On April 8, 2007, about 1400 Pacific daylight time, an amateur-built experimental-category Diemert/Rotorway International Exec 162 F helicopter, N173ST, sustained substantial damage during a forced landing subsequent to an in-flight loss of engine power approximately 5 miles south of the Roseburg Regional Airport, Roseburg, Oregon. The pilot/owner of the helicopter was not injured. The helicopter was operated under the provisions of Title 14 CFR Part 91, when the accident occurred. The pilot's planned destination was the Roseburg Airport. No flight plan was filed for the local flight. In a written statement, the pilot reported that after takeoff, he climbed to an altitude of 30 - 40 feet above ground level (agl). As he advanced the cyclic forward to gain airspeed, the engine lost power and he immediately initiated an autorotation. Subsequently, the helicopter impacted the ground and slid into a fence resulting in substantial damage. The pilot stated that as the engine lost power, he noticed the number one Fully Automated Digital Electronic Control (FADEC) light went off and that the secondary FADEC did not function. The pilot added that the loss of engine power was the fifth occurrence of the same nature. Examination of the FADEC Engine Control Units (ECU) at the facilities of Electro-Sim of Tempe, Arizona under supervision of a Federal Aviation Administration inspector revealed that there was a discontinuity of the "L3" ferrite inductor on both the number one and two ECU circuit boards. The Electro-Sim representative stated that both ferrite inductors are digital grounds and a simultaneous failure of the inductors would cause the engine to shut down immediately; and should only one of the "L3" ferrite inductors fail, "the engine would continue to operate, but the sensor/annunciator panel would become inoperative." The reason for the failure was undetermined.