At about 1930 Pacific time, a passenger was seriously injured by walking into a moving propeller while disembarking from an OMF-100-160 at Van Nuys Airport. The passengers arm was broken in two places and the pilot was not injured. The airplane sustained minor damage. The pilot taxied the airplane to the base of the tower after landing. The passenger got out of the airplane and walked into the propeller. The operator of the aircraft reported that he was not informed of the accident by the pilot, but discovered a nick on the propeller the day following the accident and could not determined its origination. The accident pilot began his training at the flight school, but then changed schools. After he received his private pilot certificate, he returned to the school as a renter pilot and went through an extensive flight check.