The pilot intended to carry out a touch and go landing at the strip, from which he had operated on numerous occasions. He reported that the aircraft floated for some distance before touchdown, whereupon he immediately selected flaps up and applied full power. The aircraft started to swing towards the left, and suspecting an engine failure, the pilot shut down both engines and applied maximum braking. He slewed the aircraft to the right to avoid a dam at the end of the strip. The aircraft was arrested by a wire fence beyond the end of the strip, with the left maingear leg torn off. It was found that the left flap had not retracted, although the right flap had retracted normally and the cockpit indication was that the flaps were up. The strip was narrower than required for an ALA, and was bordered on each side by a one metre high oat crop. As the aircraft swung to the left, it is likely that retardation of the crop on the left wing added to the drag on that side. The aircraft had landed with a tailwind component. During the investigation, it was reported by several persons that asymmetric flap retraction was a known problem on this aircraft type, and was caused by dirt or other contamination of the flap tracks. The symptoms of the malfunction are similar to those associated with a loss of engine power on the particular side. The pilot had not been aware of the problem.
