[Federal Register Volume 65, Number 161 (Friday, August 18, 2000)]
[Proposed Rules]
[Pages 50468-50470]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-21054]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NE-49-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF34 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of Proposed Rule Making; Revision.

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SUMMARY: This document proposes to revise an existing airworthiness 
directive (AD), applicable to General Electric Company CF34 series 
turbofan engines. That AD currently requires revisions to the Engine 
Maintenance Program specified in the manufacturer's Instructions for 
Continued Airworthiness (ICA) for General Electric Company (GE) CF34 
series turbofan engines. Those revisions require enhanced inspection of 
selected critical life-limited parts at each piece-part exposure. That 
AD also requires that an air carrier's approved continuous 
airworthiness maintenance program incorporate these inspection 
procedures. This action would require the removal of certain inspection 
requirements for parts removed from engines mounted on-wing. This 
proposal is prompted by the high removal rate and subsequent piece-part 
exposure of fan disks due to certain mandatory maintenance procedures. 
This additional exposure has resulted in fan disk focused inspection 
rates that exceed the intent of the focused inspection initiative.

DATES: Comments for inclusion in the Rules Docket must be received on 
or before September 18, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 99-NE-49-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299. Comments may also be sent via the Internet 
using the following address: ``[email protected]''. Comments sent 
via the Internet must contain the docket number in the subject line.

FOR FURTHER INFORMATION CONTACT: Kevin Donovan, Aerospace Engineer 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7743, fax (238) 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 99-NE-44-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. 99-NE-44-AD, 12 New England Executive Park, 
Burlington, MA 01803-5299.

[[Page 50469]]

Discussion

    On February 7, 2000, the FAA issued AD 2000-03-03, Amendment 39-
11560, (65 FR 5759) to require changes to the Engine Maintenance 
Program specified in the manufacturer's ICA for GE CF34 series turbofan 
engines. These changes required enhanced inspection of selected 
critical life-limited parts at each piece-part exposure and that an air 
carrier's approved continuous airworthiness maintenance program 
incorporate these inspection procedures. That action was prompted by an 
FAA study of in-service events involving uncontained failures of 
critical rotating engine parts, which indicated the need for improved 
inspections. The improved inspections are needed to identify those 
critical rotating parts with conditions that, if allowed to continue in 
service, could result in uncontained failures. If not corrected, that 
condition could result in engine rotating part failure, which could 
result in an uncontained engine failure and damage to the airplane.

Revised Inspection Requirements

    Since AD 2000-03-03 was issued, the FAA has determined that, for 
piece-part exposures resulting from parts removed from an engine 
mounted on-wing in accordance with certain maintenance procedures, it 
is unnecessary to perform the inspection requirements listed in Table 
804 of the GE CF34 series turbofan Engine Manual. Performing the 
enhanced inspections each time the disk is exposed on-wing does not 
significantly add to the probability of detection of defects. The FAA 
has concluded that inspection at every opportunity for this model 
engine is not necessary to maintain the level of safety intended by the 
current AD.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other GE CF34 engines of the same type design, the 
proposed AD would revise AD 2000-03-03 to change the mandatory 
inspection requirements to relieve parts removed from engines mounted 
on-wing from the inspection requirements of Table 804.

Regulatory Impact

    The proposed revision would not increase the economic burden on US 
operators as set out in the economic analysis published for the current 
AD.
    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    The FAA has determined that this regulation is not a ``significant 
regulatory action'' under Executive Order 12866. It has been determined 
further that this action involves an emergency regulation under DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If 
it is determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from 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 removing Amendment 39-11560 (65 FR 
5759, February 7, 2000), and by adding a new airworthiness directive, 
to read as follows:

General Electric Company: Docket 99-NE-49 AD. Revises AD 2000-03-03, 
Amendment 39-11560.

    Applicability: General Electric Company (GE) CF34-3A1 and -3B1 
series turbofan engines, installed on but not limited to Bombardier 
Canadair CL601R (RJ) aircraft.

    Note 1: This 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 critical life-limited rotating engine part failure, 
which could result in an uncontained engine failure and damage to 
the airplane, accomplish the following:

