On June 19, 2002, about 0900 eastern daylight time, a Cessna 180, N9150C, registered to a private owner operating as a 14 CFR Part 91 instructional flight, experienced a loss of directional control on landing roll out at Harlong Airport in Jacksonville, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The airplane sustained substantial damage. The private pilot receiving instruction and the commercial pilot certified flight instructor (CFI) reported no injuries. The flight originated from Herlong Airport, Jacksonville, Florida, at 0800. The CFI and pilot stated he had made two full stop landings, and one touch and go landing before the accident. He completed his before landing check on downwind and listened to the AWOS weather information. The winds were reported as calm. The pilot made a wheel landing and as the tail wheel began to lower, the airplane started to veer to the left. The CFI got on the flight controls with the pilot and they both applied right rudder. The airplane continued to veer to the left, and the left main landing gear went off the side of the runway and the airplane nosed over. The CFI stated the pilot encountered a gust of wind and lost directional control of the airplane. The 0915 AWOS surface weather observation at the time of the accident at Herlong Airport was: wind calm, visibility 10 miles, ceiling 1,400 overcast, temperature 75-degrees Fahrenheit, dew point temperature 75-degrees Fahrenheit, and altimeter 30.17. Examination of the airplane by an airframe and power plant mechanic for De Bar Aviation located at Herlong Airport revealed sudden stoppage damage to the engine assembly and accessories. The right main landing gear box structure and cabin floor was buckled. A functional check of the left and right brake assembly revealed no anomalies.