Wirestrike

The pilot reported that a single power line was strung diagonally across the treatment area. A number of runs had been conducted under the wire. At about the mid-span of the wire between the supporting poles, the aircraft struck the wire. The wire deflector failed, allowing the wire to slip between the fin and rudder. The mass balance and the top of the rudder were severed, but the pilot maintained control and subsequently landed without further incident.

Circumstances:

The pilot was conducting spraying operations over a millet crop which was approximately 1.5 metres high. Towards the end of the spray run, the aircraft flew under two wires which were about 5.6 metres above the ground. Weather conditions were ideal with high overcast cloud and a light southerly wind. On the second spray run, the aircraft struck the powerlines. The aircraft's wire deflector cable was broken, and the wires then struck the vertical fin, one 50 millimetres from the top and the second 150 millimetres from the top. The wires then tore the tail fin off the aircraft, leaving the rudder trailing by its control cables. The aircraft was seen to pull up abruptly to a height of approximately 150 feet, turn left and head toward open paddocks one kilometre away. Shortly after, it descended rapidly into a crop about 300 metres short of open paddocks, coming to rest 19 metres from initial impact. Engineering examinations found that the elevators had been fouled by the trailing rudder. It is probable that the pilot experienced difficulties with elevator control, resulting in loss of control of the aircraft.

Significant Factors:

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

1. There was insufficient clearance between the crop and the powerline for the aircraft to safely fly under.

2. The aircraft struck the wires which resulted in the rudder trailing by its control cables.

3. The trailing rudder interfered with elevator control, probably causing the pilot to lose control.

The pilot reported that he was delivering the aircraft to the new owner. The normal strip at the property was unserviceable so the use of another strip had been arranged. No mention was made by the owner of a powerline crossing near the end of the strip. The aircraft struck the powerline on late final approach and fell to the ground tail first. This accident was not the subject of an on-site investigation.

Circumstances:

The aircraft was spreading superphosphate when it struck a powerline at a height of about 200 feet above ground level. The aircraft struck the line with the main landing gear legs, and although the wire slid up the cutting edges, it was not severed by the cutters but snapped near a pole supporting the span. The wire then slashed around the aircraft until it cleared itself from the airframe after which the pilot discovered that he was only able to turn the aircraft to the left. He carried out an immediate forced landing. The powerline was suspended across a gully via a 470 metre span. The pilot was aware of the line having flown over it on several previous occasions. The pilot stated that, as the line was extremely difficult to see, he had been judging his clearance by reference to the poles at either end of the span. At the time of the strike the pilot's attention was distracted by difficulty in starting the superphosphate running correctly and by concentration on three other sets of wires.

Significant Factors:

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

1. The power line that the aircraft hit was very difficult to see from the aircraft.

2. The pilot's attention was distracted.

Circumstances:

For several days, the pilot had been giving flying instruction to the aircraft owner operating from an airstrip located in a valley on the owner's property. The strip was aligned in an east - west direction with a downhill slope to the west. Wind conditions had been such that take-offs were being made towards the west with right hand circuits to the north so as to operate over the lowest surrounding terrain. The pilot was aware of a power line running from east to west parallel to the airstrip situated on a ridge about 700 metres to the north which the aircraft could remain well clear of while flying parallel to it on the downwind leg of the circuit. On the day of the accident the pilot had arranged to take another person for a familiarisation flight. The wind had changed to an easterly at about 10 knots, so the take-off was conducted uphill. This required a longer climb out before the pilot could commence a left hand circuit to again operate north of the airstrip. He turned onto the downwind leg when about 120 -150 feet above ground level at approximately the same distance from the airstrip extended centre line as before. The circuit area was now displaced to the east where unbeknown to the pilot the power line changed direction by about 20 degrees to the south. After turning onto the downwind leg, the pilot noticed the power line converging towards him from his right. Although evasive action was taken it was too late to prevent the right hand wing from contacting the power line resulting in loss of control and the aircraft dived into the ground. The pilot reported that the aircraft had been operating normally before colliding with the power line. This accident was not the subject of an on-scene.

