Collision with terrain

Whilst being hover taxied between hangars, in strong gusty wind conditions, the helicopter rotated rapidly to the right, struck the ground, and rolled onto its side. Both occupants were able to evacuate the machine without injury. The instructor pilot reported that the helicopter was being flown by the student pilot at the time.

With the wind gusting from the south, the aircraft was lifted into the hover on an easterly heading, then rotated to the right through 180 degrees. As it approached a westerly heading it swung rapidly to the right. Full left pedal and power reduction failed to arrest the rotation which continued for two or three turns before the helicopter struck the ground and rolled onto its side.

No mechanical defects were reported that may have contributed to the accident. It was the opinion of both the instructor pilot, and the operator's chief pilot, that the accident was consistent with the loss of tail rotor authority.

The helicopters main rotor blades came into contact with a tree during a low-level fence inspection operation. The helicopter then descended out of control into a flooded river and submerged. The pilot and observer egressed safely from under the water.

The pilot reported that he had manoeuvred the aircraft to within about 10 metres of some tall trees beside the river, in order to give the observer the best possible view of a section of fence. At this point the helicopter yawed left and the main rotor blades struck a tree. Later the pilot said that he though the tail rotor blades may also have struck a tree. After the tree strike the pilot had insufficient control and was unable to prevent the aircraft descending sideways into the river.

The wreckage was not recovered from the river for several weeks, due to flooding and continuing torrential rain. Later examination of the wreckage did not reveal any pre-existing mechanical fault which may have contributed to the accident. The tail rotor assembly was found to be intact and attached to the boom. No evidence was found to indicate the tail rotor blades came into contact with the tree.

The pilot took off to conduct a low-level aerobatic display. Shortly after liftoff, at a very low height, he rolled the aircraft inverted. He applied forward elevator to hold the nose up to avoid a descent.

At that point a blanking nut came off the top of the canopy and the pilot instinctively reached for it. As he did so, he inadvertently allowed the aircraft to descend inverted onto the runway surface. While still inverted the aircraft slid to a stop on the runway.

Significant Factors

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

1. The presence of the loose blanking nut.

2. Low height of the aircraft.

3. The pilot allowed himself to be distracted from his primary task of flying the aircraft, at a crucial stage of the flight.

The pilot planned a scenic flight from Cambridge Airport, Hobart to Bathurst Harbour and return, with an intermediate stop at Melaleuca airstrip adjacent to Bathurst Harbour. The airstrip is situated in low scrub country surrounded by mountains, is 450 metres long and has a white gravel surface.

The pilot commenced flying in 1977, had flown a total of approximately 390 hours, 20 hours of which were in the past year.  Most of his recent flying had been on Cessna 182 aircraft.

On arrival at Cambridge the pilot found that the Cessna 182 aircraft had been refuelled to full tanks. He was concerned about operating into Melaleuca with four persons and full fuel. While the operator's chief flying instructor was under no obligation to provide the pilot with any advice or assistance, he advised the pilot to fly around for a while to burn off fuel prior to landing. Neither the pilot nor the chief flying instructor used the landing and take-off charts supplied by the operator to calculate the take-off and landing performance, or the weight and balance of the aircraft for the flight. Calculations have shown that the aircraft departed Cambridge approximately 14 kg above its maximum permitted take-off weight.

The flight proceeded along the coast towards Bathurst Harbour.  The weather was fine with a light and variable breeze.  On arrival in the Bathurst Harbour area the pilot overflew Melaleuca airstrip and continued on to Port Davey, a further 17 km to the north west. He then turned the aircraft to the south east and commenced a long, straight-in approach to the airstrip.  Straight-in approaches are not approved for operations into airstrips such as Melaleuca. The statutory requirement is that all aircraft must join the circuit on the upwind, crosswind or downwind leg.

Two persons, one a commercial pilot, observed the approach from a boat moored 100 metres from the threshold of the strip. The aircraft was seen to be very low and continued to descend until it impacted an embankment one metre below the strip surface. The aircraft overturned coming to rest 14 metres into the strip. The persons from the boat ran to the inverted aircraft, initiated rescue action and extinguished a fire in the engine bay.

The passenger sitting in the seat to the right of the pilot recorded much of the flight on a video camera. The video showed that the pilot conducted the final part of the straight in approach at extremely low height and at very slow speed. Full flap was extended, and the stall warning horn was sounding continuously for the last six seconds of the recording. The recording showed that just prior to impact the right wing dropped sharply, this being confirmed by ground impact marks. In the last second of the recording an increase in engine power could be heard.

