In April the FAA issued an awaited airworthiness directive (AD) on Pratt & Whitney Canada Corp. PT6A-34, -34B, -34AG, -114 and -114A model turboprop engines. The AD requires the following actions to be taken within 250 flight hours or 270 days after the effective date of May 27, 2022, whichever occurs first:
- Remove from service any CT vane, part number (P/N) 3029051, 3032151 or 3123001, repaired in accordance with Southwest Turbine Inc. (STI) Repair Specification STI 72-50-254 (STI 72-50-254) and replace with a non-STI 72-50-254 repaired CT vane.
- Remove from service any CMSX-6 CT blade that has been operated on an affected engine with any CT vane repaired in accordance with STI 72-50-254.
The FAA first proposed this AD in August of 2020. To read the complete AD, click here. The FAA estimates that this AD affects 907 engines installed on airplanes of U.S. registry. The FAA estimates that 63 engines will need to replace the CT vanes and CT blades. The FAA received comments from 13 commenters. The comments and the FAA’s responses may be viewed at the previous link.
The following information is from:
Robert Craymer
robertc@covingtonaircraft.com
(662) 910-9899
and
Fletcher Sharp
fletchers@covingtonaircraft.com
(214) 766-1212
Compressor Turbine Vane Rings (CTVR) that are affected by the AD: Part numbers 3029051, 3032151 and 3123001 that have been repaired in accordance with repair process STI 72-50-254. This is a specific repair process performed by Southwest Turbine Inc. Part number vanes repaired by specific repair STI 72-50-254 are the only ones affected by this AD.
How to determine if your engine is affected:
Review your engine logbooks. There should be entries for hot section inspections and/or CT vane replacement. One may also have 8130-3 forms from the CTVRs that have been installed. If you find any of the above-mentioned CTVR part numbers that have been repaired in accordance with the referenced repair process, then your engine is affected. In addition, if your engine has CMSX-6 blades (single crystal blades), then the blades will require replacement.
If you know a vane replacement has occurred but the logbook doesn’t contain complete data or an 8130-3 to identify the CTVR or how it was repaired, the only way to verify if your CTVR is affected is to split the engine and complete a review of the CTVR. You can also contact your local mechanic who performed your last hot section, as they may have records from their work order.
Keep in mind that when a CTVR is changed, it must be done in accordance with information in the engine maintenance manual. One must replace the CTVR with a like flow class CTVR to avoid having performance issues upon reassembly.
There is no Alternate Means of Compliance (AMOC). The only “fix” is to remove any CTVRs that were repaired to the process mentioned in the AD note by STI and install a compliant CTVR.
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Pratt & Whitney Canada Corp. PT6A-34, -34B, -34AG, -114 and -114A
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