While flying at approximately 150 feet agl on an instructional power line inspection, the instructor closed the throttle to simulate engine failure. The student turned towards a suitable paddock and commenced a practice forced landing. When it was assessed that the forced landing would have been successful the student was instructed to go-around. There was a minor delay in applying power during which time the aircraft continued to descend. The instructor then took control of the aircraft. The aircraft started to slowly gain altitude but due to the up sloping terrain and trees at the end of the paddock, the aircraft's rear fuselage collided with the trees. The instructor then closed the throttle and the aircraft settled into the trees. The student was a CPL holder and he had completed several low level forced landing practices. During these practices the student had always completed the go-around without difficulty. This fact influenced the instructor into allowing the practice forced landing to proceed to a lower level than would have been the case if the student had demonstrated some difficulty with the go-around. This expectancy that the student would perform the go-around without difficulty probably led to the instructor being slow to take over control of the aircraft in the very short time available to prevent the accident. The student was taken by surprise by the initiation of the practice engine failure. When a practice forced landing is started from 150 feet the whole exercise is compressed into a short time frame. This short time frame plus the additional work load from the practice emergency would have increased the workload on the student to a high level. The student believed that he heard the first command to go-around and started to increase the power, albeit slowly, but this is not supported by either the instructor or the passenger. The student was concentrating on successfully completing the forced landing practice and it is likely that a combination of channelised attention and high workload was responsible for the pilot not hearing the first command to go-around.

A descent from 3500 feet had just been commenced when the pilot heard a loud explosion. This was followed by a reported yaw to the right and the activation of several warning lights including the visual and aural engine fail warning. An autorotation was commenced and a Mayday call transmitted to Alice Springs Flight Service. The autorotational landing was accomplished between two sand dunes and on soft sand. During the landing the main rotor blades struck and severed the tail boom. The engine failure was initiated by failure of the first stage turbine wheel. The wheel fragmented when a fatigue crack in the wheel rim propagated to a depth of 4.85 mm (0.191 in.). There was no material deficiency or evidence of overheating in the blade root area. When the turbine wheel was fitted to the engine, cracks were noted in the wheel rim. It was estimated from a plot of fatigue striation spacings that these cracks were within acceptable limits as specified in Allison 250 DIL-190, which allows wheels with cracks in the rim less than 1.65 mm ( 0.065 in.). However, an inspection is specified after 500 hours or 500 cycles in service. Additionally, the manufacturer had calculated that the critical depth of this type of crack, beyond which failure may be imminent, was 15.4 mm (0.606 in.). The Operator's record keeping was deficient and the above inspection was not made before the wheel failed at 538 hours and 604 cycles. Had the turbine wheel been inspected at the appropriate time it is probable that the accident would have been avoided since the crack depth in the wheel rim must have been greater than that allowed in Allison 250 DIL-190. However, the turbine wheel failed after the fatigue crack had propagated only 4.85 mm which is well below the manufacturer's calculated critical depth of 15.4 mm. It is not known if the failure resulted from unusual circumstances or whether the calculated critical crack depth is in error. However, it is apparent that the critical crack depth for first stage turbine wheels should be re-assessed. The pilot executed an autorotational descent in accordance with the recommendations contained in the Bell 206 Flight Manual. The landing was normal for an autorotation but during the ground slide the pilot moved the cyclic control back as the helicopter approached some trees. The main rotor blades then severed the tail boom. The rearward movement of the cyclic control was a reflex type action rather than a deliberate control input.

The pilot was approaching the rear of a herd of cattle when he attempted to climb the aircraft. As he raised the collective control the engine RPM started to decrease. There was no suitable landing site below the helicopter so the pilot was forced to manoeuvre the aircraft around several trees to get to a suitable landing area. As he flared the aircraft for a landing the tail rotor contacted the ground and the main rotor severed the trunks of a tree and two saplings. The helicopter yawed to the left and slid sideways collapsing the left landing skid. The throttle control shaft output assembly, within the throttle control cambox had become dislodged, depriving the pilot of throttle control. The resultant freeplay within the throttle control system allowed the throttle butterfly to return to the idle position. The bearings and sleeves within the cambox are secured at manufacture by roll staking, which is considered to be the superior method for securing these components. However, the manufacturers maintenance instructions makes no mention of the method of securing the bearings and sleeves in the cambox. These components in the subject aircraft had been overhauled and were retained by the use of adhesive, which subsequently failed.

At about 500 feet above ground level after takeoff, just after the pilot commenced a left turn, the engine lost power. The pilot was unable to rectify the problem and chose a cleared area in which to land. During the approach it became obvious to the pilot that the aircraft would not make the selected area and he decided to land on a bush track. The aircraft touched down on the nosewheel and bounced, then touched down again before running through thick grass, coming to rest 74 metres beyond the second point of touchdown. A fire then broke out in the engine compartment, which subsequently destroyed the aircraft. The inspection of the wreckage was hampered by fire damage. However, a strip of the engine did not reveal any defects that may have contributed to the reported engine failure.

The pilot was manoeuvring the aircraft on the apron to park adjacent to another parked aircraft. Whilst making a right turn he was observing the other aircraft which was to his right, when the left wingtip struck a corner post of the airport boundary fence. The pilot had observed the fence post prior to commencing the turn and had assessed that there would be adequate clearance for the manoeuvre. However, he failed to continue monitoring the clearance with the post during the turn.

