CF34 Engines Winter 2007

• GE AD Note 2006-04-12, SB 72-A0148, SB 72-A0152, LPT Stages 5 & 6 disk arc out inspection and replace

GE AD Note 2006-04-12, SB 72-A0148, SB 72-A0152, LPT Stages 5 & 6 disk arc out inspection and replace

There are approximately 150 weeks to do 900 engines, six engines per week need to be complied with.

There are currently 900 CF34 engines affected by Airworthiness Directive (AD) 2006-04-12. GE Service Bulletin 72-A0148, addresses removal, disassembly, inspection for arc out, reassembly and reinstallation of the LPT stage 5 & 6 turbine disks. This inspection must be complied with at an overhaul shop by January 1, 2010.

GE SB 72-A0152 addresses the replacement of the stage 5 & 6 LPT disk, which must be completed by January 1, 2013.

GE recommends the replacement of the LPT stage 5 & 6 disks by the January, 1, 2010 date, to prevent removing the LPT modules twice. This also eliminates the possibility of extending aircraft downtime due to detailed inspection procedures.

If the LPT stage 5 & 6 disks are replaced by January 1, 2010, GE will allow a pro-rata discount, up to 75%, of GE catalog price for any unused cycles and 90 man-hours of labor to perform the replacement. GE SB 72-A0200, inspection of the LPT cases at 3:00 and 9:00 o'clock position for cracks is accomplished during the disassembly of the LPT modules. GE SB 72-0202, applies to GE CF34-3B engines and introduces a new/reworked low pressure turbine (LPT) stage 3 shroud sector (PN 5099T32G02) with an improved integral heat-shield. The new stage 3 shroud sector design eliminates the heat-shield end gap, which has led to LPT case cracking. GE recommends that this SB be complied with as soon as the LPT is removed from the engine.

Duncan Aviation recommends complying with these Service Bulletins and AD in conjunction with other maintenance, allowing three weeks downtime to get the engine work accomplished. Our engine technicians can remove the LPT modules from the engines and ship them to the overhaul shop of your choice. After the LPT modules are returned from the overhaul shop, we can reinstall them and return the engines back to service.

Duncan Aviation also recommends compliance with SB 72-0093, # 5 bearing rotating air seal, if required on your engine. We can accomplish SB 72-0093 in-house. Complying with SB 72-0093 replacing the # 5 bearing rotating air seal satisfies the requirements of AD Note 2001-12-06 reoccurring chip detector inspections.

Information and excerpts for this article were taken from the AD Note 2006-04-12, SB 72-A0148, SB 72-A0152 and CF34 Engine Topic-CF34-07-2006.

For more information regarding the above and other Airworthy Directives or Service Bulletins, contact your Duncan Aviation CF34 experts at either of our full service facilities.

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