Inspections

    (a) Within the next 30 days after the effective date of this AD, 
revise the CF34 Engine Maintenance Program, Chapter 5-21-00, of the 
GE CF34 Series Turbofan Engine Manual, SEI-756, and for air carrier 
operations revise the approved continuous airworthiness maintenance 
program, by adding the following:
    ``9. CF34-3A1 and CF34-3B1 Engine Maintenance Program --
Mandatory Inspection Requirements.
    (A) This procedure is used to identify specific piece-parts that 
require mandatory inspections that must be accomplished at each 
piece-part exposure using the applicable Chapters referenced in 
Table 804 for the inspection requirements. The inspection 
requirements listed in Table 804 are not required for any piece-part 
exposure resulting when the engine remains on-wing while performing 
maintenance practice, special procedure Number 41 listed in SEI-756, 
chapter 72-00-00, or from Alert Service Bulletin 72-A0103__R00.
    (B) Piece-part exposure is defined as follows: Note: Fan disk 
piece-part includes the fan disk with the 56 fan pin bushings 
installed.
    (1) For engines that utilize the ``On Condition'' maintenance 
requirements: The part is considered completely disassembled to the 
piece-part level when done in accordance with the disassembly 
instructions in the GEAE authorized overhaul Engine Manual, and the 
part has accumulated more than 100 cycles-in-service since the last 
piece-part opportunity inspection, provided that the part was not 
damaged or related to the cause for its removal from the engine.
    (2) For engines that utilize the ``Hard Time'' maintenance 
requirements: The part is considered completely disassembled when 
done in accordance with the disassembly instructions used in the 
``Minor Maintenance'' or ``Overhaul'' instructions in the GEAE 
engine authorized Engine Manual, and the part has accumulated more 
than 100 cycles in service since the last piece-part opportunity 
inspection, provided that the part was not damaged or related to the 
cause for its removal from the engine.
    C. Refer to Table 804 below for the mandatory inspection 
requirements.

[[Page 50470]]



                                  Table 804.--Mandatory Inspection Requirements
----------------------------------------------------------------------------------------------------------------
                                             Manual/chapter, section/
            Part nomenclature                         subject                     Mandatory, inspection
----------------------------------------------------------------------------------------------------------------
Fan Disk (all)...........................  72-21-00, INSPECTION........  All areas (FPI) \1\
                                                                         Bores (ECI) \2\
Stage 1 high pressure turbine (HPT) Rotor  72-46-00, INSPECTION........  All areas
 Disk (all) (FPI)\1\.                                                    Bores (ECI) \2\
                                                                         Boltholes (ECI) \2\
                                                                         Air Holes (ECI) \2\
Stage 2 HPT Rotor Disk (all).............  72-46-00, INSPECTION........  All Areas (FPI) \1\
                                                                         Bores (ECI) \2\
(a) Boltless Rim Configuration...........  ............................  Boltholes (FPI) \1\
                                                                         Air Holes (FPI) \1\
(b) Bolted Rim Configuration.............  ............................  Boltholes (ECI) \2\
                                                                         Air Holes (ECI) \2\
HPT Rotor Outer Torque Coupling (all)....  72-46-00, INSPECTION........  All areas (FPI) \1\
                                                                         Bore (ECI) \2\
----------------------------------------------------------------------------------------------------------------
\1\ FPI=Fluorescent Penetrant Inspection Method
\2\ ECI=Eddy Current Inspection

    (b) Except as provided in paragraph (c) of this AD, and 
notwithstanding the provisions of section 43.16 of the Federal 
Aviation Regulations (14 CFR 43.16), these mandatory inspections 
shall be performed only in accordance with the CF34 Engine 
Maintenance Program, Chapter 5-21-00, of the General Electric 
Company, CF34 Series Turbofan Engine Manual, SEI-756.

Alternative Method of Compliance

    (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 (ECO). 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector (PMI), who may add comments and then 
send it to the Manager, ECO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the ECO.

Special Flight Permits

    (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 airplane to a location where 
the requirements of this AD can be accomplished.

Continuous Airworthiness Maintenance Program

    (e) FAA-certificated air carriers that have an approved 
continuous airworthiness maintenance program in accordance with the 
record keeping requirement of Sec. 121.369(c) of the Federal 
Aviation Regulations [14 CFR 121.369(c)] must maintain records of 
the mandatory inspections that result from revising the CF34 Engine 
Maintenance Program and the air carrier's continuous airworthiness 
program. Alternately, certificated air carriers may establish an 
approved system of record retention that provides a method for 
preservation and retrieval of the maintenance records that include 
the inspections resulting from this AD, and include the policy and 
procedures for implementing this alternate method in the air 
carrier's maintenance manual required by Sec. 121.369(c) of the 
Federal Aviation Regulations [14 CFR 121.369(c)]; however, the 
alternate system must be accepted by the appropriate PMI and require 
the maintenance records be maintained either indefinitely or until 
the work is repeated. Records of the piece-part inspections are not 
required under 121.380(a)(2)(vi) of the Federal Aviation Regulations 
[14 CFR 121.380(a)(2)(vi)]. All other operators must maintain the 
records of mandatory inspections required by the applicable 
regulations governing their operations.

    Note 3: The requirements of this AD have been met when the 
engine manual changes are made and air carriers have modified their 
continuous airworthiness maintenance plans to reflect the Engine 
Maintenance Program requirements specified in the GE CF34 Series 
Turbofan Engine Manual.


    Issued in Burlington, Massachusetts, on August 11, 2000.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-21054 Filed 8-17-00; 8:45 am]
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