[Federal Register Volume 70, Number 169 (Thursday, September 1, 2005)]
[Proposed Rules]
[Pages 52043-52046]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-17400]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-18648; Directorate Identifier 2004-NE-26-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF34-1A, -3A, 
-3A1, -3A2, -3B, and -3B1 Series Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that was issued for General Electric Company (GE) CF34-
3A1 and -3B1 series turbofan engines with certain part numbers (P/Ns) 
and serial numbers (SNs) of stage 5 low pressure turbine (LPT) disks 
and stage 6 LPT disks. These engines are installed in Bombardier 
Canadair CL600-2B19 Regional Jet (RJ) airplanes. This proposed AD would 
add SNs to the affected disk population for RJ airplanes. This proposed 
AD would also add GE CF34-1 and -3 series turbofan engines with certain 
P/Ns and SNs of stage 5 LPT disks and stage 6 LPT disks, to the 
applicability section. These engines are installed in Bombardier 
Canadair models CL-600-2A12 (CL-601), CL-600-2B16 (CL-601-3A), (CL-601-
3R), and (CL-604) Business Jet (BJ) airplanes. This proposed AD would 
require initial and repetitive visual and eddy current inspections 
(ECI) of the affected disk population. This proposed AD would also 
allow replacement of those disks as optional terminating action to the 
repetitive inspections. Also, this proposed AD would require eventual 
replacement of the affected disks as terminating action to the 
repetitive inspections. This proposed AD results from the discovery of 
additional suspect stage 5 LPT disks and stage 6 LPT disks. These disks 
could fail due to low-cycle fatigue cracking that may start at the site 
of an electrical arc-out on the disk. We are proposing this AD to 
prevent low-cycle-fatigue (LCF) failure of stage 5 LPT disks and stage 
6 LPT disks, which could lead to uncontained engine failure.

DATES: We must receive any comments on this proposed AD by October 31, 
2005.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
    <bullet> DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
    <bullet> Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
    <bullet> Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, 
Washington, DC 20590-0001.
    <bullet> Fax: (202) 493-2251.
    <bullet> Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. 
Contact GE Aircraft Engines, 1000 Western Avenue, Lynn, MA 01910; 
Attention: CF34 Product Support Engineering, Mail Zone: 34017; 
telephone (781) 594-6323; fax (781) 594-0600, for the service 
information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT: Tara Fitzgerald, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7130; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-

[[Page 52044]]

2004-18648; Directorate Identifier 2004-NE-26-AD'' in the subject line 
of your comments. We specifically invite comments on the overall 
regulatory, economic, environmental, and energy aspects of the proposed 
AD. We will consider all comments received by the closing date and may 
amend the proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of the 
Docket Management System (DMS) Web site, anyone can find and read the 
comments in any of our dockets, including the name of the individual 
who sent the comment (or signed the comment on behalf of an 
association, business, labor union, etc.). You may review the DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the AD Docket

    You may examine the docket that contains the proposal, any comments 
received and any final disposition in person at the DMS Docket Offices 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Office (telephone (800) 647-5227) is located on 
the plaza level of the Department of Transportation Nassif Building at 
the street address stated in ADDRESSES. Comments will be available in 
the AD docket shortly after the DMS receives them.

Discussion

    On August 9, 2004, the FAA issued AD 2004-15-03R1, Amendment 39-
13773 (69 FR 50299, August 16, 2004). That AD requires initial and 
repetitive visual inspections and ECIs of certain SNs of stage 5 LPT 
disks, P/N 6078T92P01, and certain SNs of stage 6 LPT disks, P/N 
6078T89P01, installed in GE CF34-3A1 and -3B1 series turbofan engines 
that power certain Bombardier Canadair RJ airplanes. That AD also 
allows replacement of those SN disks as an optional terminating action 
to the repetitive inspections. Also, that AD requires replacement of 
certain stage 5 and stage 6 LPT disks. That AD was the result of an LCF 
failure of a stage 5 LPT disk that occurred during factory testing. GE 
performed a metallurgical evaluation of the disk. The evaluation showed 
that the origin of the LCF failure was a disk crack caused by 
inadvertent contact with electrochemical etch probes. These probes were 
used to match-mark components during engine assembly. GE's evaluation 
concluded that the probe contact caused damage known as electrical arc-
out. Electrical arc-out damage can lead to crack initiation and 
subsequent LCF failure of the disk. That AD also resulted from the 
discovery that an incorrect part number for stage 6 LPT disks was 
published in the existing AD and recognition of the need to allow 
credit for actions completed per previous releases of GE Alert Service 
Bulletin (ASB) No. CF34-AL S/B 72-A0173. That electrical arc-out damage 
condition, if not corrected, could result in LCF failure of stage 5 LPT 
disks and stage 6 LPT disks, and lead to uncontained engine failure.

