Accident Details
A pilot reported that while pulling up out of a field and initiating a turn, a loud bang was heard accompanied by an abrupt reduction in power. An emergency landing was performed, during which the airplane nosed over. Upon inspection, the entire propeller assembly was found to be missing, having separated at the crankshaft flange. A propeller blade was recovered over a month later. Examination of the blade revealed it had broken off at the blade root.
Prior to the event, the pilot noted that the propeller had been leaking oil. The propeller was sent to a propeller shop for inspection to identify leaks and cracks. According to the pilot, the shop found no cracks and replaced the seals. The propeller was subsequently returned to service. After seven hours of flight, the propeller failed.
A metallurgical laboratory reported that the propeller failed with a transverse fracture in the threads at the base of the blade. No other details about the aircraft or location were provided in the source.