What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
The pilot was attempting to stop quickly to meet an ATC request. To try and gain maximum effectiveness of the brakes, the pilot attempted to raise the flaps to dump lift. There are apparently several factors which contribute to pilot confusion in this aircraft including changes in BE58 design (where gear flap handle locations were swapped), similarity in handle color and size, and that the two handles are in mirror locations on either side of the throttle engine controls. These issues, primarily the swap of location depending on year - as stated by the pilot, caused his confusion in his hurried attempt to retract the flaps. Instead, the gear was accidentally commanded to be raised apparently just after touchdown, and before there was enough weight on the wheels to deactivate the system.
As the FAA filed it
THE PILOT WAS ATTEMPTING TO STOP QUICKLY TO MEET AN ATC REQUEST. TO TRY AND GAIN MAXIMUM EFFECTIVENESS OF THE BRAKES, THE PILOT ATTEMPTED TO RAISE THE FLAPS TO DUMP LIFT. THERE ARE APPARENTLY SEVERAL FACTORS WHICH CONTRIBUTE TO PILOT CONFUSION IN THIS AIRCRAFT INCLUDING CHANGES IN BE58 DESIGN (WHERE GEAR FLAP HANDLE LOCATIONS WERE SWAPPED), SIMILARITY IN HANDLE COLOR AND SIZE, AND THAT THE TWO HANDLES ARE IN MIRROR LOCATIONS ON EITHER SIDE OF THE THROTTLE ENGINE CONTROLS. THESE ISSUES, PRIMARILY THE SWAP OF LOCATION DEPENDING ON YEAR - AS STATED BY THE PILOT, CAUSED HIS CONFUSION IN HIS HURRIED ATTEMPT TO RETRACT THE FLAPS. INSTEAD, THE GEAR WAS ACCIDENTALLY COMMANDED TO BE RAISED APPARENTLY JUST AFTER TOUCHDOWN, AND BEFORE THERE WAS ENOUGH WEIGHT ON THE WHEELS TO DEACTIVATE THE SYSTEM.