On entering the circuit at Moruya the pilot obtained an unsafe indication of the nose landing gear, after selecting the landing gear down. Ground observers reported that the nose landing gear was not in the full down position, however both main landing gears appeared to be down. The pilot recycled the landing gear but this was unsucessful and resulted in an unsafe indication for both the nose and right main landing gears. Ground observers reported the nose landing gear was still not fully extended. The pilot requested emergency services to standby and tried the emergency extension system, but this was also unsuccessful. When the emergency services were in position the pilot carried out a landing, but the nose and right main landing gears collapsed during the landing roll. Ground inspection revealed a failed hydraulic line in the landing gear extend system. This resulted in the loss of most of the hydraulic fluid, rendering the landing gear system inoperative. The right main landing gear unlocked when the pilot cycled the system, but there was insufficient fluid remaining to retract the landing gear. The emergency system is only effective if used when the landing gear is in the fully retracted position.