Following selection of the landing gear in preparation for a landing at Alice Springs the gear lights indicated that the main gear was locked down but the nose gear was unsafe. A visual inspection confirmed that the nose gear was not fully extended. The pilot attempted, without success, to retract the gear using the normal system and to extend it using the emergency extension system. He was provided with assistance from the airport control tower by an experienced pilot during this process. The pilot eventually landed the aircraft on runway 06 with the nose gear still partly retracted. During the post-accident inspection the landing gear worked correctly when the normal and emergency systems were tested. Whilst no specific fault was found, landing gear operating times, when using the normal system, were longer than expected indicating a possible defect in the landing gear motor. The emergency extension system is designed to allow the gear to free-fall into the down position. The nose gear is fitted with springs to help overcome the slipstream effect. The aircraft's manufacturer recommends that the airspeed be reduced to below 92 kts when the emergency extension is to be used to reduce this effect. Information provided by witnesses indicated that the pilot appeared unsure of the landing gear emergency extension procedures and that he attempted to operate it at a speed well in excess of 92 kts. It is possible that the higher airspeed prevented the nose leg from locking into the down position.