[Federal Register Volume 60, Number 195 (Tuesday, October 10, 1995)]
[Proposed Rules]
[Pages 52636-52637]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25033]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 95-ANE-44]
Airworthiness Directives; CFM International CFM56-3C 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 (CFMI) CFM56-3C
series turbofan engines. This proposal would require a reduction of the
low cycle fatigue (LCF) retirement lives for certain fan disks. This
proposal is prompted by the results of a refined life analysis
performed by the manufacturer which revealed minimum calculated LCF
lives significantly lower than published LCF retirement lives. The
actions specified by the proposed AD are intended to prevent a LCF
failure of the fan disk, which could result in an uncontained engine
failure and damage to the aircraft.
DATES: Comments must be received by December 11, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), New England Region, Office of the Assistant Chief
Counsel, Attention: Rules Docket No. 95-ANE-44, 12 New England
Executive Park, Burlington, MA 01803-5299. 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: Robert J. Ganley, Aerospace Engineer,
Engine Certification Office, FAA, Engine and Propeller Directorate, 12
New England Executive Park, Burlington, MA 01803-5299; telephone (617)
238-7138; fax (617) 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 95-ANE-44.'' 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 Assistant Chief Counsel,
Attention: Rules Docket No. 95-ANE-44, 12 New England Executive Park,
Burlington, MA 01803-5299.
Discussion
This proposed airworthiness directive (AD) is applicable to CFM
International (CFMI) CFM56-3C series turbofan engines. A study
performed by the manufacturer using updated lifing analyses revealed
that certain fan disks have minimum calculated low cycle fatigue (LCF)
lives which are significantly lower than published LCF retirement
lives. This condition, if not corrected, could result in a LCF failure
of the fan disk, which could result in an uncontained engine failure
and damage to the aircraft.
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 require a reduction of the LCF retirement lives for
certain fan disks.
The FAA estimates that 33 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 $17,275 per engine. Based on these figures, the total
cost impact of the proposed AD on U.S. operators is estimated to be
$570,075.
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,
[[Page 52637]]
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 USC 106(g), 40101, 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
CFM International: Docket No. 95-ANE-44.
Applicability: CFM International (CFMI) CFM56-3C series turbofan
engines installed on, but not limited to Boeing 737 series aircraft.
Note: 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 use the
authority provided in paragraph (d) to request approval from the
Federal Aviation Administration (FAA). This approval may address
either no action, if the current configuration eliminates the unsafe
condition, or different actions necessary to address the unsafe
condition described in this AD. Such a request should include an
assessment of the effect of the changed configuration on the unsafe
condition addressed by this AD. In no case does the presence of any
modification, alteration, or repair remove any engine from the
applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent a low cycle fatigue (LCF) failure of the fan disk,
which could result in an uncontained engine failure and damage to
the aircraft, accomplish the following:
(a) Remove from service CFM56-3C fan disks, Part Numbers 335-
014-509-0 and 335-014-511-0, prior to accumulating the equivalent of
20,100 cycles at the Category C thrust rating.
(b) This action establishes the new LCF retirement life of
20,100 cycles noted in paragraph (a) of this AD, which is published
in Chapter 05 of CFM56 Engine Shop Manual, CFMI-TP.SM.5.
(c) For the purpose of this AD, Category C thrust rating is
defined as operation at CFM56-3C-1 engine nameplate model thrust
levels.
(d) 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. The
request should be forwarded through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Engine Certification Office.
Note: Information concerning the existence of approved
alternative methods of compliance with this airworthiness directive,
if any, may be obtained from the Engine Certification Office.
(e) 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 aircraft to a location where the
requirements of this AD can be accomplished.
Issued in Burlington, Massachusetts, on September 27, 1995.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification
Service.
[FR Doc. 95-25033 Filed 10-6-95; 8:45 am]
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