Collision with terrain

After taking off on an aerial agriculture flight, the aircraft was observed to turn left at low altitude and dump the load. The left wing continued to drop and the aircraft collided with the ground.

The task was to spray a paddock which contained two sets of wires. The pilot was aware of the wires and planned to fly under the high-tension wires mounted on pylons, and over the smaller dual set of supply wires. On about the sixth spraying run, and after successfully flying under the high-tension wires, the aircraft was seen to level off in the pull-up manoeuvre and attempt to fly under the second set of wires. The aircraft contacted the wires and descended into the ground. It then bounced up in a fireball and impacted the ground a second time.

When observers arrived at the scene, the aircraft was burning fiercely, and rescue of the pilot was not possible.

The pilot was given a briefing and a map of the area to be sprayed. Both of these included information about the two sets of wires on the property. The pilot told the aircraft owner that he planned to fly under the first set of pylon wires and over the second set of smaller, lower wires. He was seen to orbit the paddock a number of times after arriving in the area and before commencing his first swath run. The pilot operated according to his stated plan for about six runs before he struck the wire.

The pilot was reported to have a safety orientated work ethos and demonstrated a professional approach to his work. His chief pilot had observed him on several occasions when he would have been unaware that he was being watched and, on these occasions, he did not demonstrate any unsafe tendencies.

Studies have been conducted over the years aimed at identifying deficiencies in agricultural operations, in particular, those associated with wire strikes. It is generally accepted within the aviation industry that wires present a constant hazard to agricultural flight operations, and, in this case, the pilot took appropriate actions to minimise the danger to his task. It was not determined why the pilot did not fly over the second set of wires, after successfully clearing them on about six previous occasions. The tolerances in an under and over operation, such as this, are narrow, and small distractions to the pilot's focus on the wires could result in a miscalculation.

No evidence of aircraft or engine malfunction was found in the investigation, nor was any predisposing medical condition identified. The pilot showed no signs of fatigue, and his demonstrated skills were suitable for the task allocated.

FACTUAL INFORMATION

History of the flight

The pilot had commenced mustering at about 0700 EST. At about 1030 the aircraft was refuelled to full tanks during a "smoko" break. The pilot's intention was then to muster about 30 head of cattle which had been separated from the main mob. The pilot had agreed to take a passenger on the flight which was expected to be of relatively short duration. The passenger had been holidaying at the property and was keen to experience a helicopter flight.  The helicopter became airborne at about 1050 and was last heard at 1115. At 1130 a jillaroo realised she could no longer hear the helicopter and began making enquiries on a hand-held radio. When nothing was heard, she began a search on a trail bike and eventually discovered the wreckage and the deceased occupants at about 1420.

Impact sequence

The tail rotor had struck the top branches of a lone 7-metre-high sapling, causing one blade to separate. The tail rotor gearbox then separated, and the main rotor struck the tail boom. The wreckage fell to the ground 30 metres beyond the sapling. The right side of the cabin was crushed. There was no fire.

Wreckage examination

The cabin was crushed on the right (pilot's) side by ground impact. The Perspex bubble was scattered in front of the main wreckage, which was facing south-south-west. The main rotor blades showed evidence of having struck the tail boom and the cabin structure. The tail rotor drive shaft was recovered and showed evidence of torque twisting, indicating that the tail rotor drive shaft was being driven under power when the tail rotor contacted the tree.

The left side of the passenger seat with the seat lap belt attachment, had detached from the fuselage structure and this allowed the passenger to strike the upper door frame during impact. The control systems were examined and appeared to be functioning normally. The engine governor switch in the end of the collective control was found in the off position.

The engine was removed and examined. There were no defects found which would have precluded normal operation.

Weight and balance

The weight and balance of the helicopter was within the limitations published in the aircraft flight manual.

Emergency locator transmitter (ELT)

The Ack Technologies ELT was found undamaged in the mounting bracket at the rear of the engine bay. The arming switch was found in the off position.

