On the morning of the accident a periodic inspection had been completed on the aircraft. Following this inspection, the pilot, accompanied by an engineer, carried out a satisfactory test flight in the helicopter. The pilot then lunched with the engineers and after farewelling them at the airport was driven to the helicopter to prepare for the flight back to the mustering camp. The helicopter was later observed by a stockman who was travelling in a vehicle towards the mustering camp. When the helicopter was first seen it was flying at a height of about 200 feet above the tops of the trees in the direction of the camp. It then appeared to stop, turn abruptly through 90 degrees to the left, roll to the left and spin through 360 degrees before impacting the ground inverted. At about the same time as the helicopter turned to the left an object was seen to fly horizontally away from the aircraft to the right. After ground impact a fire broke out and engulfed the wreckage. An extensive search of the area failed to locate the object that had fallen from the helicopter. However it is believed that the object may have been one of several cans of oil or grease the pilot was known to have carried in the aircraft. The examination of wreckage did not reveal any defect in the helicopter which was likely to have contributed to the occurrence. The reason for the loss of control by the pilot could not be determined.