Wirestrike

The helicopter was tasked to sling load two large metal hooks between two points on a wharf. The first hook was off-loaded, but as the helicopter was lifting the second hook, the tail rotor contacted a solar panel at the top of a light pole. Control of the aircraft was lost and it was observed to perform a nose high turn before striking the water. The helicopter floated inverted and the pilot was able to evacuate himself and swim to a boat. It is considered likely that while concentrating on the position of the load, the pilot diverted his attention from the operation of the helicopter and allowed it to descend, which resulted in the tail rotor strike.

The pilot was spraying a pea crop in calm conditions. A high voltage powerline was strung above a fence bounding one side of the paddock being treated. The pilot knew of its presence and could see it clearly during the spray runs. At the end of the sixth run prior to making the procedure turn, the pilot felt a slight jolt and was surprised when he saw the powerline collapse. The aircraft's deflector wire contacted the powerline and guided it over the fuselage until it was severed by the deflector wire rear attachment bracket on top of the fin. The pilot advised that he misjudged the clearance between the fence and the powerline and later inspection revealed that the line was hung lower than is usually the case.

During a spray run which involved flight beneath a power line, the pilot lost sight of the supporting poles and assumed he had passed the cable. A pull up was initiated but the fin and rudder struck the cable, which tore about 15 cm from both surfaces. The aircraft remained controllable and a safe landing was subsequently carried out.

Circumstances:

The pilot was spraying a paddock which required the aircraft to fly over a main power line near the southern boundary. At the completion of a spray run, the aircraft collided with and severed the top three cables of the main power line. The pilot decided to return to Quirindi to land and inspect the aircraft for damage. Before landing, all checks were completed including a functional test of the brakes. The landing was normal until the latter part of the landing roll when the aircraft commenced to veer to the left. The right brake failed as the pilot attempted to correct the swing. The aircraft ground looped, during which the right main gear leg and right flap were damaged. During the wire strike, electrical arcing had burnt a small hole in the right brake line. Although the right brake tested normally prior to landing, brake fluid escaped from the hole during heavy brake application on the landing roll. This report is based on information provided by the pilot.

Circumstances:

The pilot had been airborne for approximately 15 minutes, carrying out aerial spraying of a newly planted crop. The paddock being sprayed was bounded on its northern and western boundaries by a fence approximately 1.2 metres high. Directly above, and running parallel with the western fence, was a three strand power line, the lower cables of which were approximately five metres above ground level. The pilot had flown above the power lines on each previous spray run, crossing the paddock from east to west. After completing a procedure turn the aircraft was lined up for the clean-up run from west to east. The pilot stated that he forgot about the power lines until they became visual again at close range. Knowing he would not be able to climb the aircraft above the cables in the distance remaining, the pilot elected to fly between the lines and the fence. The aircraft struck the two lower cables of the power lines, tearing the fin and rudder from the airframe. The aircraft continued airborne for approximately one kilometre before rolling to the right and striking the ground. It then began to break up as it cartwheeled across the paddock, finally coming to rest inverted. An inspection of the area revealed that the poles that supported the power lines would have been difficult to see, when approaching from the west, as their outline merged with trees in the paddock.

Significant Factors:

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

1. The pilot forgot about the presence of the power lines.

2. The pilot did not see the power lines in time to avoid them.

3. The aircraft wire deflector failed on contact with the power lines.

The purpose of the flight was to film a moving train. Prior to commencing the operation, the pilot made an aerial inspection of the area and mentally noted the various obstructions. On the second filming run the helicopter collided with power lines at a height of 33 feet above ground level. The helicopter descended and struck the ground about 50 metres beyond the point of collision. It then bounced and came to rest on its side. The pilot was highly experienced in aerial photography and survey operations. At the time of the accident, visibility was reduced to less than 2 kilometres in light rain. One of the poles supporting the power lines was hidden from the pilot's view by a large tree. It was also possible that the pilot had flown outside the area he had previously inspected, as he had not been aware of the presence of the particular set of wires.