ANALYSIS

Civil Aviation Regulation Section 29.10 states that during aerial stock mustering operations, a pilot shall not carry more than one other person and that that person must be essential to the successful conduct of the operation. In this case, the passenger was not essential to the conduct of the operation. The helicopter had been refuelled to full tanks immediately before the flight and, although within the specified weight limitation, it was much heavier with the additional weight of the passenger than the pilot was accustomed to for mustering. Although the pilot was highly experienced, the resultant reduction in performance may have been a factor in his being unable to avoid the collision with the tree.

There were no witnesses to the accident and the final flight path before the collision with the tree could not be determined. However, it was evident that immediately after the tree was struck by the tail rotor, the helicopter was subjected to violent manoeuvres.

The RPM governor is fitted to the engine to prevent decay of rotor RPM when manoeuvring. The aircraft flight manual states that flight is prohibited with the governor switched off, except when there is a system malfunction or for emergency procedures training. The governor switch was found in the off position, but it may have been bumped to this position in the accident sequence. If it was deliberately switched off for the flight, manoeuvring performance of the helicopter may have been reduced.

The possibility that the pilot may have been attempting a precautionary landing for some reason such as an engine malfunction, was considered. There was no evidence found to substantiate such a possibility.

SIGNIFICANT FACTOR

The tail rotor struck a tree, and this precipitated a major structural failure. Why the pilot was unable to avoid the tree could not be determined.

At 2005 EST the pilot conducted an instrument letdown at Flinders Island and then notified air traffic services that he was proceeding night VFR procedures along the coast to Killiecrankie, a private airstrip approximately 15 NM to the north. He made an operations normal transmission at 2020 and advised he would call again by 2045. No further transmissions were received. An air and ground search was commenced.

FACTUAL INFORMATION

History of the flight

The pilot was conducting a charter flight from Roma to Quilpie, Windorah and Tanbar Station 100 km south-west of Windorah. The aircraft was refuelled at Windorah with 170.5 L of Avgas and departed Windorah at 1400 EST for Tanbar.  At 1739 the pilot transmitted flight-plan details to Brisbane Flight Service by radio for the flight to Roma. He advised that the flight would be conducted under the visual flight rules (VFR), and that the aircraft endurance was 250 minutes. He nominated a SARTIME of 2100 for his arrival at Roma.

At 1903 the pilot made an "all stations" broadcast 20 NM west of Charleville. He reported inbound on the 270 VOR radial on descent for a practice VOR approach and said that after a missed approach he would proceed to Roma.

Witnesses at the airport saw the aircraft fly overhead from the west. The aircraft was seen to turn right onto a southerly heading and soon afterwards the sound of the aircraft diminished. A bang was then heard and felt through the ground at about 1915. The aircraft wreckage was located the next day by a search party. The aircraft had struck the ground whilst banked vertically to the right with a 45-degree nose-down attitude, and disintegrated.

Pilot in command

The pilot was correctly licensed and endorsed to conduct the flight. Prior to the accident flight, the pilot had only 3.9 hours multi-engine command night experience. Although 6.5 hours single-engine dual night experience was recorded, no multi-engine dual night experience was recorded. The pilot had flown the aircraft in command at night on only three previous occasions. These were on 11 and 12 December 1995 (2.1 hours), and on 4 April 1996 (1.8 hours). The pilot held an instrument rating, but the flight was being conducted under night VFR.

Meteorological conditions

The meteorological aerodrome report (METAR) for Charleville on 16 April 1996 at 1900 hours reported the wind to be a southerly at 6 kts, visibility more than 10 km, and no cloud below 5,000 ft. Witnesses said it was a very dark night with no moonlight.

The VHF omnidirectional radio range (VOR) approach

The pilot broadcast his intention to carry out a practice VOR approach at Charleville when he was 20 NM to the west. The VOR approach is designed to allow an aircraft to descend on specified VOR radials to a specified minimum descent altitude (MDA) in instrument meteorological conditions (IMC). The Charleville runway 12 VOR approach MDA is 1,750 ft or a height above the aerodrome of 727 ft.

