Incident Overview
A pilot reported that during a return flight for another load of chemicals, the helicopter's engine misfired several times. The engine then ran smoothly for about one minute before misfiring again and subsequently quitting while the helicopter was approximately 150 feet above ground level (AGL).
Maneuver and Landing
The pilot chose to clear over a cornfield and land in a bean field. During the clearance over the corn, the rotor RPM decayed. The helicopter landed hard, and the main rotor blades struck the tail boom.
Post-Accident Findings
Examination of the helicopter's fuel system revealed about one pint of water in the fuel tank sumps. Additionally, rust was found in the fuel valve.