The pilot was landing the Beech 65-A90, on a 3,000-foot-long, 70-foot-wide, asphalt runway, when the airplane encountered a high sink rate. The pilot applied engine power; however, the engines did not respond quickly enough to prevent a hard landing. During the hard landing, the main landing gear separated and the left landing gear struck the vertical stabilizer. The pilot subsequently performed a go-around and landed on a grass runway, without further incident. The pilot stated he did not experience any mechanical malfunctions. He reported 5000 hours of total flight experience, which included 500 hours in the same make and model as the accident airplane.