19971108032649A

Sightseeing flight. Prop assembly seperated. Crash landed. (From .4) the pilot reported that during the preflight inspection, he examined the propeller while pulling the engine through each cyclinder and found no discrepancies. The aircraft was about 7 minutes into a 15-minute flight when he saw a 'spark or flash' at the 11 o'clock position on the nose, followed quickly by the complete separation of the propeller. He turned the aircraft back toward the airport but had insufficient altitude and landed in a hilly area of a canyon. A postcrash fire began and consumed the aircraft aft of the firewall. The aircraft was examined on site and following recovery of the wreckage. An unsuccessful search was made for the wooden propeller. The metal propeller hub remained attached to the engine crankshaft with fragments of the wood center section intertwined in the bolts. The wood remains were insufficient to determine either the model or serial number of the propeller, or the condition of the boltholes. Both the engine crankshaft splines and propeller hub splines were unremarkable. The remaining pieces of wood from the hub were submitted for laboratory evaluation. The examining labo ratories reported that there was insufficient evidence available from the small fragments submitted to identify an initiating event in the propeller or the failure cause of the wood hub.