What was found
DURING LEVEL FLIGHT THIS AIRCRAFT SUSTAINED LOSS OF PROPELLER. AIRCRAFT LANDED ON A COUNTY HIGHWAY SATISFACTORILY WITH NO DAMAGE OR INJURIES. INVESTIGATION REVEALED THE ENGINE CRANKSHAFT FAILED IMMEDIATELY AFT OF THE PROPELLER ATTACH POINT (THIS CRANKSHAFT HAS A TAPERED SHAFT, NOT A FLANGE). THE PROPELLER WAS LOCATED AT A LATER TIME BY A HIKER IN A STATE PARK. INSPECTION OF THE ENGINE AND PROPELLER INDICATES THE PROBABILITY THAT THE ENGINE HAD SUSTAINED SUDDEN STOPPAGE AT A PRIOR TIME. THIS MAY HAVE RESULTED IN A MINUTE CRACK/FRACTURE THAT EVENTUALLY PROPAGATED INTO THE TOTAL FAILURE OF THIS CRANKSHAFT. SINCE THERE WAS NO DAMAGE TO THE AIRCRAFT OR OCCUPANTS, THIS SITUATION HAD BEEN DETERMINED TO BE AN INC