On May 13, 2012, about 1454, Pacific daylight time, a Schweizer 269C-1, N61482, sustained substantial damage during an off-airport landing near Hillsboro, Oregon. The helicopter was registered to and operated by Hillsboro Aviation Inc., Hillsboro, Oregon, under the provisions of Title 14 Code of Federal Regulations Part 91 as an instructional flight. The certified flight instructor (CFI) and private pilot receiving instruction were not injured. Visual meteorological conditions prevailed and a company flight plan was filed for the flight. The local flight originated from the Portland-Hillsboro Airport (HIO), Hillsboro, Oregon, about 1415.In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the CFI reported that after departure, he located an off-airport landing area at an elevation of about 1,000 feet mean sea level (msl) to practice off airport landings. After circling the area, the pilot receiving instruction initiated an approach to the landing area from the south. Following an uneventful landing and takeoff, the pilot receiving instruction circled the area and initiated a second approach from the west to a hover over the intended landing area. The CFI observed the engine revolutions per minute (RPM) at the bottom of the green arc, about 2,500, and asked the pilot receiving instruction to bring the RPMs back to the top of the arc. The pilot informed the CFI that they were at full throttle and the CFI took control of the helicopter. About 30 seconds later, the CFI turned the helicopter to the north and initiated takeoff. As the helicopter transitioned through effective translational lift (ETL), the CFI observed the RPMs drop to about 2,300 to 2,400 and the helicopter began to descend. The CFI maneuvered the helicopter towards a level road, however, was unable to make it. Subsequently, the helicopter landed on sloping terrain and the tail rotor struck the ground. In a written statement to the NTSB IIC, the pilot receiving instruction reported that the first off-airport landing was performed to the north and was uneventful. The pilot initiated a second approach to the same landing area to the east and maneuvered the helicopter to an approximate 1 to 3 foot hover, when the CFI told him to roll on throttle as the engine RPM was at the bottom of the green arc. The pilot further reported that the CFI took over the controls, verified the gauges, and initiated a takeoff to the left. The CFI accelerated the helicopter over the ground as it sloped downhill, however, the engine RPMs were "drooping." The pilot stated that he last observed the engine RPM needle indicate between 2,200 and 2,300 RPM and could hear the engine "drooping." He added that as the CFI attempted to land the helicopter on a road, he heard the sound of the engine and rotor RPM dropping as the helicopter landed in a clear area just below the road. Both the CFI and pilot receiving instruction did not recall if they heard a low rotor RPM warning or saw an illuminated warning light during the accident sequence. Review of the Pilot's Operating Handbook for the accident make/model helicopter revealed that the green arc of the engine RPM is from 2,530 to 2,700 RPM. Examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the helicopter sustained structural damage to the tailboom and the vertical stabilizer was separated. The FAA inspector stated that following recovery of the helicopter and a brief inspection of the engine, the engine was started and ran uneventfully with no anomalies noted.