The responding FAA inspector stated that the accident flight was a test flight of a newly installed GPS system. The pilot told the inspector that the airplane was in a steep bank to the right, maneuvering for another pass, when he encountered a slight buffet. He applied flaps and the buffet went away. As he continued in his steep bank turn to the right, he encountered another buffet that was more pronounced. He added additional flaps and the buffet went away. He encountered a gust of wind that started rolling him further to the right. He applied full left aileron and full left rudder pedal. He knew he was going to crash and was trying to slow the airplane down before the impact. The left wing impacted the ground first followed by the engine, separating. The airplane cart wheeled before coming to a stop upright. The FAA inspector stated that mechanical discrepancies were not reported nor discovered. The airplane owner felt the pilot turned tighter than normal; he observed the maneuver before the accident. The wind at the Golden Triangle Airport (GTR), Columbus, Mississippi, at the time of the accident were from 270 degrees at 4 knots.