To commence the procedure when approaching Charleville from the west, a sector entry is carried out. This entails passing over the aid (VOR) at the initial approach altitude of 2,800 ft and turning right onto a heading of 146 degrees for 1 minute. The aircraft is then turned right to intercept the inbound leg of the holding pattern to overhead the aid. The position of the accident site suggests that this procedure had not been carried out, and that control of the aircraft was lost in the initial right turn from overhead.

Fuel quantity

The pilot refuelled at Windorah before proceeding to Tanbar. The main and auxiliary tanks were filled. No fuel was added to the tip tanks. The main tanks contained 204 L, and the auxiliary tanks 113.5 L, of useable fuel.

Engine instrument indications

During the on-site investigation the engine tachometers were recovered. The left engine tachometer was indicating 2,700 RPM, which is red-line or maximum RPM. The right engine tachometer was indicating 1,600 RPM, which is approximate flight-idle RPM. Both indicators were jammed in position by impact damage.

Fuel selector positions

The left and right fuel selectors and valves were recovered from the wreckage and specialist examination was carried out to determine the selector positions at impact.

The right fuel selector was found selected to MAIN. The selector pin was found secure in the handle although the selector knob was broken off. The pin was positively in the MAIN detent position. The right fuel-selector plate was minimally deformed with two of the three screws securing the plate to its base still in place. This means that the handle probably stayed in contact with the selector plate. That the pin remained, indicates that the selector was in MAIN for the whole impact sequence.

The left fuel-selector handle was found slightly anticlockwise from the MAIN position towards the AUX position. The left fuel-selector handle pin was deformed and depressed into the handle. The handle was thus free to move out of the detents. Examination of the left fuel selector showed deformation of the selector area, the handle subject to impact movement, multiple impact marks around the MAIN position, deformation of the selector plate around MAIN, a clear imprint of the handle above MAIN and an imprint in the plastic base of the selector in the MAIN position. The examination indicated that the left fuel selector was selected to MAIN at impact.

Exhaust pipe examination

Exhaust pipe sections from both engines were examined to assess the temperature at impact. Both exhaust pipe sections exhibited straw/gold coloured heat tinting. A temperature cannot be assigned accurately to a heat tinting colour, since the colour varies not only with temperature but with the time at that temperature. However, the presence of heat tinting does indicate that the exhaust pipes were hot (above 350 deg. C) at the time of impact, and that the engines were operating immediately prior to impact.

Aircraft and engines

Examination of the wreckage did not reveal any defects which may have contributed to the accident. There were no mechanical defects found on the engines which would have prevented the engines from developing normal power.

Emergency locator transmitter

The ACK Technologies emergency locator transmitter (ELT) (which complied with TSO C91a) was found outside the main wreckage unattached. The case was intact, and the three-position (ON-OFF-ARM) function switch was in the centre OFF position. The switch was not guarded and may have been moved in the impact sequence. The unit was functionally tested and found serviceable.

ANALYSIS

At the time of the accident, there was no moon, and the aerodrome pilot activated lighting (PAL) had not been turned on. After passing over the township, which is to the north of the aerodrome, the pilot would have had no visual horizon. The pilot's multi-engine experience at night was 3.9 hours, all of which was in command.

The flight times since the last refuelling at Windorah to arrival overhead at Charleville corresponded to that required to exhaust auxiliary fuel tanks. The pilot was known to have allowed auxiliary tanks to run dry before selecting mains on previous occasions. The fuel supply to the right engine may have been interrupted due to exhaustion of the right auxiliary tank. The operating handbook cautions against using auxiliary tanks in other than level flight due to the possibility of uncovering the tank outlet. Should this occur the engine is likely to lose power, surge and stop. Once the fuel system has ingested air, the engine cannot be restarted until the air is purged and a normal fuel flow restored. The fuel selectors appear to have been selected to the main tanks at impact, but as indicated by the engine tachometer readings, the right engine was not delivering power. This was most likely due to the right engine fuel system having ingested air before the main tank was selected.

