Wirestrike

The helicopter had been chartered because the passenger's farm had been isolated by flood waters. The crew carried out a survey of the area before landing to check the suitability of the chosen site. Shortly after take-off, the aircraft collided with a power line which was about 25 feet agl, and then struck the ground heavily about 15 metres beyond the line. Both the pilot and the crewman reported that they had sighted the power line during the survey prior to landing. However, the pilot subsequently forgot the presence of the line and conducted a shallow climb after take-off. Because the rear seat cushions were wet, the passenger was placed in the front seat, while the crewman occupied a rear seat. When he became aware that the helicopter was climbing at a shallow angle, he reminded the pilot to beware of the wires. The pilot then saw the power line directly ahead of the aircraft, but was unable to avoid the collision.

The pilot was engaged in spraying an area of grape vines. On the final spray path the aircraft had to pass under a set of power lines. The pilot reported that as the aircraft approached the power lines, it was affected by an updraught. He pushed the control column forward but the propeller and fin mounted wire deflector struck the power lines. The aircraft descended and struck a post used to support the vines before it came to rest in the crop. The pilot was inexperienced in agricultural operations. The final spray run involved a difficult task in that several obstacles had to be negotiated. It is probable that the aircraft was affected by a willy willy and that the pilot was unable to fully regain control of the aircraft before it struck the crop.

At the conclusion of an aerobatic display the pilot performed an inverted circuit, rolling upright as the strip was sighted on final. On short final the aircraft descended below the desired flight path and the pilot applied power. The aircraft responded but the right gear leg caught on a power line 5 metres agl and 330 metres from the threshold. The aircraft struck the ground in a steep nose down attitude and came to rest inverted. The inverted circuit had been conducted at between 50 and 100 feet above the tops of the trees.

The pilot was inspecting areas of noxious weeds to check on the results of recent spraying. The helicopter struck a power line which severed the bubble windscreen. The wire then contacted the pilot's throat before being cut by the main rotor. The helicopter struck the ground tail rotor first about 35 metres beyond the point of collision. After extricating himself from the wreckage, the pilot swam across a river, walked 3 kilometres to a homestead and drove 15 kilometres for help. He was later admitted to intensive care in hospital. The pilot had been informed that there were power lines in the area, but was unaware of their precise location. He had conducted a survey flight prior to commencing the spraying operation, but had not sighted the particular cables. There was evidence to indicate that the helicopter had flown under the cables on at least one occasion while spraying. The cables, which spanned a river, were supported by poles which were 253 metres apart and which were probably outside the pilot's normal field of vision.

The aircraft was engaged in defining swarms of locusts as part of a control programme. The helicopter was being flown at about 35 feet above ground level, when one of the main rotor blades struck a powerline. Control of the aircraft was lost and it struck the ground in a nose down attitude, 111 metres beyond the powerline. The pilot had flown over the area earlier in the day, but had not sighted the wire. On this occasion he did not make a specific search for wires before commencing the low level operation. The span of wire between the support poles measures 610 metres and although the support poles were easy to see, the wire was not. The pilot was not aware that the helicopter had collided with the wire until some time after the accident.

Spray runs were being carried out under a power line when the aircraft cable deflector struck the line. The cable rode up the cable deflector and severed the top of the rudder from the aircraft. The aircraft was landed in a paddock without further damage.

On commencing the clean up run, the wire deflector on the aircraft struck a single power line. The top section of both the fin and rudder were severed from the aircraft which was subsequently landed at the DEPARTURE strip without further damage. The pilot had been briefed on the crop to be sprayed and on the location of power lines in and around the paddock. After cleaning up the other edges, the final run was commenced with the aircraft flying parallel to the main power lines. The pilot temporarily forgot the presence of the single wire running from the main line into the paddock.

The pilot was very experienced, having been an agricultural pilot for a considerable number of years. He had been aerial spraying a paddock for weed prevention with a herbicide, flying in a south to north direction, and passing under power lines which crossed the paddock from east to west.

The aircraft was observed to strike the power lines with the tip of its fin, causing the empennage to separate from the fuselage. The aircraft then dived into the ground approximately 50 metres beyond the power lines, bounced back into the air and slid for another 47 metres with the engine, propeller and right hand fuel tank separating from the aircraft. The fuel tank exploded and set fire to the grass on the steep slope of a creek bed, next to where the aircraft came to rest. The pilot received minor injuries as a result of the impact, but was able to remove himself from the aircraft without help. He then slipped on the steep angled wing-walk and fell into the fire, receiving severe burns to the areas of arms and legs not covered by clothing. There was no medical evidence indicating that the pilot had been effected by the herbicide before the accident. This type of aircraft has been the subject of many wire strikes to the fin, as it is higher than the propeller arc in level flight, and pilots can misjudge its position.

This occurrence was not the subject of an on-site investigation.

Circumstances:

The pilot was expecting to make an early morning DEPARTURE but was confronted with adverse weather conditions and low cloud. He was advised by another pilot that these conditions were expected to improve later that morning, but he decided to depart immediately and assess the weather as the flight proceeded. After flying in a westerly direction for several minutes it became obvious to the pilot that visual flight could not be maintained, so he elected to return for a landing. Re-entering the circuit area the low cloud and poor visibility required the flight to continue close to the ground, and the pilot misjudged the turn onto final. He abandoned the landing and joined a low left hand circuit for the reciprocal runway. While turning onto a close final leg, the left hand wing contacted a six metre high telephone wire located across the approach path approximately 300 metres from the runway threshold, causing the aircraft to lurch violently to the left and impact the ground heavily.

Significant Factors:

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

1. The flight was initiated and continued in adverse weather conditions. This accident was not the subject of an on-scene investigation.

The helicopter was being used to spot cattle. During what was apparently the first sweep of the area, the helicopter passed over the crest of a ridge and collided with a single power line. The angle between the fore-and-aft axis of the helicopter and the wire was approximately 40 degrees. The helicopter slid along the wire before the tail boom and then the tail rotor contacted the wire. The helicopter came to rest in a nearby gully. No fault was found in the aircraft powerplant or systems which might have contributed to the accident. Neither the pilot nor the passenger had conducted spotting operations in the area previously, and there was no evidence that either was aware of the position of the wire. It is likely that the helicopter crossed the ridge at a very low level and approximately 40 metres from a power pole carrying the wire. Background vegetation and overcast conditions may have made it difficult to distinguish the wire and power pole.