The Cessna 210 was engaged in flying tourists between Broome and Cape Leveque. The pilot had been with the company for one and half months and had flown eight hours in the Cessna 210. A substantial portion of his previous flying experience was in Cessna 172 and 182 aircraft. The pilot flew the aircraft to the Cape Leveque landing area at approximately 0930 WST. At around 1100, he loaded the aircraft and embarked his passengers; four adults and a five month old baby being held by his mother. The weather was fine with a light south easterly breeze. The pilot then attempted to start the engine but the starter would not energise. After consulting with the company's chief pilot, the pilot successfully started the engine.

The pilot completed his pre-take-off checks and began the take-off run. After approximately 200 metres, the pilot's side window opened. The pilot stated that the sudden noise surprised him and that he was concerned about dust entering the cabin and upsetting the passengers. He attempted to close the window whilst continuing the take-off run. The pilot stated that he managed to close the window but it immediately opened again. He recalled noticing in his peripheral vision that the aircraft was veering left. Evidence indicated that the aircraft veered approximately ten degrees left and continued in a straight path diverging from the runway centre.

The pilot returned his attention back to the take-off and believing the aircraft had sufficient airspeed, attempted to continue the take-off. He stated that just as he was pulling back on the control column to take off, the aircraft seemed to decelerate. Evidence indicated that the aircraft wheels struck freshly graded sand on the edge of the flight strip. Witness evidence and the wheel tracks in the sand indicated that the aircraft had pitched nose up and banked right with the right landing gear remaining in contact with the ground. With the throttle open, the aircraft continued for approximately 72 metres towards scrub adjacent to the runway.

The left wing struck a tree, slewing the aircraft left. The aircraft then continued sliding right before travelling forward into the scrub, impacting trees and stopping. The pilot and passengers evacuated through the right door. The aircraft's ELT operated correctly. It is probable that the pilot was distracted from controlling the take-off by the sudden and unexpected noise created by his window opening. There was sufficient available runway length for the pilot to discontinue the take-off and secure the window once stopped. The pilot could have also continued the take-off and attended to the window once safely airborne. He decided, however, to close the window while continuing the take-off. With his attention diverted in attempts to latch the window, he did not keep the aircraft tracking along centre of the runway. After the pilot realised that the aircraft had diverged left, he decided to continue the take-off without regaining the runway direction. The aircraft failed to become airborne, possibly slowed by the sand along the runway perimeter.

The pilot reported that after a normal approach in light wind to runway 14 at Coolangatta, followed by what appeared to be a normal touchdown, the nose gear collapsed. The aircraft came to rest nose down, supported by the propeller, 320 m from the runway threshold. The aircraft was undergoing first of type testing in accordance with CASA Flight Test Format for CAO 101.28 category aeroplanes. On the day of the accident the pilot had been conducting climb and stall tests at close to the maximum take-off weight (MTOW) at near the most forward centre of gravity. The maximum landing weight (MLW) is 1315 kg and the centre of gravity (CG) limits are between 1930 mm (forward) and 2132mm (aft) from the datum. At the time of landing, the approximate weight and balance was 1240 kg and 1948 mm. Examination of the runway revealed that the nosewheel had scored the surface for about 0.6 m at a point 87 m from the runway threshold (187 m from the runway end).

No further marks occurred until propeller strikes appear 133 m from the runway threshold, 187 m before the aircraft came to rest. Examination of the damaged nosewheel strut, which is a hollow metal tube, indicated that the fracture occurred at a point on the tube which may indicate defective welding or corrosion. Furthermore, where the strut was attached to the fuselage there was minimal movement or flexibility in the attachment to absorb shock or pressure. During static weight and balance measurements, the static weight on the nosewheel was 182 kg. Consequently, when the aircraft was landed at a heavy weight with a forward CG, excessive force may have been exerted on the nose gear the landing, causing it to fail.

The pilot has recommended that the structural integrity of the nosewheel strut be further investigated, redesign of the strut attachment, and a check of the elevator control system. He further recommended that the forward CG limit be reduced, and calibration of the airspeed indicator be carried out.

FACTUAL INFORMATION

The AS350 helicopter was engaged in a controlled burn of a logging coupe. A drip torch was slung underneath the helicopter. It dripped ignited napalm gel on command to initiate burning on the ground. The drip torch weighed 250 kg when fully loaded with napalm.