The possibility of the pilot carrying out a deliberate asymmetric approach was considered. However, this would seem unlikely due to the demanding nature of the exercise and the pilot's low experience on type at night.

An unexpected power loss while the pilot's attention is concentrated on the flight instruments could be most distracting, even for an experienced pilot. The effect would be for his attention to be immediately diverted to the engine instruments, and then possibly the fuel panel. Cross reference between the attitude and performance instruments is required to perform instrument flight, particularly when there is no visual horizon. This is critical in multi-engine aircraft if an engine fails and asymmetric flight is encountered. Should cross-reference be lost for any reason and the aircraft allowed to get into unbalanced, uncoordinated flight, the aircraft may assume an unusual attitude. The pilot may then become completely disorientated and lose control of the aircraft.

The aircraft attitude at impact suggests that this occurred.

SIGNIFICANT FACTORS

1. The pilot was inexperienced on multi-engine aircraft at night and had not undergone night flying training on the aircraft type.
2. The aircraft carried sufficient fuel for the flight, and it is likely that auxiliary tank fuel was depleted or nearly depleted when the aircraft arrived overhead Charleville.
3. The weather was fine, but with no moon and no visible horizon, was unsuitable for VFR operations at night.
4. The pilot was conducting a practice VOR approach at Charleville.
5. The right engine was not developing power, most probably due to fuel starvation.
6. The pilot lost control of the aircraft for undetermined reasons during a practice instrument approach and the aircraft impacted the ground.

The aircraft crashed into the back yard of a property in Munro Street. Initial information indicates the aircraft was about to land at St George after a flight from Toowoomba. The aircraft operator advises that the aircraft was privately hired for a return flight to St George.

The aircraft departed Wee Waa at about 1755 EST with a load of 1450 litres of Endosulphan and Delphin spray mixture, to spray a cotton property 5 km east of Walgett. At about 1900 the aircraft was noticed by a witness in the adjoining property making a spray run from the north towards south. At the end of the run the aircraft pulled up and commenced a turn initially to the right then reversed the turn to the left. The left turn continued and the aircraft flew into the ground. The aircraft appeared to be operating normally up until the accident.

This accident was not subject to on-site investigation.

FACTUAL INFORMATION

Sequence of events

The occupants of the Piper Lance aircraft had planned an overnight stop at a farmhouse near the proposed landing area. The pilot in command spoke to his contact (another pilot) at Boddington by telephone at least three times on matters related to the landing area. Landing area details were discussed in depth and the contact indicated that the pilot in command should land towards the east in the paddock he recommended. It was also recommended that he complete a right circuit at 1,800 ft above mean sea level (1,000 ft above ground level) to remain clear of the surrounding terrain. Immediately prior to departure the pilot in command was told that the wind at the landing area was a north-westerly at 15 kts. During one conversation the pilot in command indicated that he would land at Narrogin if the landing area at Boddington was unacceptable.

The aircraft circled Boddington for 15 minutes before it made an apparent approach to land. During this time, it made a low pass alongside the proposed landing area.

The pilot in command did not follow instructions. He completed a left circuit at 500 ft above ground level and approached from the north-west at 45 degrees to the proposed landing direction. The aircraft descended to within 3 m of the ground, with landing gear and full flap extended. Power was then applied and a go-around commenced. The aircraft turned slightly left, passed between trees and continued to climb over rising ground. It was observed to veer towards the right during the climb.

Evidence indicates that the landing gear and flap remained extended during the climb.  The aircraft collided with a tree 900 m from the go-around point. The collision occurred 25 m above the ground and 3 m below the top of the tree. The aircraft was extensively damaged by the collision. It then crashed in a dam 50 m beyond the tree and to the right of the original flight path.

