On June 17, 1995, at 2230 hours Pacific daylight time, a Bell 47-G5 helicopter, N7923J, lost power to the main rotor and collided with crops while returning from an aerial application operation near Coalinga, California. The aircraft was operated by Breen Aviation, Inc., of Lemoore, California. Visual meteorological conditions prevailed at the time and no flight plan was filed. The helicopter was destroyed in the collision sequence. The certificated commercial pilot, the sole occupant, was not injured. The flight originated at a private strip near Huron, California, about 2200 hours as a local area agricultural application flight. The pilot reported that he had just lifted off from a refueling truck and was returning to base from applying chemicals to a field when he noted a split in the engine/rotor tachometer. The engine rpm's began to increase while the main rotor speed began to decay. He was attempting to correct the problem with collective and throttle manipulation when the helicopter collided with the ground. The helicopter was examined by a Federal Aviation Administration (FAA) airworthiness inspector from the Fresno, California, Flight Standards District Office. He reported that no abnormalities were noted with either the engine, the transmission, or the freewheeling unit. Heat discoloration and burned oil residue were noted on the clutch.