The pilot reported that he had moved the landing gear to the down position and obtained the green light indicating that the gear was down and locked. During the landing roll, with a crosswind from the left, the right main gear leg collapsed. The landing gear operating system had been stiff during circuits in the previous week. Maintenance inspection determined that the overcentre link on the right gear mechanism was binding. During extension of the gear the push rod apparently bent and the gear struts did not go over centre. The pilot was not aware of this as there is only one light to indicate gear down and this did not indicate the exact position of the gear legs. This accident was not the subject of an on-site investigation.

The aircraft was engaged in a passenger charter operation from Moree to Tenterfield. After landing at Tenterfield, when the aircraft turned off the strip, the left main landing gear broke away and the aircraft settled on the left wing. Prior to the previous takeoff, whilst the aircraft was taxiing at Moree, the landing gear aural warning had sounded momentarily. The pilot and an engineer inspected the landing gear down lock system but no fault was found. The aircraft then operated normally to Tenterfield until the aircraft turned off the strip. Subsequent investigation of the landing gear showed that the forward trunnion pin had became disengaged from the trunnion and the rear pin had migrated some distance aft and finally failed in overload. Movement of the trunnion pins was the direct result of incorrect assembly procedure.

At the start of the take-off run, one propeller blade separated from the hub. The resulting propeller imbalance caused damage to the engine and airframe. The fracture was caused by the growth of a fatigue crack from the second blade retention thread. No material abnormalities or stress concentrators contributed to fatigue initiation. It was estimated that fatigue growth had occurred over a period of approximately 2100 take-off/landing cycles. The Civil Aviation Authority subsequently amended the Airworthiness Directives relating to this type of McCauley propeller, when fitted to agricultural aircraft. These amendments include a reduction in hours between overhauls, and more detailed inspections of the threaded section of the blades.

Circumstances:

The aircraft had been delayed in servicing and repair and had only been released six weeks prior to the accident. This delay had caused the operator/pilot to fall behind in his commitments and, according to some witnesses, caused him to worry about the situation. On the day of the accident, the pilot had just completed spraying a 243 hectare paddock and had landed to reload. After take-off for the new task, the pilot was seen to make an aerial inspection of the paddock before entering the first swath run. At the end of this run, the aircraft collided with a Single Wire Earth Return (SWER) powerline and crashed. It was later shown that the aircraft was in a bank to the right of about 18 degrees. The SWER line ran across one end of the paddock at an angle and on the crop side of a windmill just inside the fence which bordered the road. The line contacted the right main gear and outboard spray boom attachment struts on the right wing. The wire broke after impact, but the aircraft hit the ground heavily on the right main gear. The gear detached from the aircraft, the propeller struck the ground and the aircraft slewed around as it came to rest after some 27 metres of ground travel. The front half of the aircraft was destroyed by fire which broke out almost immediately the aircraft stopped. Two main hypothesis were proposed. One was that the pilot was distracted from a less than demanding task by business worries. The other was that the pilot had perceived that the SWER line was on the right of the windmill and outside the fence and therefore did not present an obstacle to his procedure turn. Neither hypothesis could be substantiated. An additional concern was the fact that the pilot had died from impact injuries in an accident that, prima facie, was survivable. Concern focused on whether the pilot had secured his harness properly and/or whether the inertia reel had failed. Detailed engineering inspection of the inertia reel by the Bureau and the manufacturer could not positively determine the mode of operation of the inertia reel. However, the postmortem report showed that the nature of injuries to the pilot, while sufficient to cause death prior to the fire, were such as to indicate that the inertia reel had probably not failed.

Significant Factors:

The following factor was considered relevant to the development of the accident:

The pilot did not see the powerline in time to avoid a collision.

Circumstances:

The pilot was spotting for sheep in advance of rising flood waters. He landed the aircraft in a paddock to assist a truck driver to unload sheep from the truck. He used the driest part of the paddock, near the tree line, where vehicles and motor bikes had been operating. Before departing, the pilot taxied to the touch-down point and commenced the take-off over the same area used for landing. Once the aircraft passed the end of the landing roll section, the ground became softer, the nosewheel dug in and the aircraft veered to the right. The nose gear broke off and both propeller blade tips hit the ground. The right wing tip struck a one metre high acacia tree while the aircraft continued to slide for about a further 50 metres.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The soft surface was not detected in the pilot's survey of the area selected for landing.

Circumstances:

After one circuit and full stop landing, the pilot taxied again for runway 17 with the intention of a local flight. On the taxiway, near the aircraft parking area, a grader and a road roller were working. The pilot was fully aware of the works in progress. Nearing the grader, the pilot veered the aircraft to the left on to the grass between the taxiway and the runway. There was plenty of room. The aircraft passed the grader and continued north on the grass beside the taxiway. While taxiing at about five knots, the outboard section of the leading edge of the right wing contacted the roller's air filter. The roller was moving slowly south at the time. There were no obstructions to visibility. The pilot had misjudged the clearance between the wing and the roller.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. The pilot misjudged the horizontal distance between the right wing and the roller.

Circumstances:

The pilot reported that on arrival at Lake Julius, a practice forced landing was being conducted with power reduced to idle. The landing gear warning horn sounded but it was decided to leave the wheels up to improve gliding performance. During the pattern, the power was increased to silence the horn and warm the engine while a radio transmission was made, and the power was again reduced to idle. The pilot stated that he was high on final and extended full flap and sideslipped to lose height. The landing gear horn was still sounding but he omitted to lower the landing gear before the aircraft touched down. The instructor stated that the approach was high throughout, and that he was contemplating a go around. When it became apparent that a full stop landing could be accomplished with adequate runway available, he had failed to realise that the landing gear had not been extended. The aircraft came to rest halfway along the 900-metre gravel strip with the landing gear in the retracted position. This accident was not the subject of an on-scene investigation.

Significant Factors:

The following factor was considered relevant to the development of the accident:

1. Pilot forgot to lower the landing gear.

The pilot reported that during the latter part of the landing roll the aircraft ground looped to the left. The right mainplane and right tailplane were bent upward. Inspection of the aircraft revealed that the right maingear had become detached due to the partial shear of the leg attach bolt and nut threads. This was probably due to the abnormally high loads experienced by the bolt when the pre-load ceased to exist.

The pilot reported that he made a normal circuit and approach to land with a touchdown speed of about 60 kts. However, the aircraft bounced and he pushed forward on the control column to recover. The aircraft then touched down first on the nosewheel which immediately collapsed. The aircraft slid to a stop on the nosegear and propeller while remaining on the strip.

During circuit training, the aircraft suffered a complete engine failure. The pilot was unable to reach the flight strip and landed the aircraft amongst trees. One of the two pistons of the two stroke engine had seized in the cylinder, probably due to lack of lubrication.