[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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