[Federal Register Volume 63, Number 181 (Friday, September 18, 1998)]
[Proposed Rules]
[Pages 49877-49879]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-25009]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-ANE-19-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Aircraft Engines 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 Aircraft Engines 
(GE) CF34 series turbofan engines. This proposal would require rework 
of the main fuel control (MFC) to add a flange vent groove and 
installation of a reworked MFC with improved overspeed protection. This 
proposal is prompted by reports of rapid uncommanded engine 
acceleration events. The actions specified by the proposed AD are 
intended to prevent uncommanded engine accelerations, which could 
result in an engine overspeed, uncontained engine failure, and damage 
to the aircraft.

DATES: Comments must be received by November 17, 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-19-AD, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may also be sent 
via the Internet using the following address: ``9-ad-
[email protected]''. 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 GEAE Technical Publications, Attention: N. Hanna MZ340M2, 
1000 Western Avenue, Lynn, MA. 01910. 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: Norman Brown, Controls Specialist, 
Engine Certification Office, ANE-141, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (781) 238-7129, 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

[[Page 49878]]

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-19-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-19-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    The Federal Aviation Administration (FAA) has received reports of 
rapid uncommanded engine acceleration events on certain General 
Electric Aircraft Engines (GE) CF34-3A1, CF34-3B and CF34-3B1 series 
turbofan engines. Subsequent investigations have revealed that fuel 
seepage may become trapped between the main fuel control (MFC) and the 
main fuel pump flanges, resulting in an uncommanded engine 
acceleration, and also preventing a portion of the engine overspeed 
protection system from properly functioning. Under specific conditions, 
the trapped fuel can lead to an overspeed condition of sufficient 
severity to cause uncontained rotor failure. In addition, all GE CF34 
series MFCs contain a feature that prevents a portion of the overspeed 
protection system, called the cutback schedule, from performing its 
intended function. The cutback schedule allows a rapid reduction in 
fuel flow in the event of increasing engine speed due to acceleration 
above the overspeed cutoff region. This feature can similarly permit an 
uncommanded engine acceleration to result in an overspeed and 
uncontained rotor failure. This condition, if not corrected, could 
result uncontained engine failure, and damage to the aircraft.
    The FAA has reviewed and approved the technical contents of GE CF34 
Alert Service Bulletin (ASB) No. A73-18, Revision 1, dated September 
24, 1997, and CF34 ASB No. A73-32, Revision 1, dated September 24, 
1997, that describe procedures for reworking MFCs by adding a flange 
vent groove; and CF34 ASB No. A73-33, dated November 21, 1997, and CF34 
ASB No. A73-19, Revision 1, dated February 20, 1998, that describe 
procedures for installation of a reworked MFC with improved overspeed 
protection.
    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, within 800 hours time in service (TIS), or 
120 days after the effective date of this AD, whichever occurs first, 
installation of a reworked MFC incorporating a flange vent groove. In 
addition, this proposed AD would require installation of a reworked MFC 
with improved overspeed protection: for CF34-3A1 and -3B1 series 
engines, installed on Canadair Regional Jet aircraft, within 4,000 
hours TIS after the effective date of this AD, or 24 months after the 
effective date of this AD, whichever occurs first; and for CF34-1A, -
3A, 3A1, -3A2, and -3B series engines, installed on Canadair Challenger 
aircraft, at the next hot section inspection, or 5 years after the 
effective date of this AD, whichever occurs first. The different 
calendar times were determined based upon engine utilization rates 
during Regional Jet and Challenger aircraft operation, and based upon 
shop and parts availability. The actions would be required to be 
accomplished in accordance with the SBs described previously.
    There are approximately 1,310 engines of the affected design in the 
worldwide fleet. The FAA estimates that 450 engines installed on 
aircraft of U.S. registry would be affected by this proposed AD, that 
it would take approximately 21 work hours per engine to accomplish the 
proposed actions, and that 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 $567,000. The manufacturer has 
advised the FAA that labor allowances may be provided.
    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:

General Electric Aircraft Engines: Docket No. 98-ANE-19-AD.

    Applicability: General Electric Aircraft Engines (GE) CF34-1A, 
CF34-3A, -3A1, -3A2, and CF34-3B and -3B1 series turbofan engines, 
installed on but not limited to Canadair aircraft models CL-600-
2A12, -2B16, and -2B19.

    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 uncommanded engine accelerations, which could result 
in an engine overspeed, uncontained engine failure, and damage to 
the aircraft, accomplish the following:
    (a) For all CF34-3A1 -3B, and -3B1 engines, with main fuel 
control (MFC) part

[[Page 49879]]

number 6078T55P02, P03, P04, P05, P06, P07, P08, P09, or P10 
installed, within 800 hours time in service (TIS), or 120 days after 
the effective date of this AD, whichever occurs first, install an 
MFC with a flange vent groove reworked in accordance with the 
Accomplishment Instructions of GE CF34 Alert Service Bulletin (ASB) 
No. A73-18, Revision 1, dated September 24, 1997, or CF34 ASB No. 
A73-32, Revision 1, dated September 24, 1997, as applicable.
    (b) Install a reworked MFC with improved overspeed protection as 
follows:
    (1) For all CF34-1A, -3A, and -3A2, series engines, install MFC 
part number 6047T74P11, 6047T74P12, or 6091T07P02, at the next hot 
section inspection, or 60 months after the effective date of this 
AD, whichever occurs first, in accordance with the Accomplishment 
Instructions of GE CF34 ASB No. A73-33, dated November 21, 1997.
    (2) For CF34-3A1, and -3B series engines, installed on Canadair 
aircraft models CL601 or CL604 (Challenger aircraft), install MFC 
part number 6078T55P12, 6078T55P13, 6078T55P14, 6078T55P15, or 
6078T55P16, at the next hot section inspection, or 60 months after 
the effective date of this AD, whichever occurs first, in accordance 
with the Accomplishment Instructions of GE CF34 ASB No. A73-33, 
dated November 21, 1997.
    (3) For CF34-3A1 and -3B1 series engines, installed on Canadair 
aircraft model CL601R (Regional Jet aircraft), install MFC part 
number 6078T55P12, 6078T55P13, 6078T55P14, 6078T55P15, or 
6078T55P16, within 4,000 hours TIS after the effective date of this 
AD, or 24 months after the effective date of this AD, whichever 
occurs first, in accordance with the Accomplishment Instructions of 
GE CF34 ASB No. A73-19, Revision 1, dated February 20, 1998.
    (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 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 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 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. 98-25009 Filed 9-17-98; 8:45 am]
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