As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RT ENGINE STARTED RUNNING ROUGH, THEN STOPPED AND WENT INTO FEATHER. AC LANDED WITHOUT INCIDENT. UPON INVESTIGATION IT WAS FOUND THAT WHEN THE PROPELLER WAS ROTATED THE AFT CYLINDERS (NR 3, NR 4) PISTONS WOULD NOT MOVE NOR DID ANY ACCESSORIES ON THE BACK OF THE ENGINE MOVE. SUSPECT A CLEAN CRANKSHAFT FAILURE (FRACTURE). NO EXTERNAL CRANKCASE DAMAGE NOTED. (K)