[Federal Register Volume 60, Number 242 (Monday, December 18, 1995)]
[Proposed Rules]
[Pages 65035-65036]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30645]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-ANE-41]


Airworthiness Directives; General Electric Company CF34 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 General Electric Company (GE) CF34 
series turbofan engines. This proposal would reduce the allowable 
operating cyclic life limit for affected high pressure compressor (HPC) 
stage 1 rotor disks. This proposal is prompted by an updated stress and 
life analysis. The actions specified by the proposed AD are intended to 
prevent HPC stage 1 rotor disk rupture, engine failure, and damage to 
the aircraft.

DATES: Comments must be received by February 16, 1996.

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-41, 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: Eugene Triozzi, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7148, 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-41.'' 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-41, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has reviewed and approved 
an updated stress and life analysis for high pressure compressor (HPC) 
stage 1 rotor disks installed in General Electric Company (GE) CF34 
series turbofan engines. Although the FAA has not received any reports 
of cracked or failed HPC stage 1 rotor disks, the stress and life 
analysis was performed using new, improved methodology. This analysis 
revealed that the published cyclic life limits were higher than updated 
calculated lives, which could result in the operation of an HPC stage 1 
rotor disk beyond its cyclic life. This condition, if not corrected, 
could result in HPC stage 1 rotor disk rupture, 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 reduce the allowable operating cyclic life limit for 
affected HPC stage 1 rotor disks.
    There are approximately 440 engines of the affected design in the 
worldwide fleet. The FAA estimates that 150 engines installed on 
aircraft of U.S. registry would be affected by this 

[[Page 65036]]
proposed AD, that it would take zero additional work hours per engine 
to accomplish the proposed actions, and that the average labor rate is 
$60 per work hour. Required parts would cost approximately $7,667 per 
engine, based on the estimated current part cost, prorated downward by 
a factor equal to the quotient of the difference between the original 
cyclic life limit (9000 cycles) and the revised cyclic life limit (6000 
cycles) divided by the original cyclic life limit. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $1,150,000.
    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), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

General Electric Company: Docket No. 95-ANE-41.

    Applicability: General Electric Company (GE) Models CF34-1A, -
3A, and -3A2 turbofan engines, with high pressure compressor (HPC) 
stage 1 rotor disks, part number 6040T79G01, installed. These 
engines are installed on but not limited to Canadair Limited Model 
CL-600-2A12 and CL-600-2B16 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 (b) 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 HPC stage 1 rotor disk rupture, engine failure, and 
damage to the aircraft, accomplish the following:
    (a) Remove from service HPC stage 1 rotor disks prior to 
accumulating 6,000 cycles in service since new, and replace with a 
serviceable part.
    (b) 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.

    Issued in Burlington, Massachusetts, on December 8, 1995.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 95-30645 Filed 12-15-95; 8:45 am]
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