Incident Narrative
The pilot reported that after spraying an onion field, he was departing for the next job. During the departure, he observed an increase in engine RPM and a decrease in rotor RPM. As a result, he was unable to maintain altitude and initiated an emergency landing from approximately 200 feet above ground level.
Emergency Landing
Prior to the landing, the pilot noticed smoke and flame coming from behind the cockpit area. The source of the smoke and flame was apparently the engine transmission area.
Post-Accident Examination
A teardown inspection of the transmission and clutch assembly was conducted. The inspection revealed discoloration of the clutch assembly. This discoloration was evidence that the clutch had been overheated from friction.
Findings
The investigation identified discoloration of the clutch assembly due to friction-induced overheating. No other causal factors were mentioned in the source.