Circumstances:

The pilot stated that whilst aerial mustering he attempted to push a beast out from under a bush. The beast ran out from under the bush but headed away from the main mob. The pilot was attempting to turn the beast back towards the mob, when his passenger warned him of a power line which was in close proximity to the aircraft. The pilot stated that he flared the aircraft abruptly to try and avoid the power line, but the aircraft then began to sink, and the main rotor struck the power line. The aircraft then struck the ground heavily after falling about 30 feet.

Circumstances:

At the completion of a cross-country flight, the pilot attempted an out landing on a cleared area about 1 kilometre north of the aerodrome boundary. The approach path was in a southerly direction and took the glider between two large hangars, which were off the aerodrome. Powerlines which the pilot did not see, ran east west beside a road between the hangars and the outlanding field. The glider collided with these powerlines, separating the tailplane from the fuselage and the canopy was shattered.

The helicopter was being used as an airborne filming platform. It was being flown at about 30 feet above ground level along the side of a roadway, while the film crew filmed a bus that was travelling along the road. The helicopter was observed to gain altitude and pass over a power line then descend again to 30 feet above ground level. After travelling a further 500 metres the helicopter struck a spur line running from the main power line, pitched nose up before descending out of control and colliding with the ground. The wreckage slid 50 metres before coming to rest on the road. The positon of both the sun and the support poles of the spur line would have made detection of the line difficult unless the pilot had prior knowledge of its position. The pilot was not seen to conduct a survey of the area for obstacles prior to commencing low level operations. The task required the pilot to concentrate on the bus to the right of the helicopter as well as the flight path ahead. Examination of the wreakage did not reveal any malfunction which may have contributed to the occurrence. It appeared that on impact with the spur line one cable contacted the bottom of the windscreen pillar and the other became entangled in the rotor blades. All significant damage to the aircraft appeared to have resulted from ground impact.

Circumstances:

Following a similar wire strike accident to another company aircraft earlier in the day, a second pilot and aircraft were brought in to complete the spraying task. The second pilot had flown 30 hours on agricultural tasks during the three weeks leading up to the accident. For approximately nine months prior to resuming agricultural operations, the pilot had been engaged in fish spotting operations. During an aerial survey of the treatment area the pilot observed a 19kV Single Wire Earth Return (SWER) powerline running south to north across the property's northern boundary. The span between support poles was 860 metres. At the property owner's request, the Electricity Trust of SA (ETSA) had attached marker flags to that portion of the powerline above the owner's property. Following the survey, the pilot laid a smoke trail to ascertain wind speed and direction. The wind was evaluated to be a light south westerly. The pilot had intended to use the flags on the powerline as visual markers to indicate his passage beneath the powerline. Spraying started along the northern boundary flying east to west with the pilot pulling up into a right turn before the SWER powerline. On completion of the second run to the west, and while the aircraft was above trees in the adjacent property, the pilot was unable to sight the flags on the wire to the south of the aircraft flight path. With the flags unsighted, and no positive ground marker to indicate wire passage, the pilot, estimating that he had under flown the wire, pulled up into it. The aircraft struck the powerline with the left wing and windscreen cable cutter. The aircraft slid along the powerline and rolled over the top to impact the ground in a steep nose and left wing down attitude. The pilot evacuated the aircraft unassisted. Post ground impact fire destroyed the aircraft.

Significant Factors:

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

1. The pilot lacked recent flying experience in agricultural operations and below obstruction height flying.

2. The presence of marker flags on the powerline deceived the pilot into thinking that he could rely on these flags as wire passage markers.

3. The pilots survey of the property was inadequate. Specifically, he failed to mentally note the location of the powerline in relation to the ground topography, and being unable to select a positive ground feature had failed to arrange for a marker on the ground to give visual indication of wire passage.

Recommendations:

1. That the Civil Aviation Authority give consideration to reducing the calendar period for the flight test nominated in Civil Aviation Orders section 40.6 para 11 from 12 months to 90 days.

2. That the Civil Aviation Authority specify a syllabus for, and the qualifications of the person conducting, agricultural proficiency checks in accordance with Civil Aviation Order 40.6.