AD 2006-04-12 Airworthiness Directives; General Electric Company CF34-1A, -3A, -3A1, -3A2, -3B, and -3B1 Series Turbofan Engines

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.

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. Stage 5 and Stage 6 LPT 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 S/B 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 S/B 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 S/B 72-A0148, Revision 02, dated May 24, 2005. Alternative Methods of

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. We are issuing 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.