While cruising at 3000 feet, the aircraft suddenly encountered strong turbulence. Almost immediately afterwards, the engine commenced to run roughly and the pilot was unable to maintain height. He intended to carry out a precautionary landing on a freeway, but then sighted a strip nearby and positioned the aircraft for a left circuit. He subsequently advised that he elected not to lower the landing gear because he considered that the aircraft would have rolled beyond the end of the 550 metres long sealed strip. The aircraft touched down some 350 metres beyond the threshold and slid for 134 metres before coming to rest. Investigation disclosed that the exhaust valve guide clearances in five cylinders were less than the minimum specified by the engine manufacturer. The engine power loss resulted when an exhaust valve in one cylinder became jammed in the valve guide by a build-up of carbon deposits. The loss of power occurred over unfavourable terrain, and the pilot had been committed to a downwind approach to the strip selected for the forced landing.

The pilot had only recently arrived in the area and had not operated from this strip previously. On his first take-off from the strip he decided to employ a short field technique and lifted the aircraft off the ground at 50 knots. The aircraft became airborne after a ground roll of about 250 metres but after travelling a further 110 metres the wingtip struck the ground, the aircraft landed heavily and ran off the side of the strip. The pilot continued with the attempted take-off and the aircraft travelled a further 325 metres before the take-off was abandoned when the aircraft struck trees. The Pilot's Operating Handbook gives the climb speed after a short field takeoff as 57 knots. The prevailing wind at the time was a crosswind from the right and the pilot believes he may have encountered some tailwind component during the take-off. This combined with a lower than recommended climb speed probably resulted in the aircraft stalling before contacting the ground. After the aircraft had run off the strip it was travelling downwind over soft ground and thus would have required a higher groundspeed than that probably expected by the pilot before it became airborne.

As the helicopter was cruising at 1000 feet agl, the engine suffered a complete loss of power. An autorotation was commenced and the pilot headed the aircraft towards a clear area, to land. At the completion of the landing flare, the heel of the skids dug into the ground and the main rotor blades struck the tail boom. An examination of the engine determined that the fuel regulator diaphram stem had suffered a fatigue failure. This allowed the diaphram to shut off fuel flow to the engine. The pilot elected to carry out a zero speed touch down because he believed that the terrain was unsuitable for a run-on landing, but he misjudged the landing flare.

The aircraft was the only known one of its type in the country, and had been imported by the pilot in 1982. It had not been flown since April 1984. The pilot intended to ferry the aircraft to a neighbouring strip, but about 7 minutes after DEPARTURE the aircraft was seen to turn back. Approaching the DEPARTURE point, the aircraft suddenly pitched up, and shortly afterwards the left wing failed. The pilot attempted to use the recovery parachute, but this became entangled in the rotating propeller and the aircraft fell to the ground. It was likely that the pilot had abandoned his intended flight because of turbulence in the area. The left wing of the aircraft had folded in flight following failure of the lift strut, and the aircraft was in an extreme attitude when the recovery parachute was deployed. The pilot was not a member of the Australian Ultralight Federation, and had not contacted any local members for guidance or assistance prior to the flight.

After takeoff, at about 100 feet above ground level, the engine began to surge. The pilot changed the fuel tank selection and operated the auxiliary fuel boost pump but the engine did not regain power. The pilot then manoeuvred the aircraft in an attempt to find a clear area to land. However, he was unsuccessful and the aircraft collided with trees at a low forward speed. During the impact sequence a fire broke out and almost completely consumed the cabin area and the inboard sections of the wings. Despite the extensive fire damage, small amounts of water and rust were found throughout the fuel system. No other defects were discovered which might have explained the reported engine malfunction, and it was likely that the power loss was caused by water contamination of the fuel. The method by which the water entered the fuel tanks was not established, but may have resulted from condensation and/or the ingress of rain water through the tank caps. The water had not been detected by the pilot during his pre-flight inspection.

Prior to attempting the landing the pilot carried out an aerial inspection of the strip. The aircraft touched down on a gravel road leading to the strip, however, the ground track of the aircraft was effected by a windrow along the side of the road and the pilot was unable to control the aircraft. The pilot applied power to carry out a go-around, but the right main wheel struck a car tyre, which was used to mark the strip threshold, causing the aircraft to veer to the left towards a fence. The pilot managed to manoeuvre the aircraft over the fence but it struck the ground, wingtip first, in an adjacent paddock. The majority of the surface of the strip within the boundry markers consisted of a four metre wide road and the pilot was apprehensive about its use. However, following the conduct of a circuit at the strip by the aircraft's owner, the pilot decided to use the strip as the passengers were waiting to depart for Geraldton. On the return flight the pilot was apprehensive about the landing, but decided not to divert to a nearby airfield because of the likelihood of the passengers experiencing subsequent transportation delays. To increase the landing distance available, the pilot decided to land short of the threshold marked by the tyres at the edge of the road. Once on the ground the pilot's view of the tyres was restricted by long grass.

During the take-off run, when the indicated airspeed was about 40 knots, the pilot saw three wallabies run onto the strip in front of the aircraft. He rotated the aircraft in an attempt to avoid the animals but one of them collided with the tailplane. The pilot closed the throttle and landed the aircraft. The fencing around the aerodrome was inadequate to keep out native fauna and there was high vegetation close to the sides of the strip. The pilot stated that he had not previously seen wallabies within the boundaries of the aerodrome. This accident was not the subject of an on-site investigation.

At the completion of a local pleasure flight the pilot decided to carry out three practice circuits. The first two landings were without incident but on the third landing the aircraft touched down on the right mainwheel and bounced. The pilot applied power in an attempt to stabilise the aircraft but the angle of bank to the right increased and the right wing struck the ground. The aircraft cartwheeled onto the left wing and came to rest inverted, 190 metres to the right of the runway centreline. The landing was attempted in gusty crosswind conditions. The aircraft manufacturer's owners manual recommends that a minimum flap setting be used in these conditions, however, on this occasion the pilot selected full flap. The pilot stated that when the aircraft bounced he attempted to raise the right wing by tha application of left aileron but seeing the skid ball was well out to the right, he then applied right rudder. The aircraft then rolled rapidly to the right and the wing struck the ground.

After joining the circuit, the pilot noticed some cattle standing at the side of the strip. So as to avoid them should they suddenly decide to run onto the strip during the landing, he decided to carry out a short field landing. When the aircraft was about 15 feet above the ground on final approach, the pilot reported that it entered a rapid sink. He flared the aircraft and it landed prior to the threshold. During the landing roll the nosegear was torn off after it struck a drum that was being used as a strip threshold marker. There was a 200 metre high escarpment situated about 1.5 kilometres from the end of the strip. Although the strip could have been used for two way operations, the pilot stated that he did not apply power when the sink rate developed because he believed that he would not be able to carry out a go-around because of the position of the escarpment.

At about 200 feet agl after take-off, the engine began to vibrate and lose power. The pilot turned the aircraft to the right to position over more suitable terrain. The aircraft was stalled into small trees and bushes before touching down heavily on the nosewheel, which broke off. The aircraft then overturned and came to rest inverted. The power loss was caused by two engine exhaust valves sticking open. Although the valves were found to have been set at the minimum recommended clearance, a build up of combustion residue was present which probably restricted valve movement. Operations in high ambient temperatures involving slow flight and reduced engine cooling at rich mixtures can promote a combustion residue build up reducing valve guide clearance and resulting in valve sticking. The aircraft had been operating in the western Queensland summer conducting sheep survey operations.