On June 30, 1999, about 0700 hours Pacific daylight time, a Hiller UH-12ET, N7173F, was substantially damaged during a forced landing in a rice field at Williams, California. The commercial pilot was not injured. The helicopter was being operated by Pacific Valley Aviation of Colusa, California, under the provisions of 14 CFR Part 137. A company visual flight plan was filed. Visual meteorological conditions prevailed for the local area agricultural flight, which originated near the field to be sprayed about 0630. The pilot stated that the engine abruptly quit while spraying the rice field and the forced landing resulted in the severing of the tail boom. He reported the turbine powered helicopter had been fueled the day before the accident, however, he did not visually confirm it. He had only flown 0.5 hours during this flight. Subsequent examination of the fuel system revealed a broken wire at the aft liquidometer. According to the UH-12E maintenance manual, an open circuit between pin A of the fuel gauge and pin C of the aft tank liquidometer would cause the gauge to indicate 34 gallons when the tank is empty. The pilot/operator failed to file a Safety Board Pilot Operator Accident Report, form 6120.1/2.