At the conclusion of a mustering operation, the pilot flew to a neighboring property. He made an approach to a line of the houses at the property but no-one came out to meet the helicopter. He then decided to hover-taxy to a shed some 90 metres away and land. Whilst taxying the helicopter at about 10 knots, the pilot suddenly noticed a three phase power line immediately in front of him, angled at about 30` to his track. He attempted to avoid a collision by initiating a back-up but the mainrotor mast and tailrotor became entangled in the three wires. The bubble was smashed by a flailing wire as the helicopter descended out of control. The ensuing landing was heavy, resulting in a collapsed left skid gear. The helicopter remained substantially upright. The pilot later said that the power poles supporting the span were obscured by trees.

Circumstances:

The pilot arrived at his destination and initiated a normal circuit prior to landing. After partially completing his downwind checks, and before he lowered the landing gear, the pilot decided to conduct a quick inspection of the property for flood damage. On returning for landing, the pilot did not make any further pre-landing checks and the aircraft touched down with the landing gear retracted. A pre-recovery inspection did not reveal any defects that would have prevented the landing gear extending had it been activated. The pilot reported that he had minimum flying currency.

Significant Factors:

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

1. The pilot had minimum flying currency.

2. The pilot interrupted his landing checks, and he did not re-start the checks when he joined the circuit the second time.

3. The pilot failed to extend the landing gear prior to landing. This accident was not the subject of an on-scene investigation.

The pilot had completed one circuit involving a touch and go landing and a go around from the second approach. Following the third approach the aircraft touched down then veered to the left as it commenced the landing roll. The pilot was able to arrest the left swing as the aircraft reached the left side of the runway but a swing to the right then developed and resulted in a ground loop. The left main landing gear collapsed and the left wing impacted the ground. The investigation revealed that the pilot had used an incorrect crosswind control technique and then failed to maintain directional control during the landing roll. There were no pre-existing defects with the aircraft which could have contributed to the accident.

Circumstances:

During the pre-landing checks the right main and nose gear gave normal green light "gear-down" indications. The left main gear green light remained extinguished, and the red gear warning light illuminated. The instructor took over control of the aircraft and proceeded to carry out the emergency procedures, including recycling of the landing gear selector. Selection of "gear-up" resulted in no change to the position indicators, and no audible indication of the landing gear moving up. When power was reduced, the audible warning for "gear not locked" was heard. The emergency extension procedure was then carried out but was also unsuccessful. A number of low passes were carried out under the observation of ground engineers who reported that the left gear appeared to be not fully down. Yawing and "g" manoeuvres failed to lock the gear down. During the subsequent landing roll the left main gear collapsed, the aircraft swung to the left and departed the runway. At this point, the right main gear also collapsed. The failure of the normal landing gear extension system was attributed to lack of hydraulic pressure but the reason for this was not determined. The failure of the emergency landing gear system was the result of a binding down lock assembly which did not allow the lock to fully engage. The landing gear balance spring was too weak to pull the left leg over centre. Subsequent receipt from the manufacturer of new springs of different tension is considered to have solved the problem. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. The main landing gear failed to extend due to lack of hydraulic pressure for reasons which were not established.

2. The Emergency landing gear lowering system failed due to weak balance spring tension.

Circumstances:

During a mustering flight, the spotter asked the pilot to drive some cattle towards the stock yards. The helicopter was flying slowly just above the tree canopy, when the spotter realised that something was wrong. Instead of turning to round up the cattle, the helicopter flew straight ahead, descending slowly. The pilot did not say anything, but the experienced spotter noticed that he was busy moving the pedals and cyclic control. When the main rotor sliced into the overhanging canopy of a large tree, the spotter jumped from the helicopter. The main rotor stopped when it struck the trunk of the tree. The helicopter then fell to the ground, coming to rest on its right side. The helicopter was being operated at or beyond its Out of Ground Effect (OGE) hover capability. The OGE capability was reduced by an operating weight in excess of the aircraft's maximum permitted weight and a loss of flight performance, caused by an internally mistimed magneto and, possibly, excessive control movements made by the pilot. Although the pilot had received some training in low flying, he had not received any training in the problems associated with operations in the mustering environment. The crash was probably survivable had the pilot's helmet remained on his head during the impact sequence. When the helmet was found, the chin strap was not fastened.

Significant Factors:

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

1. The pilot attempted an operation that was beyond his experience level.

2. One of the engine’s magnetos had an internal timing fault which was probably the result of inadequate maintenance procedures.

3. The helicopter was unable to maintain an expected OGE hover because; (a) the aircraft's weight was excessive, (b) the engine was not capable of producing its full rated power because of the faulty magneto and (c) the control inputs made by the pilot in an attempt to rectify the situation may have further degraded the power available.

4. The pilot was unable to avoid colliding with a tree.

Circumstances:

The pilot had not flown for about three weeks and was conducting his first Hang gliding flight from the site. The site was advanced rated, and the wind conditions were light and variable with occasional thermal gusts. The pilot was assisted in setting up the glider but declined launch assistance. He appeared anxious to begin the flight and was not seen to perform the mandatory hang check to confirm his attachment to the glider. Following a good launch the glider was observed to sink rapidly and fly in a straight path towards a large tree some 30 metres in front of the launch site. The glider struck the tree trunk, and the pilot was thrown clear. Examination of the equipment revealed no damage to the harness support system and no other pre-existing fault or damage. The flight path observed was typical of what would be expected if the pilot had failed to connect his harness to the glider.

