The pilot of a tailwheel equipped biplane reported that during takeoff he encountered an "unexpected wind gust." Subsequently, the airplane departed the grass runway to the left into "muddy" terrain. The pilot reported that he reduced the power to idle during the runway excursion, but the airplane sunk into the mud and nosed over. A postaccident examination revealed substantial damage to the top left wing.

About the time of the accident 8 nautical miles northwest of the destination airport, an automated weather observing system reported wind conditions of 170 degrees true at 15 knots, gusting to 25 knots.

The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.