Thank you, TD for your insight. I understand PMA parts don't even require extensive testing if they can show, strictly on paper, that their specs are the same as the OEM. This seems to be, at best, a questionable practice.
I recall a time when one of our engines came off wing for some unscheduled maintenance. The OEM refused to overhaul the engine with the non-OEM parts, despite the parts being fully compliant with the regulators. I believe there were filters and an IDG cooling assembly involved. The filters should have been a non-issue since they were being replaced as part of the maintenance, but it all got some squawks from the folks at the OEM maintenance facility.
This convinced our maintenance chief (exec) to never use non-OEM replacement parts again - at least on the engine cores. ACM bits and hydraulic fittings, two areas where you would think one would want maximum reliability, continue to be allowed to use the non-OEM, PMA approved bits. Go figure.
Back to this event: If a PMA turbine blade is heavier than the OEM, would it not be an issue for not only balance, but stress on the supporting disk?