The pilot had intended to conduct a night freight service to Emerald. There were several thunderstorms in the Emerald area and the pilot elected to divert to Blackwater, 70 kilometres to the east. On arrival in the Blackwater area, the pilot report that he commenced holding at an altitude about 1700 feet above ground level, while he waited for the runway lights to be displayed. The aircraft then entered cloud and severe turbulence was encountered. The pilot stated that his headset was thrown from his head and that he accidently knocked the gear lever into the down position. He said he made no further control inputs. The aircraft struck the ground in a 40 degree turn to the right, at a shallow angle of descent, about 250 metres to the east of the Blackwater runway. The aircraft rotated to the right and slid for about 150 metrtes before coming to rest. The maingear, right engine, aileron and both flaps had been torn from the aircraft during the impact sequence. Reports from ground witnesses indicate that the aircraft was being flown at an altitude of about 400 feet above ground level. It was established that there were thunderstorms in the area at the time but it was not possible to confirm the pilot's report of their severity. The damage to the aircraft suggests that contact with the ground was at a relatively low rate of descent. The investigation did not determine the cause of the accident.