Incident Overview
A helicopter engaged in controlled burning of timberland experienced a partial loss of engine power while operating at an altitude of approximately 20 feet over wind rows of organic material. The pilot reported that he was unable to maintain a hover and subsequently landed on rough terrain. Following touchdown, the helicopter rolled over, and the main rotor blades contacted the ground.
Engine Examination
During an examination of the engine, all eight spark plugs were found with evidence of lead fouling. In the number four cylinder, the electrodes of the bottom spark plug were completely bridged with lead. The pilot stated that the top spark plug in that cylinder was dirty with carbon.
Aircraft and Operations
The helicopter was being used in controlled burning operations. No other details regarding the aircraft type, registration, or operator were provided in the source material.