What happened
While flying at 2,500 feet mean sea level, the pilot experienced sudden and extremely violent vibrations. The vibration was so severe that the pilot feared the engine might detach from the aircraft. In response to the instability, the pilot shut off the engine and performed a forced landing in a field characterized by high vegetation. The pilot was not injured.
The investigation
An FAA report determined that the intense engine vibration was caused by the delamination of a wood propeller across the leading edge and tip of one blade. During the examination, traces of rust were discovered on the wood at the locations where the metal inlay was secured to the wooden blade using steel screws. The propeller manufacturer confirmed that steel screws are the standard component used to attach the leading edge to the wood blade.