Incident Overview
While dispensing herbicide, a helicopter experienced an engine power loss, a drop in RPM, and a noticeable vibration. The engine subsequently recovered to full power, causing the helicopter to yaw. This sequence of events occurred three additional times for reasons that were not determined during the flight.
Landing Attempt
During an attempted run-on landing to a field, the helicopter continued to exhibit the same power fluctuations. As the skids made contact with the ground, the pilot heard a loud 'boom'. The helicopter then yawed, the skids separated from the fuselage, and the aircraft came to rest on its side.
Investigation Findings
The investigation was unable to determine the cause of the repeated power losses, recoveries, and associated yawing. No further information regarding the aircraft type, registration, or operator was provided in the available source material.