The pilot stated that the helicopter had undergone an annual inspection at the helicopter manufacturer and was retuning when he felt a "sudden" yaw to the left during cruise flight about 32 miles from the destination airport. The pilot then performed an "immediate" descent to a clearing and about 60 feet above ground level and 30 miles per hour, the engine quit. The helicopter landed on its skids and spun 180 degrees, impacting a tree with its tail rotor. The tail boom separated from the fuselage and a fire ensued consuming about 10 acres of land. The pilot exited the helicopter through the "partially jammed" passenger door because the pilot door was "jammed." The pilot received minor injuries. Examination of the engine revealed a cylinder head that was separated from its barrel.