Prior to landing, the pilot confirmed that the landing gear was down (three greens) on the downwind leg and again on final for landing. Approximately 2 to 3 seconds into the landing roll, the right landing gear collapsed allowing the right propeller, landing light and flaps to contact the runway. After the aircraft came to rest on the grass, the pilot and passengers egressed without injury. Maintenance organisation inspection revealed several anomalies, which were not conducive to the continued proper functioning of the landing gear retraction system. The significant factors determined from the inspection were: 1. A lack of lubrication of the landing gear system. 2. A bush missing from the right main gear outboard drive tube. 3. Main landing gear system was out of rigging.