Significant Factors:

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

1. The pilot apparently failed to perform a hang check before launch.

2. In not being attached to the glider the pilot was denied the normal means of control during flight.

3. The pilot was unable to avoid the obstruction.

The pilot reported that the helicopter was cruising normally at 2500 feet when there was a loud noise from the engine. He entered autorotation and landed but the helicopter rolled on its side on landing. Specialist examination of the engine revealed that the number four piston connecting rod failed as a result of fatigue cracking initiated by galling between the connecting rod and the crankshaft bearing. Galling is the deposition of metal from one surface on another when the two surfaces come into forceful contact. The galling was induced by continual over speeding of the engine. Other connecting rods from the engine also showed evidence of galling.

Significant Factors:

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

1. The engine had previously been subjected to over speeding.

2. The connecting rod suffered a fatigue failure as a result of galling.

3. Uncontained mechanical failure of the engine.

4. The pilot was forced to land the helicopter on unsuitable terrain. This accident was not the subject of an on-scene investigation.

A truck belonging to the pilot's company became bogged on the Normanton - Dunbar road. It was on its way to Rutland with materials needed at the property before the rain closed the road until the end of the Wet Season. A Carpenteria Shire grader was available to move the truck and two others also bogged. Unfortunately the grader had two flat tyres and no spares were available on site. Because of threatening rain the pilot offered to fly the grader driver to his camp to pick up some serviceable tubes. After locating the camp the pilot selected a stretch of road which after an aerial inspection appeared suitable for landing. Towards the end of the landing roll the aircraft veered left slightly under braking forces and the left wing tip struck a dead sapling not seen by the pilot during the aerial inspection.

Circumstances:

The aircraft departed on a flight to the Lake Eildon area. Subsequently, witnesses observed an aircraft, fitting the description of VH-GGS, operating at heights up to 200 feet above the ground/water level. The aircraft was later sighted near Woodfield flying at about 150-200 feet above the ground, tracking approximately north towards high ground, where it appeared to fly very close to the top of a hill. There were no witnesses to the remainder of the flight. Country Fire Authority personnel, investigating a reported sighting of smoke, discovered the burning wreckage of VH-GGS, surrounded by a grass fire. The aircraft had struck a single wire powerline, the impact severing the outer 1.3 metres of the right wing before the aircraft struck the ground 135 metres beyond the initial impact point. The wire was about 10 metres above the ground at the point of contact and strung between widely spaced poles that were difficult to see. Wreckage examination was limited by the extreme fire damage, but no evidence was found of any defects which might have contributed to the accident. The passenger knew a family at Lake Eildon. He had told them that he might fly over their property to let them know he was in the area.

Significant Factors:

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

1. The aircraft was intentionally operated at low altitude.

2. The pilot apparently did not see the powerline in time to take avoiding action.

Circumstances:

The flight was being conducted for the purpose of obtaining aerial photographs of a hospital located about two kilometres from the heliport. Two passengers were carried, one of whom was a photographer occupying the right seat. The weather was fine and mild, with scattered cloud at 2000 feet. The wind was reported to be south south-easterly at about 10-15 knots. The helicopter was seen to make a large right-hand circuit around the hospital at a height generally estimated to be between 600-1000 feet above the ground. It was then observed to commence a second circuit of the hospital. Whilst on a north-westerly heading, it was reported the aircraft either entered a hover, or slowed to a very low forward speed, for a short period. The nose of the helicopter was then observed to begin yawing to the right. The yaw developed into a series of tight spirals, during which the aircraft drifted in a downwind direction, at a relatively low rate of descent. Witnesses reported seeing the main rotor blades slow down during this phase. At about 50-100 feet above the ground, the helicopter was seen to then descend vertically in a steep, nose low attitude, substantially banked to the left, before impacting heavily in the front garden of an unoccupied house. Almost immediately after impact an intense fire broke out, incinerating the occupants of the helicopter before a rescue attempt could be made. The circumstances of the accident were consistent with a loss of tail rotor effectiveness, leading to an uncommanded yaw and loss of control. The aircraft was operating with a high-power setting at maximum all up weight, at a very low forward speed, out of ground effect. It is considered probable that the groundspeed of the aircraft was less than the tailwind component, resulting in a tendency for the aircraft to yaw to the right, into the relative wind. To counteract this tendency, the pilot would have required considerable left pedal to maintain a constant heading. If, as is considered probable, the aircraft yawed rapidly to the right, very little, if any, additional anti-yaw control would have been available from the pedals. In general, the most appropriate course of action available to the pilot, following an uncommanded yaw to the right, would have been to apply full left pedal to counteract the yaw and to apply forward cyclic control to increase airspeed and translational lift. A reduction of collective pitch could also have been used to assist in regaining directional control but may have resulted in an excessive rate of descent.

Significant Factors:

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

1. High gross weight combined with high required power.

2. Flight below translational speed, out of ground effect.

3. Tailwind component.

4. Uncommanded yaw due to loss of tail rotor effectiveness.

5. Following a loss of control, the pilot encountered conditions beyond his level of experience.