Actions Since AD 2004-15-03R1 Was Issued

    Since we issued AD 2004-15-03R1, GE identified additional suspect 
stage 5 LPT disks, P/Ns 4922T16P01, 5024T53P01, 5024T53P02, and 
6078T92P01, and stage 6 LPT disks, P/Ns 4922T17P01, 5023T45P03, 
5023T45P04, and 6078T89P01, that might have the same arc-out 
indications. These disks are installed in GE CF34-1A, -3A, -3A1, -3A2, 
-3B, and -3B1 series turbofan engines that power Bombardier Canadair BJ 
and RJ airplanes. GE has issued ASBs to address these additional 
suspect disks.

Relevant Service Information

    We have reviewed and approved the technical contents of GE ASB No. 
CF34-AL S/B 72-A0173, Revision 05, dated May 24, 2005, and GE ASB No. 
CF34-BJ S/B 72-A0148, Revision 02, dated May 24, 2005. These SBs 
identify the suspect disks by serial number, and describe procedures 
for initial and repetitive visual inspections and ECIs and eventual 
replacement of those disks.

Differences Between the Proposed AD and the Manufacturer's Service 
Information

    GE ASB No. CF34-AL S/B 72-A0173, Revision 05, dated May 24, 2005, 
and GE ASB No. CF34-BJ S/B 72-A0148, Revision 02, dated May 24, 2005, 
require visually inspecting for electrical arc out indications around 
the match marks on stage 3 disk arms and stage 4 disk arms. This 
proposed AD would not mandate these inspections, as the stage 3 disks 
and stage 4 disks are not part of the suspect population.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other products 
of this same type design. For that reason, we are proposing this AD, 
which would require initial and repetitive visual inspections and ECIs 
of suspect disks and eventual replacement of those disks. The proposed 
AD would require that you do these actions using the service 
information described previously.

Costs of Compliance

    There are about 973 GE CF34-3A1 and -3B1 series turbofan engines 
installed in Bombardier Canadair RJ airplanes in the worldwide fleet 
and 683 of those engines are installed on airplanes of U.S. registry. 
We estimate that 355 of those engines would be affected by this 
proposed AD. There are about 970 CF34-1A, -3A, -3A1, -3A2, and -3B 
series turbofan engines installed in Bombardier Canadair BJ airplanes 
in the worldwide fleet and 690 of those engines are installed on 
airplanes of U.S. registry. We estimate that 249 of those engines would 
be affected by this proposed AD. We also estimate that it would take 
about 70 work hours per engine to perform the proposed disk inspections 
when the LPT module is exposed in the shop, and about 94 work hours per 
engine to perform the proposed disk inspections when the LPT module is 
forced off-wing. We also estimate that the average labor rate is $65 
per work hour. Prorated stage 5 LPT disks would cost about $42,650 
(RJ), and $71,083 (BJ) per engine and prorated stage 6 LPT disks would 
cost about $30,110 (RJ) and $50,183 (BJ) per engine. We also estimate 
that about 24 stage 5 LPT disks and about 24 stage 6 LPT disks would be 
found with the arc-out condition and require replacement. Based on 
these figures, we estimate the total cost of the proposed AD to U.S. 
operators to be $14,409,772.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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.
    For the reasons discussed above, I certify that the 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

[[Page 52045]]

    3. Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Under the authority delegated to me by the Administrator, the 
Federal Aviation Administration proposes to amend 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. The FAA amends Sec.  39.13 by removing Amendment 13773 (69 FR 
50299, August 16, 2004) and by adding a new airworthiness directive, 
Amendment 39-XXXXX, to read as follows:

General Electric Company: Docket No. FAA-2004-18648; Directorate 
Identifier 2004-NE-26-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by October 31, 
2005.

Affected ADs

    (b) This AD supersedes AD 2004-15-03R1, Amendment 39-13773.