Damage to the aircraft

Damage to the aircraft indicated that its flying characteristics were adversely affected by the tree collision. Tree impact had severely damaged both wings and destroyed the control system located in the aircraft's lower fuselage. The pilot in command could not have exercised any control after that point.

Weight and balance

The aircraft's weight at the time of the accident was estimated at 1450 kg. Maximum weight was 1633 kg.

Personnel information

Despite the pilot in command's considerable flying experience, information provided by his associates indicates that he had always flown into and out of landing areas that were marked as flight strips. As a result, the pilot in command had not previously been confronted with the complexities of assessing whether a farm paddock met terrain clearance and aircraft performance requirements.

Post-mortem examinations did not disclose any medical condition that might have contributed to the accident.

Meteorological information

The weather conditions were recorded as fine, temperature 28 degrees Celsius with a wind from the north-west at approximately 8 kts.

Proposed landing area information

The paddock chosen for the landing was aligned east-west across a valley and included a grassed area 1,200 m long and 100 m wide. There were no other suitable paddocks in the immediate area. The grassed area was clear of obstructions but was not marked out as a landing strip. The proposed landing area sloped up from a river, towards the east and was contained within the grassed area. The slope was two degrees (3.4%) for the first 900 m, increasing to four degrees (6.8%) at the eastern end. There were ridges, 35-45 m higher than the surrounding terrain, at each end of the landing area. A displaced threshold, to assist the pilot in command during his approach over the high ground and trees, was marked by a car parked 300 m in from the western edge of the paddock. The car was also parked facing into wind, as arranged with the pilot in command, to indicate the wind direction. It was expected by the ground party that the pilot in command would make an approach for a landing towards the east (uphill). This direction meant the aircraft would land downwind.

A post-accident inspection of the paddock and an assessment using the approved landing weight chart indicates the proposed landing area did not meet the specifications contained in Civil Aviation Advisory Publication No. 92-1(1), Guidelines for Aeroplane Landing Areas. The average longitudinal slope was 5%. This exceeded the maximum of 2%. The landing distance available, after object clearance requirements were considered, was 530 m. This was 190 m less that the minimum distance calculated from the landing weight chart for the prevailing conditions. The pilot in command did not attempt to use the proposed landing area although it had been recommended to him by another pilot.

The approach direction used by the pilot in command was along the valley rather than across it. This allowed the pilot in command to fly a shallower approach than would have been the case had he used the direction recommended. It also provided a better climb-out route in the event of a go-around. However, fences and a dry watercourse reduced the actual landing distance available in this direction to 300 m, much less than the distance required.

Wreckage information

The wreckage was examined at the accident site and after removal to storage. The inspection of the airframe did not disclose any defects that may have contributed to the accident sequence.

Witnesses reported that the engine sounded normal during the climb-out after the go-around. Inspection of the engine indicated it was capable of normal operation and was developing power at the time of impact with the water.

An anomaly was found with the rear wing spar attachment points that might have affected the structural integrity of the aircraft. Post-accident inspection of the wreckage disclosed that the rear wing spar attachment points had been modified some time prior to the accident. The attachments had been cut to turn bolt holes into slots. The aircraft manufacturer has not approved this type of modification. There were indications that one attachment had been loose prior to the accident. No records were found relating to the modification. Discussion with one of the aircraft's owners indicated that the modification had not affected the aircraft's performance. It compared favourably with other PA32s also flown by the owner of the accident aircraft.

Aircraft performance

Performance calculations based on flight manual and manufacturer's information, indicate that the aircraft should have been capable of climbing clear of the terrain and trees following the go-around with the landing gear and flaps extended.

ANALYSIS

Proposed landing area

The recommendation by the ground contact and the acceptance by the pilot in command that the proposed landing site was suitable, indicates that neither had an adequate understanding of the parameters for an acceptable aeroplane landing area as set out in GAAP 92-1(1).

