The private pilot reported that during the local pleasure flight the engine started to run rough and he thought that it was as a result of carburetor ice. The pilot applied carburetor heat and after about 3 minutes the engine still did not seem like it was running smoothly. The pilot initiated a climb, however the airplane would not gain altitude so he opted to make a precautionary landing on a sandbar in a river. After touch down on the rough and bumpy surface, the pilot applied braking action. The airplane nosed over and came to rest inverted after the wheels dug into an area of soft sand.

The wings and the left side lift strut were substantially damaged.

The pilot did not report any mechanical failures or malfunctions with the engine or airplane that would have precluded normal operation.

The nearest weather reporting facility was located about 27 nautical miles to the northwest of the accident site. About the time of the accident, the reported temperature of 30oF and dew point of 16oF was at the edge of the range on the carburetor probability chart of icing at glide and cruise power.