Primary finding
Probable cause
The improper decision of the pilot to execute a precautionary landing to an unprepared field due to a supercharger shaft failure.
Investigator assessment
Analysis narrative
The pilot noted a partial power loss and dumped his chemical load. He then attempted a precautionary landing on an unprepared field. During the landing roll the airplane nosed over. Examination of the engine revealed the supercharger shaft had failed resulting in the engine power output being reduced to that of a normally aspirated engine.
Source record
Factual narrative
On September 29, 1994, about 1715 central daylight time, N48572, a Grumman G-164B, registered to Barham Brothers Inc. crashed near Greenwood, Mississippi, while on a 14 CFR Part 137 aerial application flight. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The airplane was substantially damaged and the pilot reported no injuries. The flight had originated from a local dirt road about 15 minutes earlier. The pilot stated that when he added power the rpm increased but the manifold pressure did not. He dumped his chemical load and attempted a forced landing to a plowed field. During landing roll the airplane flipped inverted. Examination of the engine by local FAA personnel revealed that the supercharger shaft and bearing had failed. -