Wirestrike

The pilot advised that the paddock was sprayed in north south runs starting on the eastern side and progressing to the west. After completing the north south spray runs the pilot did not orbit the paddock and re-familiarise himself with the hazards before commencing the clean-up run.

Before reaching the end of the clean-up run, he remembered a power line that he was approaching. He pulled up but the main landing gear struck the power line. The aircraft rapidly slowed and the power line broke. The aircraft then crashed through trees and hit the ground.

Significant Factors

The following factors contributed to the development of the accident:

1. The pilot did not re-familiarise himself with the hazards in the paddock, prior to commencing the clean-up run.

2. The pilot forgot about the existence of a power line until it was too late to avoid it.

The pilot had been spraying the paddock all morning and, for nearly four hours, had been crossing a set of wires running across the field almost at right angles to the aircraft's flight path. On the third run of the fifth load for the day the aircraft's main wheels contacted the top wire of a two wire set, and the forward motion was arrested causing the aircraft to impact the ground.

During the ground impact sequence the pilot was thrown from the aircraft when a seat belt anchor point failed due to corrosion. The pilot had no recollection of any events during the day of the accident. Determination of the actual position of the wire was possibly made more difficult by the wire and one of the support poles tending to blend into the background. A possible contributory factor was that the pilot's concentration may have been reduced due the death of a relative the day before the accident.

The aircraft took off in company with another Cessna 152. Whilst turning to avoid higher terrain north of Kooralbyn, the pilot lost sight of the other aircraft against the setting sun. He rolled his aircraft to maintain physical separation from the other aircraft. In the process he lost control of his aircraft.

The pilot next noticed the ground rushing up to meet him and rolled off bank and pulled back on the elevator control. The aircraft passed underneath a powerline and the left wing tip struck the lower of the three wires. The collision with the wire caused the aircraft to flick roll through approximately 180 degrees. The aircraft narrowly missed the ground and trees before the pilot regained control.

Despite the obvious visual damage and control difficulties the pilot elected to fly the aircraft to Archerfield. An emergency was not declared, and the aircraft was landed safely at the destination.

Post flight inspection revealed that about one and a half metres of the leading edge was stripped of the metal skin back to the front spar.

The pilot was not endorsed to fly in formation with other aircraft.

The pilot, returning to his home base, decided to conduct an inspection of the paddocks around a property with which he was familiar. He completed two higher level circuits before selecting a suitable landing area. He had noted wires along the edge of the chosen paddock and elected to conduct an approach and a low-level inspection. After satisfying himself that the approach and landing area were suitable, the pilot commenced a missed approach with the intention of continuing the flight to his destination. He planned to return by car to inspect the paddock at ground level for suitability at a later date. As the pilot applied power, the landing gear caught on a wire across the paddock. The wire, which had a span of 400 metres, did not break immediately and the aircraft was pulled to the ground.

During the low level inspection, the pilot had removed his shoulder harness so that he would have a better view of the edges of the paddock as he flew along it. In the ensuing impact, he suffered serious injuries which were considered to have been potentially fatal, because of the lack of upper body restraint.

The pilot reported that he was mustering a herd of cattle and that he was aware of a powerline on the far side of the herd. Without realising that he had crossed the powerline in timbered country, he descended the helicopter in open country to turn the cattle. As he was pulling away from the herd, the skids of the helicopter struck the powerline. The main rotor struck the tail boom and the pilot lost directional control. The pilot closed the throttle and the helicopter landed heavily.

The search and rescue helicopter was called out to a potential rescue and medical retrieval of a man who had fallen from a waterfall at Barrington Tops which is a mountainous/wilderness area. Due to extensive cloud cover, approaching last light and a lack of contact with ground personnel, the pilot-in-command elected to land near Barrington Guest House. 900 metres south-east of the guest house was a paddock apparently suitable as a helipad.

While flying a right downwind leg at about 60 knots and 500 feet in very light drizzle, the pilot and crew/passengers searched for powerlines and other potential obstructions. Powerlines parallelling the intended landing direction were seen. One of the crewmen searched for wires by looking out through the only sliding door fitted, which was on the left side of the helicopter. A normal approach was flown. When the helicopter was about 20 knots and 25 feet above the ground, the crewman sitting in the left front seat suddenly detected a spur line running across the approach path. He called out a warning to the pilot, but it was too late. The helicopter struck two wires. The pilot immediately lowered the collective in an attempt to land as soon as possible. The landing was heavy. The helicopter impacted the ground in a slightly nose down attitude while banked slightly to the left.

The wire strike was at the level of the rotating swashplate. Cyclic control was probably lost when the control rods above the swashplate were damaged by the wires.

The spur line was particularly difficult to see. Rising ground ahead of the wires, in the direction of landing, camouflaged the wires. The pole at the end of the spur line was somewhat hidden by trees and light drizzle reduced visibility.

A wire strike protection device was not fitted on the helicopter.

