N640C

The pilot stated that while landing on runway 28, the airplane "possibly caught a side gust [of wind]." The airplane dropped to the ground and during the landing roll, the airplane started to turn to the left. The pilot and his pilot-rated passenger applied right rudder but were unable to alter the ground track of the airplane. The airplane departed the runway and the nose wheel "dug in" to the ground. The airplane came to rest inverted resulting in substantial damage to the left wing and the vertical stabilizer. The Federal Aviation Administration inspector reported that there were no mechanical anomalies with the airplane that would have precluded normal operations. Wind at the time of the accident was recorded as 240 degrees at 6 knots.