Wirestrike

The pilot was making a landing approach, to an area not normally used for helicopter operations, at the conclusion of a stock mustering operation. The helicopter collided with a single wire telephone line then landed heavily, rolling onto its side as the skids collapsed. The pilot reported that the wire was normally difficult to see because of age discolouration and the long span between poles. On this occasion he had forgotten that the wire ran through the area and did not see it during the approach. This accident was not the subject of an on-site investigation.

After completing the first swath run the pilot climbed the aircraft over a single set of power lines. At the end of the second run the aircraft was flown under these wires. When the pilot then commenced a climb he observed a second set of wires, he attempted to fly the aircraft under them but the canopy of the aircraft struck the wires. The aircraft remained airborne, however, by using the rear vision mirror, the pilot saw that the fin and rudder were extensively damaged. Rather than risk a loss of control situation he landed the aircraft in a field of tall sugar cane. Prior to commencing the task the pilot was given a map of the area by the property owner. The map was marked with the area to be sprayed and also had indicated, by the use of crosses, a power line at the end of the spray run. The pilot assumed that these crosses indicated only one set of wires. Being anxious to complete the task he did not carry out a reconnaissance before commencing to spray.

Circumstances:

The pilot reported that he had flown into the landing area earlier in the day and had noted the position of a power line. On the accident flight, he approached to land from a different direction and encountered another wire which he had not been aware of. He lost control of the helicopter when a main rotor blade contacted the wire.

The pilot had operated into the strip two weeks prior to the accident flight, and saw a powerline that had apparently been diverted underground, near one end. After checking with his passengers who were familiar with the area, a landing was made. On this flight a flatter approach was made and the nose leg snagged on the powerline causing the aircraft to impact the ground in a steep nose down attitude. The 10 metre high powerline had been diverted to cross the approach area, above ground, 274 metres from the threshold.

Circumstances:

The pilot reported that he encountered windshear on final approach. He had made allowance for the gusty turbulent conditions and was approaching with full power when the aircraft began to sink towards a power line which was strung across the approach path. The pilot stated that he managed to avoid the wire with the main wheels, but the tailwheel struck the wire and arrested the forward motion of the aircraft. The aircraft then crashed to the ground from a height of about 50 feet. The pilot was aware of the presence of the wire on the approach path prior to the accident.

Significant Factors:

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

1. The pilot encountered windshear.
2. The pilot was unable to avoid a power line on final approach.

Circumstances:

The helicopter collided with powerlines whilst engaged on a pig spotting flight.

Information provided by the pilot indicated he had planned to land the aircraft in a paddock used by crop dusting aircraft. He contacted the owner of the paddock and determined that it met the requirements for his aircraft. The pilot was advised that a set of powerlines crossed the approach end of the paddock and he requested the owner to park his car underneath these powerlines to mark their location. When the pilot arrived over the strip a car was parked near the approach end where the pilot thought the powerlines were and he assumed the owner had acted on his request. After carrying out an Authorized Landing Area inspection during which he did not sight the powerlines the pilot made a normal approach. He kept well clear of the car but the aircraft collided with the powerlines on late final approach and touched down heavily. Information provided indicated that the owner of the paddock had parked his car more than 20 metres downwind of the powerlines for reasons which were not determined and this had given the pilot the wrong impression of their location. This accident was not the subject of an on scene investigation.

Following a period of circuit practice, the instructor was demonstrating some enroute emergency procedures. An autorotation was entered from 2000 feet, with the pilot aiming for a paddock on the side of a river. He advised that descent was continued to about 250 feet above the ground. Shortly after power was re-applied the helicopter collided with a set of power lines and dived to the ground. The pilot had noted two other sets of wires in the area, but had not sighted a set of three cables between the others until immediately before the collision. The helicopter was being operated outside the designated training area. The grey oxidised powerlines, which were estimated to be between 80 and 100 feet above ground level, were very difficult to see against the overcast sky conditions. The span between supporting poles was greater than those between the other sets of cables.

The pilot was engaged in spraying a small crop of tomatoes. This was the first time he had sprayed this paddock. The farmer provided him with a map of the area to be sprayed, but the powerlines were not marked on the map, so a briefing was conducted on the location of the powerlines. There was a set to the north of the paddock and two sets to the south. Before he commenced spraying, the pilot conducted an aerial inspection of the area. During the aerial inspection he was in radio contact with the farmer and believed he had located all the powerlines. Shortly after commencing the job, the pilot manoeuvred the aircraft for a run in the northerly direction. His intention on this run was to fly below a powerline that on previous runs, because of the disposition of that particular line, he had flown over. When manoeuvring to fly below this line, the aircraft hit another line 80 metres to the south. The pilot was not aware of the presence of the line the aircraft struck. The aircraft hit the ground and was destroyed by the impact and the resulting fire. The briefing received by the pilot was inadequate.

The pilot had completed a pre-flight inspection, when he received a message to the effect that there was an unfamiliar vehicle in the vicinity of a new farm piggery, about 2 km from the strip. He boarded the aircraft, which shortly afterwards was seen to take-off and fly at low level towards the piggery. A farm employee at the piggery observed the aircraft approaching in straight and level flight and with normal engine noise. The aircraft then began to turn to the left, but struck a recently erected single wire power line at a height of 23 feet above the ground. The left wing tip and one propeller blade were severed and the aircraft cartwheeled to the ground. No defect or malfunction was subsequently discovered which might have affected the pilot's ability to safely control the aircraft. It was considered probable that the pilot was concentrating on locating and identifying the vehicle near the piggery, to the extent that he overlooked the presence of the power line. Notwithstanding the above, the reason the pilot chose to fly at such a low height could not be determined.