The flight was at 13,500 feet overhead the airport, preparing for the skydivers to jump. The pilot turned on the green light to initiate the jump. He then felt the aircraft shudder, but did not lose control of the airplane. After most of the jumpers had left the airplane, one of the skydivers came forward and notified the pilot of damage to the tail. After a controllability check, the pilot landed the airplane without further incident. Structural damage to the left horizontal stabilizer was found after the flight. The Federal Aviation Administration (FAA) inspector reported that a skydiver was standing at the door of the airplane when his reserve chute inadvertently deployed, pulling the skydiver out of the airplane. The skydiver then struck the horizontal stabilizer after being pulled from the airplane. The FAA inspector found the parachute to have a current inspection; no anomalies were found.