The owner of the experimental Quicksilver MXL II purchased the airplane from a previous private owner. The present owner assembled the airplane independently. The pilot agreed to test fly the airplane for the owner, and the accident flight was the first flight since assembly. After a satisfactory preflight inspection, the pilot took off and climbed to about 60 or 70 feet. He then applied left rudder and left “stick” to initiate a left turn. When he attempted to roll out of the turn, the airplane did not respond, and the left bank continued to increase. The pilot applied right spoiler, and shifted his weight by leaning-over into the right seat. The airplane impacted the ground in a nose low, left bank, resulting in substantial damage. Winds were reported light and variable in the area at the time of the accident. Examination of the wreckage was inconclusive.