05-17400. 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).

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.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
• Fax: [phone].
• 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 [phone]; fax [phone], 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 [phone]; fax [phone].

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-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 [phone]) 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

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.

§ 39.13

[Amended]

2. The FAA amends § 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

On the effective date of this AD, if the disk has:	Then perform the actions defined in paragraph (f) of this AD at next piece-part exposure, not to exceed the accumulation of:
(i) 14,750 or more cycles-since-new (CSN) and has not been fluorescent penetrant inspected (FPI) at an earlier piece-part exposure	An additional 250 cycles-in-service (CIS) after the effective date of this AD
(ii) 14,750 or more CSN and has been FPI at an earlier piece-part exposure.	An additional 500 CIS after the effective date of this AD
(iii) 14,500 or more CSN but fewer than 14,750 CSN	An additional 500 CIS after the effective date of this AD.
(iv) 14,250 or more CSN but fewer than 14,500 CSN	An additional 750 CIS after the effective date of this AD.
(v) 13,000 or more CSN but fewer than 14,250 CSN	An additional 1,000 CIS after the effective date of this AD.
(vi) 2,500 or more CSN but fewer than 13,000 CSN	An additional 4,000 CIS after the effective date of this AD, or 14,000 CSN, whichever comes first.
(vii) Fewer than 2,500 cycles-since-new (CSN)	6,500 CSN.

(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 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.