N63HE

The pilot had flown his airplane for about 1/2 hour when he decided to land on a snow-covered lake that he had previously landed on numerous times during this winter. The pilot said the landing felt normal and he maintained the flare as the airplane skis started to touch down. After touchdown, the airplane continued to ski for 40 feet until it nosed over. He exited the plane, walked the tracks of the skis, and did not find any objects that could have caused the accident. The pilot said that the temperature was about 40 degrees F. He indicated that the snow was sticky and that the skis traveled over a soft spot before the nose over. The pilot reported that there were no mechanical malfunctions with the airplane in reference to the landing.