Primary finding
Probable cause
A total loss of engine power due to fatigue failure of the crankshaft. A factor in the accident was the lack of suitable terrain for the forced landing.
Investigator assessment
Analysis narrative
The pilot stated that while conducting an aerial application run, the engine experienced a sudden stoppage. During the forced landing roll, the aircraft collided with a pile of rocks and nosed over. The engine was disassembled, and the the rear throw of the crankshaft was found to have failed due to fatigue.
Source record
Factual narrative
On July 8, 1995, approximately 0830 mountain daylight time (MDT), a Grumman G-164A, N8946H, nosed over during an attempted forced landing in a field about 15 miles north of Burley, Idaho. The commercial pilot was not injured, but the aircraft sustained substantial damage. The aerial application flight, which departed Burley Municipal Airport about 20 minutes earlier, was being operated in visual meteorological conditions. No flight plan had been filed, and there was no report of an ELT transmission. According to the operator, the aircraft experienced a total loss of engine power during an application run, and the pilot attempted a forced landing in the field he was spraying. When the aircraft touched down on the soft dirt of the furrowed field, it encountered a pile of rocks and nosed over. The engine was disassembled by Aero Engines, Inc.. They noted that the rear throw of the crankshaft had failed due to fatigue. -