Following a period a local familiarisation flying, the landing was selected down, pre-landing checks were completed and a green down-and-locked indication obtained. The aircraft subsequently landed on the lower fuselage, main landing gear doors, flaps and propeller tips. During the investigation, a retraction test and partial disassembly of the landing gear mechanism confirmed that the extension cycle had terminated prematurely. This termination was caused by interference with the down limit and indicator microswitches mounting plate by the up limit actuating screw. Movement and activation of these switches, terminated the gear down travel and presented a false gear down-and-locked indication. Only the main landing gear doors extended before the cycle stopped.