As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE INSPECTION, CRACKS WERE DISCOVERED IN THE HUB AT AFT EDGE, MATING SURFACE TO ENGINE CRANK FLANGE. THE MOST PROMINENT CRACK IS ABOUT .5" LONG. THERE IS NO DAMAGE HISTORY FOR THIS PROP. THE PROP IS INSTALLED UNDER STC SA3104SO TO AN ENGINE INSTALLED ON THE ACFT UNDER THE SAME STC. NO ISSUES HAD BEEN REPORTED BY THE FLIGHT CREWS PRIOR TO THIS FINDING.