The aircraft was engaged on a bank-run flight. On arrival in the circuit area at Maitland the pilot observed that the aerodrome was fogbound, and so elected to divert to Warkworth. The pilot reported that when on downwind in the circuit area at Warkworth, the landing gear extended normally and a safe gear indication was observed. Ground witnesses reported that the touchdown of the aircraft on the gravel strip appeared to be normal. At approximately one third of the ground roll distance, the left maingear retracted. The aircraft veered off the strip and slid sideways on wet grass. No fault was found with the landing gear system. The sequence of retraction suggested that the pilot had inadvertently retracted the gear instead of the flaps.