Applicability

    (c) This AD applies to the following two groups of engine 
models:
    (1) General Electric Company (GE) CF34-3A1 and -3B1 series 
turbofan engines with stage 5 low pressure turbine (LPT) disks, part 
number (P/N) 6078T92P01 or stage 6 LPT disks P/N 6078T89P01, or 
both, with serial numbers (SNs) listed in Figure 3 or Figure 4 of GE 
Alert Service Bulletin (ASB) No. CF34-AL S/B 72-A0173, Revision 05, 
dated May 24, 2005. These engines are installed on Bombardier 
Canadair CL600-2B19 Regional Jet (RJ) airplanes.
    (2) GE CF34-1A, -3A, -3A1, -3A2, and -3B series turbofan engines 
with stage 5 LPT disks P/N 4922T16P01, 5024T53P01, 5024T53P02, or 
6078T92P01 or stage 6 LPT disks P/Ns 4922T17P01, 5023T45P03, 
5023T45P04, or 6078T89P01, or both, with SNs listed in Figure 3 or 
Figure 4 of GE ASB No. CF34-BJ S/B 72-A0148, Revision 02, dated May 
24, 2005. These engines are installed on Bombardier Canadair Models 
CL-600-2A12 (CL-601), CL-600-2B16 (CL-601-3A), (CL-601-3R), and (CL-
604) Business Jet (BJ) airplanes.

Unsafe Condition

    (d) This AD results from the discovery of an additional 
population of suspect stage 5 LPT disks and stage 6 LPT disks that 
could fail due to low-cycle fatigue cracking that may start at the 
site of an electrical arc-out on the disk.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified unless the 
actions have already been done.

Initial Inspection or Replacement

    (f) Using the compliance schedule in Table 1 of this AD, do the 
following:
    (1) For engines installed in Bombardier Canadair RJ airplanes, 
if a stage 5 LPT disk or stage 6 LPT disk listed in Figure 3 of GE 
ASB No. CF34-AL S/B 72-A0173, Revision 05, dated May 24, 2005 or 
listed in any previous issue of ASB No. CF34-AL S/B 72-A0173 did not 
complete a visual inspection and eddy current inspection (ECI) using 
paragraphs 3.C.(1) through 3.D.(2) and paragraphs 3.E. through 
3.E.(6) of the Accomplishment Instructions of that SB before June 1, 
2005, then replace that disk at the next piece-part exposure.

                      Table 1.--Compliance Schedule
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                                             Then perform the actions
                                           defined in paragraph (f) of
  On the effective date of this AD, if      this AD at next piece-part
             the disk has:                 exposure, not to exceed the
                                                 accumulation of:
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(i) 14,750 or more cycles-since-new      An additional 250 cycles-in-
 (CSN) and has not been fluorescent       service (CIS) after the
 penetrant inspected (FPI) at an          effective date of this AD
 earlier piece-part exposure.
(ii) 14,750 or more CSN and has been     An additional 500 CIS after the
 FPI at an earlier piece-part exposure..  effective date of this AD
(iii) 14,500 or more CSN but fewer than  An additional 500 CIS after the
 14,750 CSN.                              effective date of this AD.
(iv) 14,250 or more CSN but fewer than   An additional 750 CIS after the
 14,500 CSN.                              effective date of this AD.
(v) 13,000 or more CSN but fewer than    An additional 1,000 CIS after
 14,250 CSN.                              the effective date of this AD.
(vi) 2,500 or more CSN but fewer than    An additional 4,000 CIS after
 13,000 CSN.                              the effective date of this AD,
                                          or 14,000 CSN, whichever comes
                                          first.
(vii) Fewer than 2,500 cycles-since-new  6,500 CSN.
 (CSN).
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    (2) For engines installed in Bombardier Canadair BJ airplanes, 
perform an initial visual inspection and ECI of stage 5 LPT disks 
and stage 6 LPT disks listed in Figure 3 of GE ASB No. CF34-BJ S/B 
72-A0148, Revision 02, dated May 24, 2005, before January 1, 2010. 
Use paragraphs 3.C.(1) through 3.D.(2) and paragraphs 3.E. through 
3.E.(6) of Accomplishment Instructions of GE ASB No. CF34-BJ S/B 72-
A0148, Revision 02, dated May 24, 2005 to do the inspections.

Repetitive Inspections

    (g) For engines installed in Bombardier Canadair RJ airplanes 
with stage 5 LPT disks and stage 6 LPT disks listed in Figure 3 of 
GE ASB No. CF34-AL S/B 72-A0173, Revision 05, dated May 24, 2005, 
that were initially visually inspected and ECI'ed before June 1, 
2005, do the following:
    (1) Perform repetitive visual inspections and ECIs within every 
3,100 cycles-since-last-inspection (CSLI), until the life limit of 
the disk is reached.
    (2) Use paragraphs 3.C.(1) through 3.D.(2) and paragraphs 3.E. 
through 3.E.(6) of Accomplishment Instructions of GE ASB No. CF34-AL 
S/B 72-A0173, Revision 05, dated May 24, 2005 to do the inspections.
    (h) For engines installed in Bombardier Canadair BJ airplanes, 
with stage 5 LPT disks and stage 6 LPT disks initially inspected as 
specified in paragraph (f)(2) of this AD, do the following:
    (1) Perform repetitive visual inspections and ECIs within every 
3,100
    CSLI, until the life limit of the disk is reached.
    (2) Use paragraphs 3.C.(1) through 3.D.(2) and paragraphs 3.E. 
through 3.E.(6) of Accomplishment Instructions of GE ASB No. CF34-BJ 
S/B 72-A0148, Revision 02, dated May 24, 2005, to do the 
inspections.

