On August 17, 2007, at 1600 mountain daylight time, a Cessna 140, N89492, piloted by a private pilot, received substantial damage on impact with a ditch during landing when the airplane veered off runway 15 (4,800 feet by 60 feet, concrete) at Grant Municipal Airport (GGF), Grant, Nebraska. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was not operating on a flight plan. The pilot and passenger were uninjured. The local flight originated from GGF at 1550 mountain daylight time. The pilot stated about 50 feet above the runway, the controls would repeatedly go from firm to mushy. At touchdown, the controls went mushy and a gust of wind hit the side of the airplane which then windmilled the airplane into the wind. The pilot reportedly was able to straighten the airplane but the rear of the airplane fishtailed 2 or 3 time before departing off the east side of the runway. The airplane then traveled about 30 feet and impacted a ditch.