Loss of control

Circumstances:

The pilot had been engaged in sheep spotting for a period of approximately three hours and was returning to the refuelling pad. Enroute, he observed a motorcycle stockman, and landed the aircraft in a cleared area nearby, to advise him of the location of a mob of sheep he had spotted earlier. The pilot advised that after he had landed, he left the engine running at between 70 and 80 percent rotor/engine speed.

Circumstances:

After flying to the resort, the pilot landed the helicopter and picked up a photographer for local area photography. He reported that the initial runs were flown at 500 feet above ground level. During some of these runs the wind changed in direction from north to east and was about 10 knots in speed. The pilot noticed on some occasions, when the wind was a tailwind, it caused control difficulties. On one pass, at about 200 feet above the ground and travelling forward at about 30 knots, the helicopter was again affected by a tailwind. The pilot was unable to prevent it yawing to the right. The rotor rpm decayed, collective was lowered, and the aircraft was flared at about 100 feet, but the sink rate could not be arrested. The helicopter struck the ground at a high rate of descent but remained upright. Evaluation of the flight indicates that the pilot was flying very slowly with a tailwind. He lost directional control, and insufficient power was available to sustain rotor rpm. The pilot later flared the aircraft too high to enable a landing at a safe rate of descent.

Significant Factors:

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

1. The wind was variable in direction.

2. The aircraft was being operated at slow speed and with a tailwind.

3. The pilot lost directional control.

4. The pilot misjudged the height to begin the flare for landing. This accident was the subject of an on-scene investigation.

Circumstances:

The helicopter was flying at about 25 knots and a height of about 75 feet, 10 feet to the left of power lines. The passenger was surveying the wires. As the helicopter approached a tree line, the pilot increased collective. However, rotor RPM decayed, and the helicopter descended rapidly, hitting the ground and rolling over.

Significant Factors:

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

1. The pilot overpitched the main rotor, resulting in a loss of rotor RPM.

2. Insufficient height was available for the rotor RPM to recover before the helicopter struck the ground.

At the conclusion of an aerobatic flight, the pilot intended to practice a number of circuits and landings. Two touch-and-go landings were completed, and the pilot positioned the aircraft for a full-stop landing in 10 knot crosswind conditions. Towards the end of the landing roll, the aircraft commenced to ground loop to the left. The pilot applied corrective rudder and brake, but was unable to arrest the swing. He then applied full power, with the intention of becoming airborne and passing between trees which lined the side of the strip. The aircraft lifted off, but then collided with a tree, fell to the ground, and came to rest inverted. The particular type is known to be difficult to control directionally. It was considered possible that the pilot had relaxed his concentration after the aircraft had touched down.

Circumstances:

The pilot was positioning for a spray run and the aircraft was in the last third of the procedure turn at an angle of bank of about 45 degrees. The aircraft was reported to have overshot the alignment of the next run slightly. One witness said he saw the nose of the aircraft go down. Another witness indicated that the aircraft then rolled under in the turn and struck the ground. The aircraft hit the ground inverted and travelled only about another 20 metres. An explosion occurred on impact and only the left wing and main gear remained unburnt. The pilot was wearing a full helmet, and his harness was correctly worn and fastened. No apparent attempt to egress had been made. Subsequent investigation could find no faults or anomalies with the airworthiness of the aircraft that might have contributed to the accident. Advice provided to the investigation indicates that the Pawnee, at or near the stall in a turn, will stall the lower wing and roll under if aileron alone is used to try and pick up that wing. It was likely that while the pilot was manoeuvring to regain the alignment of the spray run, the aircraft was inadvertently stalled. A draft of this report was addressed to interested parties for consideration prior to release.

Significant Factors:

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

1. The pilot was relatively inexperienced.

2. In an attempt to regain the spray, run alignment, the pilot probably stalled the aircraft.

3. Loss of control occurred at an altitude insufficient for recovery.

The pilot had been requested to carry out an aerobatic display over a fair being conducted at the local racecourse. During the display three spins were completed, with each being entered at about 1500 feet agl and recovery effected by 500 feet agl. The display appeared to be finished when the pilot made a low pass from behind the crowd at approximately 100 feet agl and then climbed out for what looked initially like a normal entry to the circuit at nearby Wyndham Airport. However, as the aircraft approached 1000 feet agl it was observed to carry out a spin entry similar to that used on the three previous spins. A spin to the left started and four turns were completed before recovery appeared to commence at about 200 feet agl. The aircraft struck the ground before recovery was complete, still yawing to the left and with the nose attitude about 24 degrees below that required for level flight. Whether or not the entry to the final spin was delibrate could not determined. The pilot was not approved to carry out aerobatic manoeuvres below 3000 feet agl, however, reports indicate that he had previously conducted low level aerobatic displays.

Due to a loose seat belt banging against the fuselage of the helicpoter, the pilot slowed the aircraft and commenced an approach to land as soon as possible. The chosen approach path had a tailwind of between 15 and 20 knots. Shortly after commencing the approach, the rate of descent increased rapidly and the pilot's application of collective pitch to correct the situation further increased the descent rate. During the approach, both the audio and visual annunciators indicated that the engine had failed. The pilot lowered collective but then had to flare as the aircraft was about to impact a small mulga tree. The aircraft cleared that tree but was damaged as a result of a collision with a nearby tree. The rapid rate of descent experienced whilst descending downwind with a low forward speed is typical of an aircraft which has settled in its own main rotor downwash, i.e in a Vortex Ring State. No defect was found in the engine which might have explained the reported engine failure. It is possible that the pilot inadvertantly selected the throttle to the engine shut-off position as he commenced autorotative flight.

Circumstances:

The pilot reported that after touching down on the third landing for the flight, the aircraft began to turn to the right. Corrective action was taken, however, the aircraft yawed sharply to the left and skidded off the left hand side of the runway. The wind was light and variable at the time of the accident.

The pilot was engaged in a local soaring flight when she judged that an outlanding was necessary. The wind conditions were assessed by observing dust from vehicles on a dirt road and a landing pattern was established. On final approach into a large cleared area, the pilot became aware of an increased ground speed and altered the flight path to land into rising terrain. During the landing, the right wingtip struck the ground and the glider was substantially damaged during the ensuing ground loop. On alighting from the glider, the pilot became aware of strong variable conditions that had induced a tailwind component on landing and probably caused the left wing to lift during the landing roll.

During the fifth touch-and-go landing of a period of solo circuits the student pilot applied right rudder in anticipation of the expected swing as take-off power was applied. The aircraft immediately swung to the right and the student, becoming confused, applied further right rudder pressure. The aircraft left the runway and impacted a ditch outside the flight strip. The pilot was not using the sash component of his seat belt and he suffered a facial laceration when he struck the instrument panel during the impact.