The aircraft was cruising at flight level 170 in clear conditions at night. Although no thunderstorms had been forecast, the crew observed some electrical activity on the intended track. The weather radar was reported to have been functioning normally and detected scattered cells. The pilot under check elected to divert to the right of the track to remain clear of those cells and also activated the seatbelt warning chimes twice to alert the nursing sister seated in the cabin. The Captain reported that, although it was dark, ground lights and the weather radar indicated that there were no cloud build-ups ahead of the aircraft after the diversion. Shortly after, the aircraft encountered an area of severe turbulence associated with wispy cloud. During that encounter, one of two stretcher patients sustained minor facial injuries after striking nearby equipment. Both stretcher patients had been restrained at the time of the occurrence.

The pilot was making night spraying runs over a cotton crop. During the third run at about 50 feet above ground level, the engine suddenly lost all power. The pilot attempted a landing at slow speed in a flooded cotton field. Almost immediately after touchdown, the aircraft nosed over and sank into the soft muddy surface. The pilot was able to extricate himself from the partly water-filled cockpit. The subsequent examination of the engine revealed massive internal damage. It was likely that one connecting rod had failed, and this led to similar failures in three other cylinders. The reason for the initial failure was not determined. The pilot had selected the most suitable area available for the forced landing. When the aircraft overturned, the fibreglass roof of the cockpit failed, and cut into the top of the pilot's helmet. Had the pilot not been wearing this protection, it was likely he would have suffered head injuries and probably drowned.

The pilot had booked the aircraft for an endorsement two days prior to the proposed flight. However, due to other commitments the aircraft did not become available until 1900 hours. This was unacceptable to the pilot and he was forced to arrange an endorsement with another training organisation on the following day. This arrangement meant that the pilot's preparation for the proposed flight became somewhat rushed. Additionally, the pilot had studied the pilot's notes for the Partenavia, but it was a different model which had a different fuel system to the aircraft which he subsequently flew. The flight proceeded in instrument meteorological conditions for most of the time. The pilot reported that the fuel gauges indicated just over half full as he passed Oodnadatta. However, from that position on, the fuel gauge indications started to decrease fairly rapidly and because of the worsening fuel situation, the pilot decided to inform Alice Springs Flight Service in order to expedite his arrival. The fuel quantity indications then began to drop at an alarming rate and the pilot decided to make a precautionary landing before the fuel supply was exhausted. After descending to lowest safe altitude, the pilot was able to see the ground through a hole in the cloud cover. He descended through the hole and landed on a flat piece of ground. During the landing run the nose gear collapsed just before the aircraft came to a stop. Due to weight consideration the pilot departed with full main fuel tanks only. He was under the mistaken belief that the total endurance with full main fuel tanks was 470 minutes and had this been so there would have been sufficient fuel to meet all requirements for the flight. However, total endurance with full mains (392 litres) is 314 minutes. Some fuel remained in the outboard fuel tanks but the pilot was probably not aware of this. The pilot calculated that a total endurance of 433 minutes was required for the planned flight. This figure is well in excess of the fuel carried on the flight. As the flight progressed strong headwinds were encountered and the pilot had been airborne for approximately 303 minutes when he made the precautionary landing 94 Km south-south-east of his destination. It was calculated that between 12 to 29 litres of usable fuel remained in the aircraft's tanks on landing. The pilot reported that fuel was being consumed at a faster rate from one fuel tank than the other and that he cross fed to balance the fuel in each main tank. When the aircraft's tanks were dipped after the accident they were found to contain approximately 80 litres of usable fuel, 70 litres in the right main and 11 litres in the right outboard fuel tank. It was later ascertained that the right fuel quantity indicator under read at lower readings and this misled the pilot into thinking that fuel was being used at a faster rate from the right hand fuel tank. It also misled the pilot into thinking that he was almost out of fuel where in fact he had sufficient fuel to fly to his destination, although not with the required fuel reserves. This accident was not the subject of an on-scene investigation.

While the aircraft was on base leg the pilot saw a powered aircraft which had been conducting circuits throughout the day on final approach. He considered that he would land too close behind the other aircraft so elected to land on the grass strip beside the runway. During the landing the long grass impeded the left wing slightly. The pilot corrected but the right wing struck the ground and a ground loop ensued. Examination of the tyre marks indicated that the pilot had actually landed outside the strip markers in an area of long grass and rough ground. Witnesses observed that the powered aircraft had conducted a touch and go landing and was airborne again before the glider crossed the threshold boundary fence.

Circumstances:

The pilot took off with the intention of doing a local flight. However, he could not locate any lift, so he returned for a circuit. While on very short finals the aircraft encountered undershoot windshear. The right wing struck a small bush some 5 to 10 metres short of the threshold. The wing was further damaged in the subsequent contact with the ground. The particular bush has since been removed.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. The aircraft encountered undershoot windshear on very short final approach. This caused the aircraft to undershoot the landing strip.
2. The aircraft collided with an obstruction close to the strip threshold.