Significant Factors:

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

1. The pilot had not made himself familiar with the location of the power line.

2. The power line was obscured by trees to the east of the airstrip.

3. The pilot failed to see the power line in time to prevent a collision.

The pilot was carrying out a "cleanup" swath run on a 50 acre potato crop which he had sprayed on the previous evening, but had not finished due to poor light. The cleanup run was conducted below a power line at right angles to the flight path and about eight metres above the crop. This power line was near another line which traversed the crop, and was at an angle of about 30 degrees to the flight path. The pilot was aware of the location of the second power line and had intended to fly over it after pulling up from the run under the first line. The run under the first line was completed, and when the pilot began to pull up, he noticed that the second line was closer than he had expected, and he decided to go under instead of over the line. During the manoeuvre, the right wing contacted the 3 strand 12 gauge steel wires, and the aircraft slid along the wires for some 200 metres before cartwheeling into the crop tail first. The aircraft then bounced upright and caught fire. The right wing had been severed by wire contact outboard of the wing strut supports prior to ground impact and the pilot had been sprayed with fuel. The pilot received burns to his right arm and left leg. He was wearing leather gloves, a short sleeved shirt and shorts under polyester and cotton overalls. He also wore a helmet. Despite the fact that the helmet was damaged during the accident sequence the pilot received no head injuries.

Upon arriving in the area to be sprayed, the pilot carried out an airborne inspection and located the obstacles, including a powerline beside a road just outside the eastern boundary. Three wheat paddocks adjoining each other were to be sprayed. The first spray run was about one and a half kilometres long in an easterly direction. During the run the pilot concentrated on the drift of the herbicide spray and forgot about the power line. He saw the wires a split second before impact. The aircraft struck the north/south power line and severed one of three wires before crashing inverted into the ground about 80 metres beyond the road. Weather conditions at the time were fine and ideal for spraying. This accident was not the subject of a formal on scene investigation.

The pilot had completed his last spray run and had pulled up into a procedure turn to make a clean-up run. He was aware of two power lines, one running parallel to the spray run and the other at an angle to the first. He was intent on avoiding the line at an angle to his run but struck the other as he positioned for the clean-up run. Visibility at the time was reduced in light rain. The line hit the right wingtip and windshield wirecutter. Thw wirecutter bent under the load and the wire broke the windscreen and tore off the top of the cockpit before it separated. The pilot was able to recover the aircraft without further damage.

The pilot was to spray weeds in four areas marked 1-4 on the plan of the property he had been given. He conducted an airborne inspection during which he noted a single power line, running east west, along the northern side of area 1. Adjacent to the power line was an area of seed lucerne which the property owner emphasised was not to be sprayed. Area 1 was immediately south of area 2 while areas 3 and 4 were some distance away and well clear of the power line. There was sufficient daylight remaining for the pilot to spray areas 3 and 4 and to partially complete area 2 flying runs parallel to the wire. That evening, there was some disagreement between the pilot and the property owner as to whether the correct ratio of chemical had been used, and the property owner again emphasised that he did not want any spray to fall on the seed lucerne. The following morning, without conducting a further aerial inspection, the pilot sprayed the remainder of area 2 and, while waiting for the markers to position themselves in area 1, he decided to do a clean-up run from north to south along the western edge of area 2. He recalled that, as he flew the run, foremost in his mind was the need to avoid spraying the seed lucerne. The aircraft struck the power line at the completion of this run. The wires became caught in the engine upper cowl and rolled the aircraft so that it impacted the ground right wing first. The right wing was torn from the fuselage as the aircraft cartwheeled. The pilot, who was wearing a helmet, received serious facial injuries in the accident. It was found that the left hand lap toggle in the safety harness buckle had failed on impact, allowing the pilot to be thrown forward and to the right into the instrument panel/coaming. Metallurgical examination showed that the toggle failed due to insufficient strength caused by inadequate heat treatment during manufacture.

The pilot was carrying out his first cross country flight over unfamiliar terrain. After passing over one of his planned turning points he became concerned about the aircraft's location and decided to follow a road back towards the destination. Enroute the pilot descended the aircraft to read a road sign in an endeavour to establish his location. However, the aircraft struck a power line and subsequently collided with the ground. This accident was not the subject of an on-site investigation.