[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]
=======================================================================
-----------------------------------------------------------------------
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).
-----------------------------------------------------------------------
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: ``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 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]
BILLING CODE 4910-13-P