The pilot in command did not attempt to land in the paddock recommended by his ground contact at Boddington. This was probably because a later assessment from the air indicated that it was unsuitable.

The investigation could not determine why the pilot in command was not aware of the landing distance limitation on his actual approach path. It is possible that the obstructions did not become apparent until late in the approach as the fences and the dried watercourse would have blended into the surrounding dry grass. The attempted go-around probably indicates that the pilot in command realised the area was unsuitable during the latter part of the approach.

Go-around and climb performance

During the go-around the pilot in command did not retract either the flaps or the landing gear. The investigation could not determine the reason for this.

Performance calculations indicate that the aircraft should have been capable of climbing clear of the terrain and trees following the go-around. Why it did not could not be determined. Nor could it be determined why the pilot in command did not turn the aircraft further right, away from the trees and towards lower ground. The Piper Lance has an extended forward fuselage, restricting forward and downward visibility during a climb. It is possible that the pilot in command was not aware of the aircraft's proximity to the tree and that the collision was completely unexpected.

Wing spar attachment modification

It was not possible to determine when or why the holes in the wing rear spar attachments had been modified. It could not be determined what effect the modification and/or the loose wing spar attachment might have had on the structural integrity of the aircraft, particularly during the collision.

SIGNIFICANT FACTORS

1. A landing was planned and attempted in an area where there were no suitable landing sites.
2. The aircraft's climb performance was less than it should have been during the climb-out from the go-around.

SAFETY ACTION

As a result of the investigation into this occurrence, the Bureau of Air Safety Investigation advised the Civil Aviation Safety Authority of the details of the wing spar attachment modification.

FACTUAL INFORMATION

History of the flight

At approximately 0910 EST, the aircraft took off from runway 32 at Horn Island and commenced a normal climb. Shortly after, it adopted a nose-high attitude and commenced a wingover type manoeuvre to the right. Witnesses described the aircraft as being in a nose-low attitude, and at a height of approximately 600 ft to 700 ft above ground level after the completion of this manoeuvre. It then abruptly adopted a level attitude and rapidly entered a spin to the left.

Witnesses on the ground reported that at approximately the same time as the aircraft entered the spin, engine power became asymmetric, with the right engine continuing to deliver considerable power. The aircraft continued to descend in a fully developed flat spin, with no observed signs of an attempt to recover. The impact was heard shortly after the aircraft descended behind vegetation to the north-west of the aerodrome. The accident was reported to Flight Service by radio at 0918.

The wreckage was located on a beach approximately 2 km to the north-west of the aerodrome. The aircraft was destroyed by impact forces and the pilot sustained fatal injuries.

Wreckage examination

Examination of the wreckage indicated that the aircraft had impacted the ground in an almost flat attitude while rotating in an anticlockwise direction.

Examination of the airframe and flight control systems did not reveal any pre-impact malfunction or defect which may have contributed to the accident.

Damage to the right engine, and propeller blade slash marks on the trunks of trees at the accident site, indicated that the right engine was producing considerable power at impact. The left propeller was in the feathered position. The left engine and propeller were removed from the wreckage for further examination. There was no evidence of pre-existing defects. Subsequent tests determined that the engine was capable of producing power prior to impact.

Maintenance history

A review of the aircraft, engine and propeller logbooks found nothing to suggest any irregularity that was likely to have affected the normal operation of the aircraft during this flight.

Pilot information

The pilot was the holder of an Australian commercial pilot licence for aeroplanes.  He held a valid medical certificate, multi-engine command instrument rating and grade one instructor rating. At the time of the accident, he was the chief flying instructor for the company's flying school and carried out check-and-training duties for the company's charter operations. He had accumulated approximately 11,740 flying hours, of which 7,750 hours were acting as pilot in command of multi-engine aircraft.

The pilot was endorsed on the Aero Commander 500S on 15 October 1993 and had accumulated in excess of 119 hours on type. He had flown the accident aircraft on a number of occasions.

