.
(2) For seals that have accumulated 4,000 CSN or more, but less
than 11,000 CSN on the effective date of this AD, accomplish the
following:
(i) For engines that have an engine shop visit (ESV) prior to
the seal accumulating 11,000 CSN, remove the seal from service prior
to the seal accumulating 11,000 CSN.
(ii) For engines that do not have an ESV prior to the seal
accumulating 11,000 CSN, remove the seal from service prior to the
seal accumulating 7,000 cycles in service (CIS) after the effective
date of this AD, or prior to the seal accumulating 15,300 CSN,
whichever occurs first.
(3) For seals that have accumulated 11,000 CSN or more on the
effective date of this AD, remove the seal from service at the next
ESV, or prior to the seal accumulating 15,300 CSN, whichever occurs
first.
(b) Remove from service CFM International CFM56-5A3 HPTR front
air seals, P/N 1319M11P06, 1319M11P07, 1319M11P08, and 1319M11P09,
and replace with a serviceable part, in accordance with CFM56-5 SB
No. 72-541, dated July 27, 1998, as follows:
(1) For seals that have accumulated less than 3,000 CSN on the
effective date of this AD, remove the seal from service prior to
accumulating 7,700 CSN.
(2) For seals that have accumulated 3,000 CSN or more, but less
than 7,700 CSN on the effective date of this AD, accomplish the
following:
(i) For engines that have an ESV prior to the seal accumulating
7,700 CSN, remove the seal from service prior to the seal
accumulating 7,700 CSN.
(ii) For engines that do not have an ESV prior to the seal
accumulating 7,700 CSN after the effective date of the AD, remove
the seal from service prior to the seal accumulating 4,700 CIS after
the effective date of this AD, or prior to the seal accumulating
13,000 CSN, whichever occurs first.
(3) For seals that have accumulated 7,700 CSN or more on the
effective date of this AD, remove the seal from service at the next
ESV, or prior to the seal accumulating 13,000 CSN, whichever occurs
first.
(c) For CFM56-5A4, -5A4/F, -5A5, and -5A5/F HPTR front air
seals, P/N 1319M11P05, 1319M11P06, 1319M11P07, 1319M11P08, and
1319M11P09, that have previously operated in CFM56-5-A1, -5-A1/F, or
-5A3 engine models, recalculate the HPTR front air seal total cycles
remaining using 11,000 cycles for the CFM56-5-A1 and CFM56-5-A1/F
engine models, and 7,700 cycles for the CFM56-5A3 engine model, in
accordance with CFM56-5 SB No. 72-541, dated July 27, 1998, within
750 CIS after the effective date of this AD.
Note 2: The current HPTR front air seal life for the CFM56-5A4,
-5A4/F, -5A5, and -5A5/F engine models is 9,100 cycles, and is not
affected by this AD.
Note 3: For additional information on recalculating the HPTR
front air seal total cycles remaining see Chapter 05, Section 05-11-
00, of the CFM56-5 series Engine Shop Manual, CFMI-TP.SM.7.
(d) This AD establishes new LCF retirement lives of 11,000
cycles for CFM56-
[[Page 49881]]
5-A1 and -5-A1/F HPTR front air seals, and 7,700 cycles for CFM56-
5A3 HPTR front air seals, which is published in Chapter 05, Section
05-11-03, of the CFM56-5 series Engine Shop Manual, CFMI-TP.SM.7.
The following conditions also apply:
(1) Except as provided in paragraph (g) of this AD, no
alternative retirement lives may be approved for the CFM56-5-A1, -5-
A1/F, and -5A3 HPTR front air seals.
(2) After the effective date of this AD, no CFM56-5-A1 and -5-
A1/F HPTR front air seals may be installed or reinstalled on an
engine if the seals have accumulated more than 11,000 CSN.
(3) After the effective date of this AD, no CFM56-5A3 HPTR front
air seals may be installed or reinstalled on an engine if the seals
have accumulated more than 7,700 CSN.
(e) For the purpose of this AD, an ``engine shop visit'' is
defined as the induction of an engine into the shop for maintenance
involving the separation of any major mating engine flanges, or the
removal of a disk or spool, except that the separation of engine
flanges solely for the purposes of transportation without subsequent
engine maintenance does not constitute an engine shop visit.
(f) For the purpose of this AD, a ``serviceable part'' is
defined as one that has not exceeded its respective new life limit
as set out in this AD.
(g) 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.
Operators shall submit their requests through an appropriate FAA
Principal Maintenance Inspector, who may add comments and then send
it to the Manager, Engine Certification Office.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
(h) 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 aircraft to a location where
the requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on September 11, 1998.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft
Certification Service.
[FR Doc. 98-25008 Filed 9-17-98; 8:45 am]
BILLING CODE 4910-13-P