The wreckage was examined, and no defects were found that could have contributed to the accident.

Analysis

By carrying out a straight-in approach the pilot did not comply with the statutory requirements for circuit entry. In doing so, he also denied himself the basic visual cues, associated with flying at least three legs of a circuit, which assist in establishing a safe approach to land. Melaleuca is a short strip and as such needs an accurate and disciplined approach to land in this type of aircraft.

The advice given by the chief flying instructor was inadequate. Had he required that the pilot utilise the operator's performance data, they would have found that the aircraft was above its maximum permitted take-off weight for departure from Cambridge, and that the landing distance available at Melaleuca was inadequate for the aircraft given the loading and weather conditions existing at the time.

Conclusions

Findings

1. The aircraft was serviceable and carried sufficient fuel for the intended flight.
2. The pilot had low total and recent experience
3. The pilot made inadequate preparations for the flight.
4. The chief flying instructor gave inadequate advice to the pilot.
5. The aircraft departed Cambridge in excess of its maximum permitted take-off weight.
6. The landing distance available at Melaleuca was inadequate for the aircraft in terms of its landing weight and the weather conditions existing at the time.
7. The pilot did not conform to the statutory requirements for circuit entry.

Factors

The following significant factor is considered relevant to the development of the accident:

1. The pilot did not recognise and correct an approach to land that was too low and too slow.

The pilot reported that he approached the landing site at about 500 ft AGL in light drizzle. There were thunderstorms in the area and the wind was gusty and changing direction.

An approach was made to runway 27 at 500 ft. On final, 10 degrees of flap was set and the aircraft descended to 250 ft. The pilot then decided that he was too high to land, and a go-around was initiated. The aircraft turned onto cross wind at 80 kts. As the aircraft turned down wind, the pilot looked back at the runway. When he looked forward again, he realised the aircraft was very low to the ground. He applied full power and full back stick, but the left wing struck a fence.

The aircraft skidded to a stop, damaging the left wing and the propeller blades and breaking the nose wheel and windscreen.

During an early morning inspection of Broken Hill Aerodrome, the groundsman discovered an aircraft upside down about 300 m short of runway 23, just outside the aerodrome boundary. The owner was contacted by the local police who advised them that his aircraft had been stolen. Further police enquiries revealed that the owner had actually been the pilot, who now claimed he was suffering from amnesia, possibly caused by a head injury as the aircraft rolled over.

Later the pilot stated that he had departed his property at approximately 2000 CSuT for Broken Hill, with an arrival time of 2016 CSuT. He joined the circuit on downwind for runway 23, reduced engine power and lowered 20 degrees of flap. Turning base leg, he recalled that the engine appeared to be sluggish to throttle movement when an increase in power was required to overcome an excessive sink rate, which he thought may have been caused by the very high temperature of the day. He then retracted the flaps as he was worried that the aircraft might stall. This action probably increased the sink rate.

The aircraft contacted the ground heavily well short of the runway, continued for several metres before contacting obstacles and rolling inverted.

A friend and his family, who had visited the pilot's property that day for a barbeque, reported they had observed the pilot consume about 8 - 10 stubbies of full-strength beer during the afternoon. They departed for their property at about 2000 CSuT, and after about 15 minutes were "buzzed" by an aircraft they believed belonged to the pilot, which then continued in the direction of Broken Hill.

A thorough inspection, and test run of the engine was carried out which did not reveal any faults or malfunctions that may have caused a loss of power. An inspection of the aircraft failed to find any faults which could have contributed to the accident.

The police and the Civil Aviation Safety Authority are investigating further.

The pilot, accompanied by a passenger, was departing from an airstrip which had a dry short grass surface, aligned in an east west direction, and located on the top of a lightly timbered hill. The weather was reported as being fine, with a gusty 10 - 15kt wind blowing from the south-west.

The pilot stated that he had ascertained the crosswind component was within the limits for the aircraft before commencing a take-off towards the west. He reported that the engine power and acceleration were normal, but after becoming airborne he noticed the aircraft appeared to be sluggish, and slow to climb. The automatic wing slats had deployed indicating the aircraft was at, or near its stall speed. He had difficulty maintaining directional control, and the aircraft veered to the right.