The pilot advised that while at 50 kts and 200 ft over cleared ground, the helicopter suffered a hydraulic failure. It banked violently to the right and the hydraulic warning light began to flash but the loud warning horn never activated. He turned the hydraulics off using the switch on the collective lever and regained level flight. The helicopter then banked to the right but not as severely. He tried to electrically release the drip torch from the cargo hook but it failed to detach. He then tried the mechanical release but the load still failed to detach. At the request of the pilot, the crewman on board also tried to mechanically release the drip-torch, but still the load would not release. For four minutes, the pilot flew the helicopter back to the airstrip under control, hydraulics off, with the hope of releasing the sling load and performing a run-on landing. He flew one circuit without being able to release the sling load. Then at about 40 kts and 200 ft AGL, the helicopter banked sharply left, pitched nose down, yawed left and entered a left spiral from which the pilot could not recover before ground contact. A crewman watching from the ground said that the helicopter banked smartly to the left and nosed down almost vertical to the ground with the drip torch swinging wildly underneath. Finally the helicopter landed on top of the drip torch. The main rotor and the tail rotor blades impacted the ground but the helicopter did not roll over.

After the accident it was discovered that the main rotors had struck the tail boom and the tail rotor drive shaft was severed. It has not been determined whether the drive shaft was severed in flight during an unusual manoeuvre or when the helicopter landed on top of the drip torch.

The load-ring attaching the drip torch cable to the cargo hook was oval in shape. The client provided the load-ring as part of the drip torch equipment. The ring had been manufactured to suit a slightly different type of cargo hook which may also be fitted to an AS350. Prior to being used operationally, inflight trials had been conducted with the load-ring to ensure it was not prone to dynamic roll out from the hook. The ring was in good condition and had been in service successfully for a considerable time. After the accident it was discovered that it was possible for the load ring to lodge itself partially around the cargo hook housing under negative "G" conditions. Once lodged around the housing, the rim of the only weld on the ring could snag on the housing. In this condition, neither the electrical nor the mechanical release system could detach the snagged load-ring.

The cable between the load-ring and the drip torch was not long enough to enable the pilot to land beside the drip torch with its cable still attached to the cargo hook. The existing cable length had proven to be successful during normal operations; its length minimised the potential pendulum effect of the load. If the helicopter pilot had been able to hover safely, hydraulics on, and rest the load on the ground, a crewman could have stood under the helicopter, de-snagged the load ring from the housing, and manually released the load.

With various combinations of helicopter cargo hooks and sling gear equipment, problems in not being able to release a slung load, or inadvertent load release, have been rare. Dimensions for the primary attachment ring to the cargo hook are contained in the AS350 flight manual supplement for the cargo hook. The load ring in use in this accident was larger than the dimensions described in the supplement.

Subsequent inspection of the hydraulic pump, its drive belt, the hydraulic servos, accumulators, and flight controls, found no significant fault with the mechanical aspects of the hydraulic system. No hydraulic fluid leaks were found. No fault was found with the hydraulic solenoid and switches. However several wires were found to be broken, mostly as a result of the damage sustained during the landing. The wire which controlled the hydraulic warning horn was found to be corroded and broken; this broken wire de-activated the warning horn. A wire to the hydraulic on/off solenoid was found to be broken but it could not be determined whether or not this wire was broken before the accident.

The company chief pilot had previously checked out the pilot and found him to be competent coping with hydraulic emergencies; this included successful hovering of the AS350 with hydraulics off. Weather was not a contributing factor in the accident. The helicopter was within its centre of gravity and weight limits.

ANALYSIS

The load ring was larger than allowed by the flight manual supplement. The way that the load-ring caught on the cargo hook housing was most unusual. Momentary negative "G" must have occurred in flight to have lifted the load ring high enough to snag.

Despite a thorough examination of relevant components no definite cause of the hydraulic failure has been ascertained. The problems encountered in flight by the pilot might have resulted from a wiring problem causing an uncommanded intermittent on/off situation with the hydraulics. The pilot may have experienced heavy, non servo assisted controls suddenly followed by servo assisted light control forces. This could partially account for the unusual inflight attitudes experienced by the pilot. The drip torch swinging wildly underneath the helicopter probably exacerbated the pilot's ability to control the helicopter.

SAFETY ACTION

The operator advised that load rings have since been replaced to prevent snagging. The operator has adopted a system of colour-coding load rings and cargo hooks to ensure that wrong size rings are not used on the variety of cargo hooks fitted to different helicopters owned by the company.

The provider of the drip torch has removed the oval load-rings from service and is working closely with the helicopter operator to ensure that sling equipment is compatible with the cargo hook fitted to helicopters used in controlled burning.

