As the aircraft became airborne the pilot heard a loud bang and upon inspection noticed that the left flap was holed and buckled. The elevator trim had also been damaged and was immovable. This resulted in the aircraft tending to fly in a nose high attitude. The pilot assumed that one of the mainwheels had been dislodged and decided to fly the aircraft to Townsville where emergency services were available. Enroute he was contacted by radio from Scartwater Station and advised that the aircraft was missing a mainwheel. After the pilot received advice from a flying instructor, the aircraft was successfully landed at Townsville. An inspection of the aircraft revealed that the left landing gear torque link bolt had failed as a result of fatigue cracking which had originated from a poorly machined lubrication groove.