The pilot reported that while mustering cattle he was attempting to turn an animal that had broken away from the mob. During this procedure the pilot attempted to climb the helicopter over a line of trees, however, the main rotor blades struck the top of one of the trees. The helicopter was landed and an inspection found that the main rotor blades required replacement.

Circumstances:

The pilot had hired the helicopter to fly a friend to his property situated about 2500 feet above sea level. On arrival the pilot landed next to the homestead and removed the passenger door so that his friend could take aerial photographs. The weather was fine, with a 10-knot wind from the north-west, and a temperature of 30 degrees Celsius. The density altitude was 5500 feet. After flying the helicopter around the property boundary, the pilot considered that it may be more advantageous if they climbed higher from where a more panoramic view of the property could be obtained. A climb was made in an easterly direction, at a slow forward speed, to about 500 feet above ground level, at which point the helicopter began to pitch and fishtail from side to side before descending rapidly. This was witnessed by a farmer working nearby, who said that he did not hear any change to the normal sound of the helicopter before it disappeared behind a ridge. The helicopter contacted the tops of the trees at a very slow forward speed and low main rotor RPM. During its descent through the trees to the steeply sloped forest floor the helicopter struck, and broke off, a large branch which entered the cabin resulting in a fatal injury to the pilot. The helicopter came to rest on its side, 19 metres from the initial contact point with the trees. The pilot had only recently qualified for his Private Pilot Licence (Helicopter) and had not received instruction in the methods for conducting helicopter survey or photography operations. There was no evidence that the helicopter was not capable of normal operations prior to the accident. Investigation found that the helicopter, which had been relatively heavy but within limitations, was operating at a high-density altitude and a slow forward speed while climbing in a downwind direction. The subsequent loss of translational lift and true airspeed (TAS), combined with a reduction in engine performance due to the conditions, required the pilot to use considerably more power and collective pitch than normal to commence and maintain the climb. When the helicopter's operation became erratic, the pilot told the passenger they would fly out of the situation and mentioned autorotation. He was observed by the passenger to be making rapid movements of the controls with his hands and feet. The circumstances of the accident were consistent with the pilot probably allowing the main rotor speed to decay due to overpitching of the rotor system, then using large left pedal inputs to prevent the helicopter from turning. The increase of tail rotor pitch further assisted decay of the main rotor speed. The low inertia rotor system used on this type of helicopter makes it susceptible to rapid rotor speed decay, but it can be regained quickly if there is no delay in effecting recovery action. The speed and height of the helicopter placed it in the avoid area of the height-velocity curve, and the action by the pilot of entering an autorotation failed to restore the main rotor RPM. If the helicopter had been allowed to weathercock into wind, then flown away towards the lower cleared terrain, a successful recovery may have been accomplished. As the helicopter descended rapidly towards the trees, the natural reaction of the pilot would have been to pull up on the collective pitch lever in order to arrest the descent, causing a further reduction to the remaining main rotor speed. This was evident by the lack of rotational damage to the main and tail rotor blades, however this action probably reduced the helicopter's vertical descent speed sufficiently to prevent more serious injuries to the passenger. When the rotor speed decreases below 95 percent a warning horn sounds and an amber light illuminates. During the descent, the passenger could not remember hearing a horn blowing but had seen lights flashing on the instrument panel. When the problem commenced, he may not have registered any noises but did notice the warning light. There are several warning lights in the Robinson R22 helicopter, and each associated system was checked and found serviceable. The type of operation, and prevailing weather conditions, would have required the manufacturer's performance criteria to be observed, and a considerable amount of attention given to flying the helicopter.

Significant Factors:

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

1. The helicopter's performance was affected by the hot weather and high-density altitude conditions.

2. The pilot had not received training to perform aerial photography.

3. The pilot climbed the helicopter downwind at a low forward speed.

4. The pilot did not adequately compensate for the prevailing weather conditions, probably due to diverting his attention to photographic considerations.

5. The pilot overpitched the rotor system and then did not effect a successful recovery of the main rotor speed.

Circumstances:

The student helicopter pilot was at an early stage of his training, however, he was a very experienced fixed-wing pilot. Before conducting some circuits, he was given practice in hovering. After this the instructor took over to demonstrate the manoeuvrability of the helicopter with the rotor disc steady. During this hovering the height increased to about 30 feet before the aircraft began to spin rapidly in an anticlockwise direction and dive towards the ground. The low rotor rpm warnings sounded during the descent. Impact evidence showed that the helicopter had struck the ground at a high rate of descent while travelling forward slowly. No signs of engine malfunction were found.

Significant Factors:

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

1. The instructor did not maintain directional control of the aircraft.

2. The instructor did not maintain adequate rotor rpm.

3. The instructor was operating outside the safe flight envelope.

The pilot was engaged on a survey flight for the owner of Coolibah Station, the operator of the helicopter. While flying at approximately 500 feet above ground level(agl) a turn downwind was initiated. The helicopter was close to maximum all up weight and it started to lose altitude. The pilot started to apply more power but the helicopter continued to sink and the rotor rpm decayed. The pilot saw a gap in the trees and attempted to land in it, however, the mainrotor hit a tree. The helicopter then slid along on the skids for approximately 10 metres before they dug into the ground and the helicopter nosed over. The pilot was engaged in conversation with the passenger and allowed himself to become distracted. He may have commenced recovery action too late. However, the helicopter was descending downwind which are conditions which predispose towards settling-with-power. Settling-with-power happens when the mainrotor is settling in its own downwash and additional power will not stop the descent. The pilot's statement that he was applying more and more power but that the helicopter kept sinking indicates that settling-with-power was likely. Part of the technique for recovery from settling-with-power is to increase indicated airspeed before increasing power. This accident was not the subject of a formal on scene investigation.

