The pilot reported that during cruise at 2,300 ft the engine gradually lost power until he was committed to a forced landing. During the forced landing the aircraft flew through the tops of 40 ft trees and then under a powerline. The aircraft then hit and killed two sheep, ran through a depression, became airborne again and finally hit the ground heavily before coming to a stop. The engine is a sealed rotary liquid cooled unit which can only be dismantled at the manufacturer's facility in England. A post-accident inspection revealed a coolant hose had detached from the water pump but it could not be determined if this initiated the engine failure or was a result of the accident. Traces of internal seal material were found in the exhaust system so it is possible that a seal failure initiated the engine failure. The owner does not intend to return the engine to the manufacturer for dismantling.
