The airplane was destroyed after collision with terrain and a post-crash fire at 1105 Eastern time; the private pilot was fatally injured. Visual conditions prevailed. The flights purpose was to search for a windsock that detached from its mount due to strong winds earlier in the week. A pilot-rated witness observed the accident flight from start to finish. After some maneuvering, he observed the airplane in “a very low, tight left downwind.” The airplane then entered a tight, steep, low-speed left bank the witness estimated was greater than 45 degrees. After overflying the runway centerline, the pilot pulled the nose over sharply and was in about a 45-degree bank when the left wing dropped and the aircraft dove to the ground.