SIGNIFICANT FACTORS 

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

1. The powerline was particularly difficult to see because of its location, the surrounding terrain and foliage.

2. Visibility was reduced due to light drizzle.

The helicopter was engaged in spraying herbicide along levee banks. The pilot tracked the helicopter along the top of the banks to minimise spray drift onto adjoining cotton crops. It was necessary for the pilot to look monetarily behind the helicopter to check the spray drift. On looking forward the pilot noticed power lines immediately in front of the helicopter under the rotor disc. He said there was no time to take evasive action. After the collision with the power lines, control of the helicopter was lost and it impacted the left side of the levee bank.

The pilot reported that during the descent into Fitzroy Crossing he diverted to inspect a fishing pool. During the inspection the descent continued unnoticed, and the aircraft collided with an object, later identified as a power line. The aircraft continued to operate normally and landed safely at Fitzroy Crossing.

Circumstances:

The aircraft was observed to land about halfway along a 490 metre long north-south grass strip. It became airborne again and appeared to climb slowly before veering left and disappearing from view behind trees. The aircraft failed to reappear and was located a short time later having crashed inverted adjacent to a road. The investigation revealed that, after liftoff from the strip, the aircraft had struck and severed power lines 82 metres beyond the end of the strip and eight metres above ground level. It continued to fly for a further 450-500 metres before striking the upper branches of 17-metre-high trees in a nose down attitude at a bank angle of approximately 90 degrees. Ground impact was 24 metres beyond the trees. The purpose of the flight was practice for a forthcoming commercial pilot's licence flight test for the pilot-under-instruction. His task was to locate and then conduct an airborne inspection of the strip and decide whether or not it was suitable for landing. The strip was regularly used for this purpose by the training organisation. It was assessed as a difficult strip because of its approaches and comparative short length. Pilots under training were, therefore, expected to decide against landing. A decision to attempt a landing would be countered by the instructor. The instructor (pilot-in-command) was familiar with the strip and was aware of the training organisation's policy that students were not to attempt to land on the strip. No fault was found with the aircraft, including the engine and flight controls, which might have contributed to the accident. The aircraft configuration at impact was landing gear up and flaps set at 20 degrees. (This is the flap setting listed in the Pilot's Operating Handbook for a balked landing.) The carburettor heat control was in the off position. Information from the Bureau of Meteorology indicated that the local wet and dry bulb temperatures at the time of the accident were 15 and 19 degrees Celsius, respectively. These figures indicate the probability of carburettor icing was moderate at cruise power and high at descent power. If icing was present, and the intention was to fly an approach to the strip and then conduct an overshoot, the performance of the engine could have been affected to the extent that a landing was unavoidable. Carburettor icing could also have affected the aircraft's climb performance after becoming airborne again from the strip. The evidence indicates that the wires had been cleanly severed by the propeller and had not contacted any other part of the aircraft. The effect of the collision with the wires on the aircraft's performance is difficult to quantify, but it is noteworthy that the aircraft flew for a further 450-500 metres after hitting the wires. It was not determined how far from the end of the strip the aircraft became airborne again. The angle from ground level at the end of the strip to the power line was 5 degrees. The Pilot's Operating Handbook indicates that in a maximum rate of climb configuration (full power, flaps up), the aircraft's climb angle is about 5 degrees. If the aircraft became airborne near the end of the strip, it might not have had the capability to climb above the level of the wires, particularly if the flap setting at this time was 20 degrees. Two kilometres beyond the end of the strip is a ridge line which rises 200 metres above the elevation of the strip. The accident site was in a valley which ran to the east of this ridge line, the position of the wreckage being some 200 metres left of the strip centreline but at substantially the same elevation as the strip. It is possible that the aircraft was deliberately flown along the valley to avoid the high ground and in an attempt to increase performance. The attitude of the aircraft when it struck the trees was indicative of the pilot having lost control.

Factors

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

1. Atmospheric conditions were conducive to the formation of carburettor ice.

2. For reasons which could not be established, the aircraft struck and severed power lines.

3. The pilot lost control of the aircraft.

Circumstances:

The pilot, accompanied by two employees, was carrying out an aerial inspection of a harvesting operation in a large open paddock. The aircraft had approached from the north, flying at approximately 150 feet above ground level, and carried out a right hand orbit. It then proceeded for a short distance in a southerly direction, before entering a steep descending turn to the left towards a three wire powerline positioned north-south across the paddock, the spans of which were approximately 30 feet above ground level. Approaching the powerline the aircraft was observed to climb rapidly, and a noise like a breaking stick was heard as the left hand wingtip contacted the centre wire of the powerline. The aircraft continued to climb steeply to about 80 feet above ground level. It faltered momentarily before stalling and impacting the ground 100 metres east of the powerline. The aircraft impacted on its left hand wing and nose. It bounced a further 25 metres while turning inverted and became engulfed in a ball of fire which reduced it to ashes. In 1988 the pilot received a serious head injury which resulted in the Civil Aviation Authority not renewing his pilot licence pending additional information from the pilot regarding his medical condition. The pilot did not provide sufficient information but continued to fly up to the time of the accident.

Significant Factors:

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

1. The pilot was conducting a low flying operation.

2. The pilot probably saw the powerline too late to avoid it.

3. The aircraft stalled at a height from which it was too low to effect a recovery.