Wirestrike

ACFT STRUCK TWO POWER LINES ON FINAL APPROACH WITH PROP.ONE WIRE SLID UP WINDSCREEN & SLICED OFF CANOPY ROOF.OTHER SNAGGED LDG GEAR & TILTED ACFT TO VERTICAL NOSEDOWN ATT.HIT GND,OVERTURNED & BURNED.

PLT WAS NOT TRN FOR PWR LINE INSPECTIONS.AN APPROVED PLT INSTRUCTED HIM NOT TO FLY BELOW 300 FT.LATER ACFT WAS OBSERVED OVERFLYING PWR LINES AT 100 FT & 25 FT JUST PRIOR TO ACFT STRIKING PWR LINES.

WHILST ENGAGED IN KANGAROO CULLING OPS ACFT STRUCK POWER LINE & CRASHED.PLT FLD TO EXERCISE NECESSARY DEG OF VIGILENCE REQ IN LOW LEVEL OPS AS HE WAS AWARE OF LINE HAVING OVERFLOWN IT EARLIER IN DAY.

ACFT STRUCK A TWO WIRE POWER LINE WHILST LOW FLYING,THEN STRUCK GROUND NOSE DOWN AND CARTWHEELED

ACFT STRUCK PWR LINE DURING CLEAN UP RUN ALONG EDGE OF CROP-CRASHED AND BURNED-WIRE AND CROP DAMAG

VH-BOA was one of two aircraft operating from an agricultural strip near Namban. The strip was orientated approximately north/south and the agricultural load, a mixture of superphosphate and clover seed, was located at the southern end. Weather conditions were fine with a light surface wind from the south-east. Prior to commencing operations it was agreed between the two pilots that VH-BOA would treat the areas to the east of the strip whilst the other aircraft worked to the west. The possibility of expediting operations by VH-BOA had not previously landed on this area but he had inspected, on the previous day, the surface which in the northern section of the area, he did not detect a 260 metre long double wire span in the southern sector which crossed the approach path at an angle of 30 degrees. At the completion of their first spreading flights both aircraft returned to the strip at the same time. The pilot of VH-BOA then decided to land on the alternative area. An immediate approach to land from the south was commenced. The pilot's attention was primarily directed towards sighting a slight contour bank which he knew bordered the cleared area. The aircraft was at a height of about 20 feet and an airspeed of some 55 knots when it struck the power line. One wire broke but the other caught under the right door latch. The aircraft rapidly decelerated and fell to the ground.

After the interim completion of agricultural spraying operations, the property owner asked the pilot to disperse one load of insecticide over a neighbour's property. The adjacent property owner had requested this work to be done. As the pilot hover-taxied an Agusta-Bell 47G-3B1 helicopter towards a water replenishing point on the neighbour's property, the cockpit bubble and one main rotor blade of the helicopter struck an unseen single strand high-tension power line partially concealed by a shed. The pilot was able to maintain control of the helicopter and landed safely. The helicopter sustained minor wire impact damage to one main rotor blade, the main rotor mast, and one tail rotor blade. The pilot and passenger escaped without injury. The water tanks were near a shed which partially concealed the wire which was at an angle of about 45 degrees to a height of 60 to 70 feet AGL. The wire also blended into the background foliage. The pilot had visited this section of the neighbour's property about 2 years ago. No wires were noted during this visit. The owner of the adjacent property had not briefed his neighbour to inform the pilot about a new wire that had been erected near the water tanks. Consequently, the pilot had not been adequately briefed by the other property owner as to the presence and location of the recently erected wire which was in close proximity to the water tanks.

The operator and pilot reported that the helicopter struck a single-wire-earth-return (SWER) power line at the beginning of a swath run during a spraying operation. The orientation of the cane paddock being sprayed was north-east / south-west with a major power line running through the north-eastern corner. A SWER power line running east -west joined the main power line over the paddock. The pilot had sprayed the western edge of the paddock, flying the helicopter over the main power line on each spray run. As the pilot moved his spray effort further east on each swathe run, he concentrated on missing and flying over the main power line. On one pass he lost awareness of the SWER line and during descent onto the crop the mast of the helicopter struck the line. The helicopter rolled into the crop. The pilot was not injured

The pilot of the Hiller 12E helicopter had been tasked with spraying insecticide on a paddock of soybean plants. The pilot familiarised himself with the property layout and obstacles before starting treatment of the area. The paddock to be sprayed was crossed at its mid-point by powerlines running east-west. The southern boundary of the paddock was marked by a wire fence, a road and another set of powerlines.

The pilot reported commencing a spray run along the northern boundary but found that his GPS navigation system was not working. He landed on the western side of the paddock to re-enter data into the GPS system. On carrying out another run, the pilot found the system was still not operating, so he moved the helicopter away from the paddock to the south. He then elected to return to the paddock by flying over the powerlines. The pilot reported that at this time, he was mentally occupied with the problem with the GPS and forgot about the powerlines at the southern edge of the paddock. The helicopter spray gear contacted the powerlines, causing the helicopter to pitch nose down and contact the ground. The helicopter came to rest inverted, and the pilot climbed out of the wreckage, receiving only minor injuries. The helicopter did not catch fire.

A significant factor in this accident was the preoccupation of the pilot with the GPS navigation equipment at a time when he was flying close to obstacles.

FACTUAL INFORMATION

The aircraft was involved in aerial spraying operations. The pilot was preparing to do a clean-up run along the edge of a paddock on a heading of approximately 135 degrees. He initially flew due west alongside a powerline. He then turned right to fly under the powerline and return to begin the clean-up run. While approaching the start of the clean-up run, the pilot's attention was focussed on the east-west powerline which he was to again fly under. Before reaching that powerline, the pilot suddenly saw another wire immediately in front of him. He pushed the yoke hard forward to minimise the damage to the aircraft, but the powerline hit the tail area. The aircraft deviated towards the ground before he was able to regain control. The top third of the vertical stabiliser had been removed and the rudder destroyed. Even though directional control was severely affected, the pilot was able to fly the 10 NM back to the airstrip and land without further incident.

The pilot reported that the property owner had briefed him on the location of four powerlines in the area, including the powerline he had flown under. He did not brief the pilot on the powerline that was hit. The pilot stated that the property owner appeared to assume that he knew the location of all the relevant powerlines as he had sprayed in that area a few weeks prior to the accident.

The pilot reported that the powerline was difficult to see as it was not marked and the weather conditions were overcast. It was a clear span powerline between a post located amongst some trees and a shed.

ANALYSIS

The pilot was not aware of the location of the powerline which the aircraft impacted at the commencement of a spraying clean-up run. Although the pilot had been informed of four other powerlines in the area, he had not been briefed on, or noticed, this particular powerline. The clear span wire would have been difficult to detect as it was not marked, was observed against an overcast background, and the post was located amongst trees.