On December 27, 1994, approximately 1400 mountain standard time (MST), an Aviat Pitts S-2B, N60823, experienced a nose-over during the landing roll at Afton Municipal Airport, Afton, Wyoming. The private pilot and his passenger received minor injuries, and the aircraft sustained substantial damage. The personal pleasure flight, which departed Casper, Wyoming about 1230 MST, was being operated in visual meteorological conditions at the time of the accident. The flight had originally been on a VFR flight plan, but it had been closed prior to this leg of the trip. There was no report of an ELT activation. According to the pilot, he lost directional control during the landing roll, and the application of power to initiate a go- around only aggravated the directional control problem. The aircraft flipped over after coming in contact with snow covered terrain near the edge of the runway. The pilot said that there were no problems with the aircraft's flight controls or braking system.