The certificated private pilot was making a low pass over a snow-covered airstrip, when he inadvertently allowed the main wheels to touch down. As the airplane touched down, the main wheels contacted deep snow on the runway, and the airplane nosed over. The airplane sustained substantial damage to both wing lift struts, and the rudder. The pilot noted that there were no preaccident mechanical anomalies with the airplane. The pilot did not submit a Pilot/Operator report (NTSB form 6120.1/2).