Circumstances:

The student was doing the take-off with the instructor talking him through the sequence. As the aircraft became airborne a "thump" was felt. The right main wheel and inner strut assembly had become separated from the outer strut assembly and was hanging below the aircraft attached only by the brake hose. After emergency services were alerted and in position, the aircraft was landed by the instructor on the grass area beside the runway. Inspection of the aircraft showed that the upper torque link lugs, where the link attaches to the outer strut assembly, had fractured. The reason the lugs fractured was not determined.

Significant Factors:

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

1. Fracture of the right main gear leg upper torque link attachment lugs, reason not determined. This accident was not the subject of an on-scene investigation.

The pilot reported that he was to spray a 17 acre crop of cucumbers. He had flown the area twice previously, and knew the hazards to be powerlines and stay wires from the power poles. The stay wires were the more difficult to see so he concentrated on locating these during his aerial inspection of the paddock. At the completion of his first run, which was along the western edge of the area, there were two sets of powerlines. The pilot had planned to fly under both sets but hit the second set as he pulled up from the run. He stated that he had forgotten about the second set of wires. Although the aircraft sustained left wing and aileron damage, the pilot was able to land safely at the operating landing area.

The aircraft was being flown by the owner who had obtained a restricted private pilot licence several hours prior to the accident, and had just completed an endorsement on the type. The front seat passenger was a licenced pilot with slightly more flying experience than the owner. During the landing, the aircraft touched down on one wheel, bounced and yawed to the left. The pilot commenced a go-around but the passenger took control of the aircraft from him. During the attempted go-around, the aircraft was observed to touch the ground again, before flying in a steeply nose high attitude over a parked aircraft and a building. As the aircraft passed over the building a wing dropped and the aircraft subsequently struck a fence post damaging the right stabilator. It became airborne again in a steeply nose high attitude before stall- mushing into the ground, impacting heavily approximately 600 metres from the initial point of touchdown.

The pilot had flown the aircraft to Cockburn Sound to practice circuits. However, after the first landing he found the water conditions too rough to complete a takeoff. The pilot waited for a period in the hope that conditions would improve. Three quarters of an hour later he taxied along Cockburn Sound looking for an area that was suitable for takeoff, but this search was unsuccessful. After beaching the aircraft a second time the pilot observed that the aircraft was taking water. When the pilot attempted to drain the excess water from the bilges he found that the rear bilge pump was unserviceable, and the water had to be drained manually by removing two bungs. The bungs were replaced when the water flow reduced to a trickle after five to ten minutes. The sea state abated after four hours and the pilot decided to carry out a high-speed taxy run during which, if he assessed the conditions were suitable, he could convert the run to a takeoff. The pilot was able to get the aircraft up on to the hull step, however, before he could continue with the takeoff the aircraft suddenly pitched nose-up and then down before nosing over inverted approximately 50 metres from the shore line. Neither occupant was wearing a life jacket although they were carried in the aircraft. Both occupants received injuries which may have required the jackets for survival had assistance not been given from the shore. A screw was found to be missing from a normally watertight panel on the rear fuselage. The screw had been missing since the aircraft was last painted. Tests indicated that water was able to leak into the aircraft via the missing screw hole. Water in the rear fuselage would normally be pumped out by the rear bilge pump, however, it was unserviceable. The pump's impeller had become detached from the drive shaft sometime prior to the accident flight. Tests on the manual draining system used by the pilot indicated that a minimum of 31 litres of water remained in the aft fuselage after draining was apparently complete, when the flow of water had slowed to a trickle. Although the sea state appeared to improve there was still a significant swell running at the time of the accident. The pilot attempted his high- speed run in the direction of the swell instead of parallel to it. It is probable that the combination of an aft centre of gravity, movement of weight associated with the water in the fuselage and the uplift provided by the swell caused the loss of control.

The pilot was conducting a freight charter flight, and witness evidence confirmed that on DEPARTURE he was occupying the left-hand seat. The pilot was accompanied by a friend who was also a commercial pilot, but not endorsed on this type of aircraft. Approximately 18 minutes prior to the estimated time of arrival at the destination, the pilot reported leaving the cruising altitude of 6500 feet on descent. Several minutes after the descent report had been made, a witness about 50 kilometres from the destination reported seeing the aircraft pull-up into a very steep climb from an extremely low height with its wings level, and then become inverted. It then entered what was described by the witness as a spin or spiral dive, before impacting the ground in a near vertical descent. The pilot was found in the right-hand seat, and the passenger had been thrown clear of the wreckage. It was established that neither seat belt had been fastened at the time of the impact. Although it could not be determined which pilot was flying the aircraft at the time of the pull-up, medical evidence suggested that the pilot occupying the right-hand seat position was handling the controls at the time of ground impact. The weather at the time of the accident was fine and clear, with 10-15 knot winds. A thorough examination of the aircraft wreckage did not reveal any malfunction or mechanical failure which may have caused a sudden and severe loss of control. Investigation showed that at the moment of impact the aircraft was in a near vertical descent, without any rotation about the vertical axis, and the wings were in a stalled condition. No reason was found which could have explained either the low flying, or the steep pull-up. During the investigation it was established that with this aircraft type, a considerable degree of sustained elevator force would need to be applied by a pilot in order to achieve the type of flight path reported by the witness. It is considered that such a control input would need to be deliberately executed.