Results of the post-mortem and toxicological examination of the pilot did not indicate signs of incapacitation due to a medical condition or the presence of drugs or alcohol.

A review of the pilot's activities in the 72 hours prior to the accident established that he had been flying for another company in Cairns during the previous weekend. He had a late night on Sunday and was observed to consume a considerable amount of alcohol and smoke heavily on this occasion, activities which he reportedly had not engaged in for some time. He was described as in good spirits on Monday morning and departed for Horn Island during the afternoon. Monday evening was spent with other company employees at the local motel. During this period, he was not observed to consume alcohol. He returned to the company's accommodation on the island with one of the company pilots. They spent a short time talking before retiring at approximately 2200.

On the morning of the accident, the pilot was rostered to train one of the company pilots on the Aero Commander 500. After arriving at the airport by bus at approximately 0900 EST, he was observed to walk through the terminal and proceed directly to the aircraft. He was not wearing his uniform. Shortly after, the pilot was observed to start the engines of the aircraft and taxi to the runway holding point. Witnesses reported that they did not observe the pilot carry out a pre-flight inspection of the aircraft or any pre-take off engine checks.

Weather

At the time of the accident the wind was a light south-easterly and there was scattered cloud with a base of approximately 1,800 ft. The weather was not considered a factor in this occurrence.

ANALYSIS

The investigation established that the aircraft was capable of normal operation prior to impact. No evidence was found to indicate that the performance of the pilot was affected by any physiological condition which may have adversely influenced his ability to carry out his tasks.

As a result of discussions with a number of witnesses and friends of the pilot, it is apparent that his behaviour immediately prior to the accident was not in keeping with what most described as his thorough and professional attitude to aviation. Witnesses and friends also stated that they had never known the pilot to commence a flight when not wearing his uniform and without having carried out a pre-flight inspection of the aircraft or any pre-take-off engine checks.

The aircraft entered a flat spin at a height from which recovery may have been possible. The reason the aircraft entered the spin and subsequently crashed could not be determined.

CONCLUSIONS

Findings

1. The pilot held a valid pilot licence and medical certificate.
2. The pilot was endorsed on the aircraft type.
3. The aircraft entered a flat spin to the left with no reported signs of an attempt to recover.
4. The aircraft struck the ground whilst established in a flat left spin.
5. The right engine was producing considerable power prior to impact.
6. Indications were that the left engine was producing little or no power. Its propeller was in the feathered position prior to impact.
7. No evidence was found to indicate a malfunction or pre-existing defect with the aircraft or its systems which may have affected normal operation during this flight.
8. No evidence was found to indicate pilot incapacitation as the result of a medical condition or the presence of alcohol or drugs.
9. The pilot's behaviour on the morning of the accident was not consistent with what was generally accepted to be a thorough and professional attitude to aviation.

The crews of two helicopters had been engaged in survey work. On the morning of the accident, the second helicopter became unserviceable. The pilot and passenger, in conjunction with the pilot of the grounded helicopter, decided to continue on their own. About 45 minutes after commencing the flight, the helicopter flew up a dry creek line and struck a high-voltage single wire powerline. The line severed the flying controls at the mast. All control was then lost and the helicopter crashed into the dry creek bed.

When electrical power was lost at the cattle station homestead, search parties were sent in both directions along the powerline. The wreckage of the helicopter was found about 45 minutes after the power was lost.

The span of the SWER (single wire earth return) line struck by the helicopter was 490 m and was strung between two hilltops. The point of impact was approximately 40 m above the creek bed and about 20 m above the general tree canopy. This was the pilot's second day at the station. He was not familiar with the area south of the homestead which included the crash site.

Significant factors

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

1. The pilot was flying the helicopter at low level in a survey/mustering operation.
2. The second helicopter which had been used for lookout duties was unserviceable.
3. The pilot was unfamiliar with the area.
4. He did not see the SWER line in time to avoid a collision.
5. Control of the helicopter was lost when the wire cut control rods.