Circumstances:

The aircraft was cruising at about 150 - 200 feet above the trees over heavy scrub country when the engine coughed. The pilot started a descent and the engine regained power briefly before stopping completely. Unable to reach a suitable area for an autorotational landing, the pilot avoided two large trees before the aircraft crashed through smaller trees and struck the ground. The aircraft had been operating for some two and one half hours since refuelling to full tanks, which usually provided an endurance of at least three hours. The pilot was in the habit of managing his fuel by reference only to the operating times and by landing to conduct a sight check of the fuel tank contents after about two and one half hours of operations. No reliance was apparently placed on the fuel contents gauge in the aircraft. An inspection of the aircraft after the accident revealed fuel stains over the oil tank, induction plate and main frame. The inspection also revealed that two screws were missing from the carburettor drain tap plate. No signs of the fuel leak were reportedly evident at the previous pre-flight inspection.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. Pilot relied on the times of operation for fuel management in flight and did not refer to the fuel contents gauge in the aircraft.
2. Leaking carburettor fuel drain tap.
3. Engine failure through fuel exhaustion.
4. Engine failure over terrain unsuitable for an autorotational landing.

Circumstances:

The pilot under training was practising circuits and landings in preparation for a Commercial Licence test. When the landing gear was extended on the downwind leg, the nose gear light did not illuminate. The instructor changed light bulbs and the light illuminated so the circuit was continued. The landing was normal until the nose gear collapsed during the ground roll. The aircraft was involved in a similar accident in South Australia on 25 May 1989 and had flown approximately 25 hours since being repaired. A technical investigation revealed the down lock hook had fractured across the "U" section and there was excessive wear in all attachment holes and bushes. The down lock hook failed in overload probably as a result of higher-than-normal loads caused by the excessive wear in the drag link/over centre lock system.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. Inadequate maintenance and repair following a previous accident.

2. Overload failure of the down lock hook in the nose gear mechanism.

Circumstances:

The pilot had been airborne for approximately 15 minutes, carrying out aerial spraying of a newly planted crop. The paddock being sprayed was bounded on its northern and western boundaries by a fence approximately 1.2 metres high. Directly above, and running parallel with the western fence, was a three strand power line, the lower cables of which were approximately five metres above ground level. The pilot had flown above the power lines on each previous spray run, crossing the paddock from east to west. After completing a procedure turn the aircraft was lined up for the clean-up run from west to east. The pilot stated that he forgot about the power lines until they became visual again at close range. Knowing he would not be able to climb the aircraft above the cables in the distance remaining, the pilot elected to fly between the lines and the fence. The aircraft struck the two lower cables of the power lines, tearing the fin and rudder from the airframe. The aircraft continued airborne for approximately one kilometre before rolling to the right and striking the ground. It then began to break up as it cartwheeled across the paddock, finally coming to rest inverted. An inspection of the area revealed that the poles that supported the power lines would have been difficult to see, when approaching from the west, as their outline merged with trees in the paddock.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. The pilot forgot about the presence of the power lines.

2. The pilot did not see the power lines in time to avoid them.

3. The aircraft wire deflector failed on contact with the power lines.

Circumstances:

The pilot reported that the aircraft was part way along a spray run when he heard a change in the engine noise which he described as a hissing/tapping sound. He completed the run but, when the noise increased during the procedure turn, he elected to land the aircraft on a dirt access road between two crops. The aircraft landed with a wind of about 10 knots from the right rear quarter. Shortly after touchdown, the pilot swerved the aircraft to avoid a post. The pilot then experienced directional control difficulties, and the right main wheel entered soft ground at the edge of the central road surface. This caused the aircraft to swing right and enter the crop. As both main wheels encountered the cultivation, the aircraft nosed over, and a fire began in the engine compartment. The cockpit roof was embedded in soft soil. This prevented the pilot opening either door. However, he was able to egress from the cockpit by kicking out the Perspex panel in the left side door. An inspection of the engine revealed that the exhaust pipe from Numbers 1 and 9 cylinders had come loose and was free to rattle and allow exhaust gases to escape past the respective cylinder flanges. This would have caused the noise as described by the pilot. The brass nuts which secure the exhaust to the cylinder head were not found. However, the cylinder head exhaust studs showed witness marks which indicated that neither nut had been in place at impact.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. For reasons which were not established, the numbers 1 and 9 cylinder exhaust pipes were not secured to their respective cylinder flanges.

2. Noise from the loose exhaust pipes and escaping exhaust gases attracted the pilot's attention.

3. The pilot elected to land as soon as possible.

4. The pilot lost directional control of the aircraft during the landing roll. Bureau of Air Safety Investigation

Circumstances:

The flight consisted of one aircraft in a group of three positioning a mobile polling booth. After the passengers were unloaded at Oenpelli, the aircraft flew to Jabiru to refuel, and the pilot rested in the air-conditioned snack bar for about five hours. The aircraft was then re-positioned at Oenpelli and the passengers boarded. The aircraft departed from runway 12 as the wind was 120 degrees at 20 knots, gusting to 25 knots. The temperature was about 40 degrees Celsius. This was not the pilot's preferred runway as the Spencer Range escarpment commences within five miles of the DEPARTURE end of this runway, rising rapidly from sea level, through 500 feet to over 1,000 feet. At some point after take-off, the pilot realised the left engine manifold pressure was steadily decreasing. After completing trouble checks, he feathered the left propeller and turned back towards the aerodrome. When turning onto the base leg, the pilot realised the aircraft would not maintain altitude and could not reach the runway. He then elected to land straight ahead on a dry clay pan. The landing gear could not be extended as the left engine drives the hydraulic pump and insufficient time remained for the pilot to manually extend the gear. The aircraft touched down wings level and skidded for about 135 metres. All four occupants evacuated safely once the aircraft stopped. The investigation failed to determine any pre-existing defect in the left engine. However, impact damage to the undersurface of the engine, may have destroyed any evidence of a pre-existing defect.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. For undetermined reasons, the left engine suffered a partial or total power failure.

2. The aircraft was unable to maintain height on one engine in the high-density altitude conditions.