The pilot intended to position a beacon on the roof of the Perth Control Tower. The task was to be accomplished by sling loading the beacon, which weighed 199 kilograms, below the helicopter. The aircraft was positioned about 40 metres to the north and about 25 feet above the tower. The pilot carried out an approach to the roof and hurriedly deposited the load. The load was then released from the sling, which was left attached to the helicopter. The aircraft was then manoeuvred across the roof with the sling being dragged over the surface. The hook on the sling became snagged on the tower guard rail and halted the helicopter's progress away from the tower and causing it to pitch nose down and roll to the right. With the cable being tensioned by the pull of the helicopter the hook freed itself from the railing and the sudden relaxation of the load on the cable caused it to spring towards the helicopter. The cable flew up around the tail boom and became entangled in one of the main rotor blades. The other main rotor blade severed the tail boom which fell free of the helicopter striking the side of the tower on its way to the ground. The major section of the helicopter then fell to the ground at the base of the tower, caught fire and was burnt out. The tower roof was 90 metres above the ground and the baseplate, onto which the beacon was to be positioned, was triangular in shape with sides of about 60 centimetres long. Specialist opinion was that such a task would be difficult even under ideal conditions but there is evidence that a wind shear was present at about 300 feet at the time of the accident. The pilot's licence was not endorsed for sling loading operations and he was not sufficiently current on the aircraft type, considering its handling characteristics and suitability for sling operations, to undertake such a job. The ground crew were inadequately briefed about the job and their duties, and an inappropriate communication system between the ground crew and the pilot was used. The electric quick release for the lifting hook fitted to the helicopter was unserviceable although the alternate manual system was checked and found to be working. The pilot had recently been retrenched from his permanent employment and had not found other work. It is likely therefore, that he was excessively motivated to complete the task even though he was experiencing difficulty in accurately controlling the helicopter.

It was the student's fourth flying lesson and the effects of power were being revised. The student turned the aircraft 90 degrees to the left onto downwind but when he attempted to level the wings after the turn, the bank angle increased from about 30 to 50 degrees. The instructor took over the controls and attempted to recover by applying right aileron, full power and holding the nose up briefly. When the aircraft did not immediately recover, the instructor lowered the nose but the aircraft struck the ground, in a left wing, nose low attitude, before full control could be regained. After revising the effects of power, the engine speed was set too low for the aircraft to sustain a level turn. The student maintained altitude by progressively applying up elevator and the instructor did not notice the incorrect setting because speed was assessed with reference to the ground in a 20 knot tailwind. The instructor delayed taking over the controls, because he thought that the aircraft was being subjected to mechanical turbulence generated by trees, over which they had flown.

The aircraft was engaged in a demonstration of the dropping of emergency equipment from low altitude over the sea. This demonstration was being performed for the benefit of television news media personnel. The emergency equipment was contained in a bag which was connected to the aircraft by a static line. On the particular dropping run, the static line became entangled in the spreader bars of a sea anchor which had been packed in the bag. The entanglement prevented the bag from being opened, and it then swung below the aircraft before rising, passing above the horizontal stabiliser and striking the side of the fin and rudder. The static line was cut by the Assistant Dropmaster and the bag fell free. The aircraft remained under control and a safe landing was subsequently carried out. There had been no provision made to secure the anchor spreader bars to prevent their inadvertent deployment. As there had been no other recorded instances of the bars fouling the static line, it was probable that the bag had been incorrectly packed. This may have been related to distractions caused by the film crew during the packing sequence. There had also been no provision made to prevent the static line from blowing behind the bag during the deployment sequence. During the investigation, the pilot claimed that an underlying cause of the incident was harassment by Department of Aviation officers. This harassment included lack of advice and assistance in the development of the emergency dropping equipment, together with unnecessary restrictions being placed on the operation. Detailed interviews conducted with the crew of the aircraft established that all members of the team performed normally on the day. There were no major procedural variations introduced for the particular demonstration, and the operation had been performed successfully in the past. An assessment of the evidence obtained concluded that the alleged harassment was not a factor in the incident.

The pilot was flying the jump aircraft for a parachute club. After having completed the fifth drop for the day, the aircraft was observed to make a high speed pass, at an altitude of about ten feet above the ground, over a group of spectator parachutists. The aircraft then climbed steeply to an estimated altitude of between 200 and 300 feet before carrying out a wingover type manoeuvre. It then descended rapidly and impacted the ground in a slightly nose low, left wing low attitude, before nosing over and coming to rest 56 metres from the point of impact. The pilot was trapped inside the wreckage and the efforts of would be rescuers were thwarted by a fire which rapidly engulfed the aircraft. An examination of the wreckage failed to reveal any pre-existing mechanical fault. It was reported that the pilot had carried out similar manoeuvres on previous occasions, and had been counselled, about these activities, by the senior instructor at the parachute club.

The pilot was conducting cattle mustering operations. Weather conditions at the time were very hot, with a 10 to 15 knot wind. The pilot advised that while flying downwind at 30 knots and 80 feet above the ground, he commenced a pedal turn to the right. After some 90 degrees the turn suddenly stopped and the aircraft sank rapidly to about 35 feet above the ground. The main and tail rotors struck trees, but the pilot was able to maintain control and fly the helicopter to a clear area, where a safe landing was made. No defect was found with the helicopter or its systems which may have contributed to the occurrence and the reason for the loss of control, reported by the pilot, was not determined. This accident was not the subject of an on-site investigation.