As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT THE TRANSITION FROM DECENT TO LEVEL FLIGHT ON A SEEDING PASS, PROP RPM WAS INCREASED AND A VIBRATION WAS FELT. AS THE THROTTLE WAS ADVANCED THE VIBRATION INCREASED DRAMATICALLY. THE ACFT WAS FORCED TO LAND AND AT LOW SPEED, FLIPPED OVER AS IT BROKE THROUGH A FOOT OF SNOW. ON SCENE INVESTIGATION REVEALED THAT ONE OF THE COUNTERWEIGHT BEARING SHAFTS HAD SHEARED, AND WAS NO LONGER PENETRATING THE PROPELLER BLADE.