Disks That Pass Inspection

    (i) Reinstall disks that pass the inspections in paragraphs (f), 
(g), and (h) of this AD into the same LPT module from which they 
were removed.

LPT Stage 5 and Stage 6 Disk Removal

    (j) Remove any disk from service if there is an arc-out found on 
that disk.
    (k) At the next piece-part exposure for engines installed in 
Bombardier Canadair RJ airplanes, remove from service stage 5 LPT 
disks and stage 6 LPT disks listed in Figure 4 of GE ASB No. CF34-AL 
S/B 72-A0173, Revision 05, dated May 24, 2005.
    (l) At the next piece-part exposure for engines installed in 
Bombardier Canadair BJ

[[Page 52046]]

airplanes, remove from service stage 5 LPT disks and stage 6 LPT 
disks listed in Figure 4 of GE ASB No. CF34-BJ S/B 72-A0148 Revision 
02, dated May 24, 2005.

Optional Terminating Action

    (m) Replacement of an affected stage 5 LPT disk or affected 
stage 6 LPT disk, with a disk not listed in Figure 3 or Figure 4 of 
GE ASB No. CF34-AL S/B 72-A0173 Revision 05, dated May 24, 2005 or 
not listed in Figure 3 or Figure 4 of GE ASB No. CF34-BJ S/B 72-
A0148, Revision 02, dated May 24, 2005 is terminating action to the 
repetitive inspections and removals required by this AD for that 
disk.

Terminating Action

    (n) As terminating action to the repetitive inspections and 
removals in this AD, replace all disks by January 1, 2013 that are 
listed in Figure 3 and Figure 4 of GE ASB No. CF34-AL S/B 72-A0173, 
Revision 05, dated May 24, 2005, and that are listed in Figure 3 and 
Figure 4 of GE ASB No. CF34-BJ 72-A0148, Revision 02, dated May 24, 
2005.

Actions Completed Per Previous Releases of Alert Service Bulletins

    (o) Actions completed before the effective date of this AD using 
GE ASB No. CF34-AL S/B 72-A0173, dated April 2, 2004; or Revision 
01, dated May 20, 2004; or Revision 02, dated June 22, 2004; or 
Revision 03, dated July 20, 2004; or Revision 04, dated February 7, 
2005; or GE ASB No. CF34-BJ S/B 72-A0148, dated September 2, 2004; 
or Revision 01, dated March 10, 2005, are considered acceptable for 
compliance with the corresponding action in this AD.

Serviceable LPT Disk Definition

    (p) For the purpose of this AD, a serviceable LPT disk is a disk 
not listed in Figure 3 or Figure 4 of GE ASB No. CF34-AL S/B 72-
A0173 Revision 05, dated May 24, 2005, or Figure 3 or Figure 4 of GE 
ASB No. CF34-BJ 72-A0148, Revision 02, dated May 24, 2005.

Piece-Part Exposure Definitions

    (q) For the purpose of this AD, the definition of piece part 
exposure for the stage 5 LPT disk is when the disk is separated from 
the forward and aft bolted joints.
    (r) For the purpose of this AD, the definition of piece part 
exposure for the stage 6 LPT disk is when the disk is separated from 
the forward bolted joint.

Replacement Engine or Replacement LPT Module Definition

    (s) For the purpose of this AD, the definition of a replacement 
engine or replacement LPT module is an engine or LPT module that 
does not have installed any of the suspect disks listed in Figure 3 
or Figure 4 of GE ASB No. CF34-AL S/B 72-A0173 Revision 05, dated 
May 24, 2005, or Figure 3 or Figure 4 of GE ASB No. CF34-BJ 72-
A0148, Revision 02, dated May 24, 2005.

Alternative Methods of Compliance

    (t) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (u) GE ASB No. CF34-AL S/B 72-A0178 and ASB No. CF34-BJ S/B 72-
A0152 contain the information necessary to identify and inspect the 
suspect disks that are the subject of this AD.

    Issued in Burlington, Massachusetts, on August 26, 2005.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 05-17400 Filed 8-31-05; 8:45 am]
BILLING CODE 4910-13-P