The pilot was spraying a banana crop, and swath runs had been conducted over a wire and some trees at one end of the field. On this particular run the pilot realised he was too low, and he attempted to fly under the wire. The left wing root was dented by contact with a tree and the wingtip was torn off by the wire. The aircraft remained under control and the pilot was able to effect a safe landing at his intended destination.

The pilot had been operating the aircraft on gypsum spreading operations in mountainous terrain during the morning. The task involved flying along a valley, crossing a ridge at the head of the valley and spreading the gypsum on the western slopes of the ridge. Shortly after the aircraft departed on the accident flight, smoke was observed rising from the valley. It was discovered that the aircraft had impacted the side of the valley with a high rate of descent and very low forward speed. The hopper load had not been jettisoned prior to impact and the hopper doors were closed. The aircraft was destroyed by impact forces and the subsequent fire. The investigation did not reveal the presence of any pre-existing mechanical defect which might have contributed to the accident. The engine was operating at high power at the time of impact. Because of the damage to the aircraft, the hopper and fuel loads were not able to be precisely determined. Evidence suggested that the aircraft was probably heavier than the maximum all up weight approved for agricultural operations. On previous flights the aircraft had been observed to orbit over the valley in order to gain sufficient height to safely clear the ridge. It is considered possible that on this occasion the pilot commenced the orbit from a position and height which did not allow sufficient room for the manoeuvre to be completed at moderate bank angles. It was evident that during the orbit the aircraft stalled and entered an incipient spin. Insufficient height remained to permit recovery before impact with the ground. The weather conditions at the time were conducive to the formation of downdrafts, but whether this phenomenon had any bearing on the loss of control leading to the accident was not established. In addition, the reason that the hopper load was not jettisoned could not be determined.

The pilot had not previously landed at the particular area, but had carried out a detailed inspection to ensure no debris was present in the water, which was about one metre in depth. Almost immediately after touchdown the nose yawed some 20 degrees to the left and the aircraft pitched forward and overturned. A subsequent inspection revealed considerable damage to the hull below the cabin floor. The investigation discovered that the right hand nosegear door had previously been damaged. The repairs carried out had not corrected weaknesses in the door resulting from this damage. The area selected for landing on this occasion was too short for normal operations, and discolouring of the water prevented the pilot from detecting any obstructions below the surface. The aircraft adopted a nose-low attitude shortly after touchdown, but whether this was pilot induced or the result of striking a sankbank was not established. The resulting pressure of water on the nose area distorted the already weakened gear door and forced the left door sideways into about the normal open position. During the subsequent yaw and overturn, the right wing and the nose of the aircraft struck the bottom of the river.

The pilot had flown the aircraft, without incident, a number of times prior to the accident flight. He made a full flap, normal approach to land after checking that the landing gear was down and locked. The wind at the time was a light crosswind from the left. Touchdown was normal, but immediately afterwards the right gear leg collapsed. The aircraft veered sharply to the right and the other gear legs failed. The aircraft slid to a halt on its lower fuselage. The strip had a transverse gradient of three percent down to the right. Witness evidence and ground markings confirmed that the touchdown was normal. Inspection of the damaged components of the right gear indicated that the initial failure had been from overload forces. No significant pre-existing damage was evident.

The pilot was engaged in the chemical spraying of several properties in the general vicinity of his own property near Gatton. After completing the spraying of two properties, the pilot began positioning the aircraft in order to spray his own crop. A witness observed the aircraft as it turned to the right and flew at low level beneath power lines across a highway. The aircraft was then seen to bank slightly to the right and strike another set of power lines on the opposite side of the highway. Two of the wires were broken and the third remained entangled with the aircraft. The aircraft struck the ground in an inverted attitude. The power lines struck by the aircraft had been erected about three weeks before the accident. They had been erected at the request of the pilot to service a portion of his property. He had flown under the wires on several occasions in the preceding three weeks.