The student was approaching first solo standard, having completed some four hours of incident free circuits prior to a dual session of take-offs and landings. During the first take-off from runway 11C, just prior to rotation speed, the student applied full back stick and 'froze' on the controls. The instructor was unable to regain control before the Tomahawk lifted off and stalled at a height of about 30 ft. The aircraft struck the runway under full power, incurring substantial damage. Both the student and instructor were uninjured

After arrival in the circuit, when the landing gear was selected down, the pilot reported there was an unusual noise followed by a pronounced 'clunk', and the extension cycle stopped. The red gear unsafe light was illuminated and the gear motor circuit breaker had tripped. The checklist was reviewed and the pilot attempted to extend the gear using the emergency system. The emergency extension handle unlatched normally however, the handle was very difficult to move and jammed after about 30 degrees of its travel. The pilot eventually landed the aircraft on runway 29C with the landing gear partially extended.

A subsequent investigation revealed that the interconnect shaft between the forward main gear door motor and the rear main gear door lock mechanism had disconnected. This prevented the rear door locks from unlocking. The gear extension electric motor attempted to drive the gear down with the doors still locked closed, the motor stalled and the circuit breaker tripped. The heavy load on the rear doors prevented the pilot from releasing the door latches by the emergency extension system.

The interconnect shaft is normally retained by a bolt and split-pinned nut. These items were missing and were not recovered after the accident. The aircraft had undergone maintenance, which included an inspection of the landing gear, some 16 hours prior to the accident.

The pilot was carrying out spraying operations and had already spread two hopper loads of spray medium onto a cotton crop. Weather conditions were fine with clear skies and light winds from the north-north-east. The hopper was again filled, and two swathe runs were completed. The pilot reported that on the third swathe run, he left the pull-up manoeuvre to clear trees too late, and the aircraft's propeller collided with branches.

The aircraft initially gained about 100 ft following the collision, however, it then commenced to lose height. The pilot quickly realised that the impact had caused damage resulting in a loss of power and/or thrust. In an attempt to improve the aircraft's climb performance, he selected the dump valve to the fully open position and jettisoned the remaining hopper contents. This action failed to arrest the sink rate of the aircraft and it subsequently stalled into trees and collided with the ground. Whilst the pilot escaped with minor bruising, the aircraft was consumed by fire.

The pilot planned a flight from his base at Tooradin Vic, to Torquay Vic, accompanied by his son who also held a private pilot's licence.

The pilot advised that although he was familiar with the Torquay airfield layout he had not landed there before. Prior to leaving Tooradin he obtained airfield information from the Aircraft Owners and Pilots Association (AOPA) Airfield Directory and telephoned the operator for approval to land. He inquired about local conditions and was told that there were parachute operations at Torquay that day.

When he arrived in the Torquay area, the pilot listened out on the appropriate frequency and heard another pilot announce that that he was landing on runway 18. The pilot joined crosswind for a landing on runway 18, and while in the circuit observed the marked taxiway and worn take-off area at the threshold of runway 18.

On final approach to land, the aircraft collided with powerlines placed along the road adjacent to the threshold of runway 18. One powerline passed over the fuselage, damaging the horizontal and vertical tail surfaces. The other powerline broke the cockpit canopy and snagged on the roof structure. This powerline was pulled from the pole and stretched, allowing the aircraft to travel 70 metres before settling onto the ground in a level attitude. The pilots stayed in the aircraft until electrical power was disconnected. The aircraft was substantially damaged.

The "Special Procedures" section of the Torquay entry in the Airfield Directory did not mention the power line. AOPA advised that the details contained in the directory were supplied by the airport operator. The operator advised BASI that he had not brought the line to the attention of the pilot when he telephoned for permission to land.

There were two thresholds in use on runway 18 at Torquay, one for take-off and one for landing. Because of the powerlines, the airport operator had placed displaced landing threshold markers some 150 metres into the 805-metre strip in an endeavour to establish an approach gradient that would give adequate clearance over the powerlines. The markers were white and may not have established an effective contrast with the airfield surface under the prevailing dry conditions.

The take-off threshold was adjacent to the fence line with taxiway markers and runway edge markers delineating the take-off area.

The powerlines were made of steel which had a light-grey galvanised finish. The lines were fitted with 200-mm diameter orange marine buoys, the upper sections of which had bleached white. Power supply company records show that the orange marine buoys had been fitted some 8 years prior to the accident. The power supply company manuals did not contain standards for marker buoys, nor was there any requirement to check for ultraviolet degradation during the 3-yearly powerline inspection cycle.

