The pilot had flown the aircraft from his base to the property strip earlier in the morning. The aircraft was loaded with 375 kilograms of a pelletised material called "Grassland" for spreading. The performance of the aircraft up to this time had been normal. The pilot reported that the initial part of the takeoff run appeared normal. However, as the aircraft approached the end of the strip, he became aware that the airspeed was about 10 knots below the desired speed. The aircraft became airborne, struck some small trees, and continued to lose performance before coming to rest about one kilometre from the end of the strip. Examination of the aircraft determined that the engine compression was low and that one cylinder was cracked. No positive reason for a sudden reduction in performance on this takeoff was found. The pilot reported that he had not thought about dumping the load as he was busy flying the aircraft and trying to maintain control. The product was expensive and the pilot's actions indicated that he might have been concerned about the commercial implications of dumping the load.

The pilot reported that after he had hand started the engine, the aircraft rolled forward and the nosegear struck a concrete culvert.

Circumstances:

The aircraft was observed to take off normally and climb to about 200 feet above ground level. Shortly after passing beyond the end of the strip, an apparent change in aircraft engine noise was heard by witnesses. The aircraft was then seen in a steep nose-down, inverted attitude. It remained in this attitude until ground impact. On site examination showed that the aircraft had struck the ground in an inverted nose-down attitude of 35 degrees. No fault was found in the aircraft or its systems which might have contributed to the accident. The engine was operating at impact. Witnesses reported that the pilot had complained of chest pains both on the morning of the accident and the previous evening. The postmortem report on the pilot indicated that, if other causes of the accident were excluded, there was sufficient chronic heart disease present for sudden heart failure or sudden death to have been likely events.

Significant Factors:

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

1. The pilot probably became incapacitated during flight, causing control of the aircraft to be lost.

The pilot had experienced a smooth flight and after checking the wind direction positioned the aircraft on the downwind leg for a normal circuit. He reported that after reducing speed he lowered one stage of flap and then selected the landing gear down. He believed that he also checked the gear indicator on final approach and saw three green lights. The speed on final was reported as about 80 kts with a power setting of 16 inches and full flap. After round out power was reduced to idle and the pilot then sensed that the aircraft was settling further than usual. When the propeller began striking the runway the pilot pulled back sharply on the control column and applied full power. The aircraft failed to respond as expected and the pilot turned to the left away from the strip. Shortly afterwards the aircraft mushed into the ground. Ground witnesses reported that the aircraft made an approach with the gear up and that the gear began to extend when the pilot pulled up in his attempt to go around. The aircraft gear was fully or partially extended on impact and the main legs were torn off. The aircraft came to rest some 300 metres from the centreline of the runway. Initial on-site inspection could not find any reason for the failure of the gear to extend and showed that the gear warning horn was operable.

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.