Circumstances:

On the day before the accident, the pilot had been mustering cattle on Cukadoo Station which is the neighbouring property to Nithsdale. The owner of Cukadoo had accompanied the pilot during the mustering operation, which was close to the accident site. The pilot had flown over a single-wire powerline several times during the day and remarked that he would have to be careful of the powerlines. This was a spur line which joined the main line (which the helicopter struck) at right angles, approximately 1.4 km from the accident site. Late in the afternoon the pilot flew to Mt Isa, where he remained overnight, with the intention of returning to his own property in the Northern Territory the next day. During the evening, he had telephoned the owner of Mt Ryde Station west of Longreach, where he had cattle on agistment. The cattle were being driven to another property in the Northern Territory recently purchased by the pilot. The pilot was told that some of the cattle were still at Mt Ryde, and he became very concerned. The pilot said he would come down to Mt Ryde to resolve the matter. At about 0930 the next morning the sound of a helicopter was heard passing near Cukadoo homestead 200 km southeast of Mt Isa at very low altitude. Initially it appeared that the helicopter was going to land there, but the noise receded towards the southeast without the helicopter being sighted. About 5 minutes later the electricity supply to the homestead failed. Later in the day the wreckage of the helicopter was discovered by linesmen who were investigating the cause of the electrical supply failure. The helicopter had struck the Single Wire Earth Return (SWER) 19 Kilovolt line 9.5 km southeast of Cukadoo homestead. The wire was struck approximately mid-span between supporting poles 400 m apart, and about 7.5 m above ground level. The line was aligned approximately at right angles to the south-easterly flight path of the helicopter. The wire impacted the nose of the helicopter at about floor level, causing the helicopter to pitch nose-down, and the main rotor to sever the tail boom. The helicopter then impacted the ground and burned. Wreckage distribution indicated that the helicopter may have been at cruising speed at the time of impact with the wire. The location of the accident was approximately on track between Mt Isa and Mt Ryde. The powerline was in flat open grassland which could cause the poles to blend with the background. At the time of the accident the weather was fine, but there was a 10 to 15 knot south-easterly wind, and it appears that the pilot may have been flying at low level in an attempt to conserve fuel. There were no mechanical defects discovered which may have led to the development of the accident.

Significant Factors:

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

1. The helicopter was being flown at an extremely low height.

2. The pilot failed to see or avoid the powerline.

The aircraft was being used for dual instruction when the attention of witnesses standing on the beach was drawn to it by a loud report. The aircraft was observed to be falling almost vertically, with both wings trailing, from an altitude of about 150 feet. It impacted in the sea about 100 metres from the shore and disappeared. Inspection of the wreckage found that the design of the control system was such that with certain control inputs the rear control cables could foul the propeller. On this occasion the left rear control cable had been severed by the propeller and this had resulted in the total collapse of the wing.

Circumstances:

The pilot was flying his first period of solo practice forced landings. Circuits were flown at 1000 feet above ground level (agl), and the landings were terminated using the introduction of power from about 100 agl, without making a touchdown. On the fifth circuit, the pilot noticed an engine vibration commence at about 500 feet agl and worsen as the approach was continued. At about 60 feet agl, the pilot attempted to introduce power but obtained no response from the engine. Further attempts to obtain engine power were made, without success, as the pilot continued with the forced landing. The touchdown occurred with little rate of descent or forward speed; however, the aircraft was moving sideways slightly and rolled on its side. Other pilots had previously reported intermittent rough engine running. The reason for the rough running on this occasion was undetermined; however, the engine was close to the end of its overhaul life. The piston rings and valves were in poor condition but operating within limits.

Significant Factors:

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

1. The engine lost power for undetermined reason.

2. The pilot did not have the helicopter aligned with the direction of travel at touchdown

Circumstances:

The helicopter was to be used to move cattle from one paddock to another on the property. Staff expected that the aircraft would return to the refuelling point around 1100 hours local time. A search was commenced at about this time. The wreckage was located in the mustering paddock at about 1230 hours. Examination of the wreckage indicated that the tail boom had been moved in an anticlockwise direction into the top of an 11-metre-high gum tree. The tail rotor blades struck the tree trunk, which was 25 millimetres in diameter, and part of one blade broke off. Out-of-balance and still rotating the entire tail rotor and stabilizing fins separated from the tail boom. The main body of the helicopter then struck the ground at a very high rate of descent. There was no horizontal speed, yawing or bank at the time of impact. The pilot was unable to remember the accident circumstances and there were no other witnesses.

Significant Factors:

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

1. The area contained occasional trees significantly higher than the surrounding bush.

2. The tail rotor struck the top of a tree for reason/s that could not be determined.

The aircraft had been engaged in spraying a carrot crop. The pilot reported that as the aircraft descended for a spray run, the engine failed completely. The pilot made a forced landing in the crop. The gear was torn off and the aircraft came to rest 30 metres from initial touchdown. The pilot reported that the engine failure had been caused by fuel exhaustion. He reported that he had been distracted at his last stop. The hopper had been loaded but he had failed to refuel the aircraft. This accident was not the subject of an on-site investigation.

The pilot had commenced superspreading operations at about midday, and was returning to his base strip at the completion of the day's activities. He was landing towards the west. The strip slopes up 4` to the west. The pilot reported that he had not been aware until the flare that he was landing with a tailwind component, as there had been a westerly component in his operations area. He touched down some distance along the strip. Due to looking into the setting sun, he misjudged the distance remaining and was slow to apply braking. When it was obvious that the aircraft would not stop before the boundary fence, he turned the aircraft to the left to minimise damage. The outer right wing struck a fence post.