The airplanes rotating propeller struck and injured a deplaning passenger at about 1138 Central time. The airplane received minor damage; the passenger was seriously injured and the pilot, who was the only other person remaining on board, was not injured. Visual conditions prevailed. Witnesses at the scene said the airplane had just returned from a flight where three parachutists had jumped from the airplane. The passenger had been aboard to observe the jump operations. The airplane was stationary on the taxiway with its engine operating when the passenger exited the right door, walked forward and was struck by the propeller.