The markers pre-dated the formulation of the Australian Standard for powerline marking.

The accident occurred in bright but overcast lighting conditions at the end of a hot dry summer so that the airfield surface was light brown in colour. The dry background, the oxidised wires, the degraded orange markers, and the displaced landing threshold markers were all of a similar colour to the airfield surface. Therefore, the powerlines would have been very hard to detect.

Because the pilot had not been warned of the existence of the powerlines he would have had a lowered expectation of their presence.

After the accident the pilot said that he considered the use of separate landing and take-off thresholds confusing, especially when the latter was neither adequately marked nor mentioned in the airfield directory.

Safety action

1. The operator is ensuring that all pilots who telephone for landing approval are thoroughly briefed on the existence of the powerline and the use of the displaced landing threshold.

2. The operator has enlarged the property and extended the runway. This has allowed the displaced threshold to be placed approximately 300 metres from the fence line and the powerline.

3. The operator has revised the entry in the AOPA airfield directory to include details of the powerline and the displaced threshold.

As a result of the investigation into this occurrence, the Bureau has made the following recommendations:

R970153: The Bureau of Air Safety Investigation recommends that the Electricity Supply Association of Australia make known to its members the circumstances of the accident and make appropriate use of the applicable Australian Standard (AS 3891.1) when marking powerlines.

R970177: The Bureau of Air Safety Investigation recommends that the Australian Airport Owners Association make known to its members the circumstances of the accident. The association should also recommend to its members that they contact their local electricity supplier if they believe any powerlines affecting their airfields are not marked in accordance with the Australian Standard.

R970178: Windsock Productions, publishers of The Country Airstrip Guides, gathers information regarding aerodrome and landing areas by asking operators to fill in a survey form and return it to them. The Bureau of Air Safety Investigation recommends that Windsock Productions amend that survey form to include, as examples, a detailed list of possible hazards, obstacles and special procedures an operator needs to consider when completing the form.

R970179: AOPA, which publishes the Airfield Directory, gathers information regarding aerodrome and landing areas by asking operators to fill in a survey form and return it to them. The Bureau of Air Safety Investigation recommends that AOPA amend that survey form to include, as examples, a detailed list of possible hazards, obstacles and special procedures an operator needs to consider when completing the form. The Bureau also recommends that AOPA inform its members of the circumstances of this accident.

Sequence of Events

The pilot was conducting aerial inspections of local roads affected by recent flooding. On board with the pilot were two council inspectors. The pilot reported that the helicopter struck a powerline as he was positioning for a closer look at a damaged section of roadway. The helicopter then impacted the ground coming to rest on the side of the road.

One passenger received minor injuries, the pilot and second passenger exited the helicopter without injury.

The helicopter was fitted with a Pointer 3000 Emergency Locator Transmitter which activated automatically.

The pilot reported that he had obtained a weather briefing from the Bureau of Meteorology at Cairns, prior to the flight. This information including early morning observations from Mareeba Airport. After selecting a launch site to the south-east of Mareeba, Winds in the area were again assessed using a weather balloon. The departure and flight were uneventful until north-east of Mareeba, when the pilot became aware that the surface wind was a southerly, gusting between 10 and 15 kts.

During the approach to land, at about 90 ft above ground level, the balloon was effected by a wind rotor near some trees. The rotor distorted the canopy and caused it to lose heat. As a result a high descent rate developed. The pilot estimated that about 50 ft of height was lost before he was able to arrest the descent using the burner. During the latter part of the descent, the basket and lower flying wires struck the branches of a tree, causing damage to lower panels of the canopy. A fast landing then ensued. After landing, the canopy was further damage when it became entangled in a barbed wire fence.

The pilot reported that a rain shower was experienced some minutes after the landing. He believed that the unusual localised wind during this accident was due to the approaching rain.

The pilot reported that during the take-off run the aircraft was not accelerating very well due to the soft wet surface.

At about 70 knots the pilot raised the nose in an attempt to get the main wheels off the runway to allow the aircraft to accelerate in ground effect. The pilot said that as soon as the aircraft lifted off it veered slightly left and was about to settle onto the ground again, so he closed the throttles and tried to maintain directional control on the ground. The aircraft entered mud and grass to the left of the runway for about 200 metres. The nosewheel then broke off, the propellers struck the ground, and the aircraft came to rest in about 8 metres.

The passenger who was an engineer, had previously run the left engine as it was suspected to not be producing full power. No fault was found with the engine. During the accident take-off the engineer had noted that the left engine was performing normally.