As the aircraft approached Jandakot Airport the pilot noticed an un-commanded increase in propeller rpm which he was unable to correct with the propeller control lever. The pilot retarded the throttle and as a result regained some control over the propeller. Shortly after the pilot reduced power the engine began to make unusual noises and the cockpit filled with smoke. The pilot decided to make an emergency landing on the only clear area available, a disused rubbish dump. The engine failed completely during the approach to land. On touch down the aircraft collided with a mound of earth and overturned. The No.6 cylinder and piston exhibited signs of severe detonation probably caused by an unserviceable spark plug. The detonation had burnt a hole through the piston and this allowed all of the engine oil to be either burnt or pumped overboard from the now pressurised crankcase. The loss of engine oil caused the propeller to move to the fine pitch stops (propeller overspeed) and eventually resulted in a complete engine failure. The pilot reported that, up until the time he observed the unexpected increase in propeller rpm, there were no indications that the engine was anything but serviceable.