He considered rejecting the take off, but as the aircraft was moving with a sideways motion, he decided to allow it to accelerate in ground effect rather than chance a landing which may have impose a side load to the landing gear, and the possibility for it to collapse.

The pilot believed the wind gusts increased and changed to a tailwind component, further reducing the aircraft's climb performance. As the aircraft departed from the airstrip area the pilot was unable to arrest the sideways drift before colliding with a tree.

The aircraft was extensively damaged, and the pilot was unable to turn the fuel off as the selector was inaccessible due to airframe distortion. He evacuated himself from the rear cockpit, then assisted the passenger to exit from the front cockpit. During the evacuation smoke was observed around the front cockpit floor area, which originated from fuel contacting the hot engine and exhaust. The aircraft then became engulfed in flames, resulting in an extensive grass/bushfire.

It is possible that the pilot raised the aircrafts tail too soon at the commencement of the take-off run before effective rudder control could be established. The propeller slipstream direction allows the wash to contact the right side of the rudder imposing a tendency for the aircraft to swing right. This would have been aggravated by the aircrafts slow forward speed, and the crosswind from the left.

The slow airspeed, crosswind, and/or the reported wind changes would have caused difficulties for the pilot to maintain and/or recover directional control.

The glider was being test flown after major maintenance had been completed. During lift off the pilot lost control and the aircraft cartwheeled. The pilot received minor injuries, and the glider was substantially damaged.

Investigation found that the ailerons had been connected in the reverse sense. During the maintenance, reassembly, rigging and preflight the glider had passed through four stages of inspection, all of which failed to detect the incorrect rigging of the ailerons.

It was found that 10 types of glider operated in Australia are fitted with common aileron drive gimbals that can be physically fitted to the incorrect side of the aircraft, thereby reversing the sense of the control.

Immediately after the accident the Gliding Federation of Australia issued an Operations Advice Notice advising details of the accident. The notice made the point that crossed controls had occurred before and that an Airworthiness Advice Notice had been issued in 1980 covering the subject. This notice stated, 'this incident emphasises the dangers of complacency; we have come to expect things to operate correctly and therefore assume that if something is working, it is working correctly'.

The Operations Advice Notice made three recommendations relating to the principles of assuring correct sense and the avoidance of external distraction during preflight inspections.

The Gliding Federation also issued an Airworthiness Directive requiring, on the subject gliders, gimbals for the left wing to be painted bright red and for the gimbals for the right wing to be paint bright green. This action is to be performed at the next annual inspection.

At the conclusion of an 8 hour, 500 km flight the visiting foreign glider pilot was forced to outland 1.5 km short of the airfield. The glider suffered extensive damage consistent with having been landed in a stalled condition with a high rate of descent.

The pilot advised that he was in a lethargic state of mind having mentally relaxed once the airfield was in sight. The operator is looking into visiting pilot dehydration, coupled with fatigue, as a factor in this type of accident.

The purpose of the flight was to assess the student prior to his first solo flight. Preflight fuel contents were 95L, and the pre-take off engine run, which included a carburettor heat check, was reported to have been normal.

The instructor pilot reported that two uneventful circuits were completed. On the third circuit, prior to turning onto the base leg, the student applied full carburettor heat and reduced engine power to 1500 RPM. After turning onto the base leg, the approach appeared too high and engine power was further reduced to 1100/1200 RPM. Turning onto the final leg, the aircraft appeared to be undershooting, and the student was prompted to increase power, but there was no response from the engine. The instructor immediately took control, confirmed that carburettor heat was on, the mixture was rich, and changed the fuel tank selection. However, there was no response from the engine, which continued to rotate at 1100/1200 RPM.

By now, the aircraft was well below the required approach path. The instructor made a brief MAYDAY call and tried to manoeuvre the aircraft to land on a cleared area short of the runway, but the landing gear collided with a 2 m high wire fence. The aircraft cartwheeled sideways before coming to rest. Both occupants were able to escape without injury.

Investigation determined that the engine controls were correctly connected and functioned normally. The carburettor hot air box had been squashed in the accident, and the hot air duct was disconnected. It could not be determined if the duct had detached before, or as a result of, the accident. After removing the hot air box, the engine performed normally during a ground test.

The weather conditions at the time were conducive to severe carburettor icing at descent power. It is likely that carburettor icing occurred during the low power descent and precluded the engine accelerating above idle power on the final approach.