Loss of control

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.

Shortly after touchdown the pilot noticed a kangaroo on the side of the strip. He considered that more of the animals might be in the vicinity, and elected to carry out a go around. Full power was applied and the aircraft became airborne, but almost immediately afterwards the pilot changed his mind and decided to continue with the landing. When power was reduced again, the aircraft stalled and landed heavily. The nosegear subsequently dug into the surface of the strip and the aircraft overturned. After applying power to go around, the pilot had not monitored the airspeed and the aircraft had stalled at a low height above the strip.

Circumstances:

The pilot had not previously flown the homebuilt floating hull type amphibian aircraft. The flight was to carry out an evaluation of its water handling characteristics, before continuing with the flight testing for the issue of a Certificate of Airworthiness. The pilot reported that the water conditions were calm with a light easterly breeze blowing. A witness had observed power boats in the area where the aircraft was operating, churning up the water surface. This type of aircraft has a known tendency to "porpoise" in choppy surface conditions. Several high-speed taxi runs were performed, both into wind and crosswind. The pilot reported that the aircraft had a tendency to swing to the left, otherwise operations were normal. He returned to the beach where he had the water rudder alignment checked. After several more high-speed taxy runs the pilot considered that the aircraft was ready for flight. During the take-off and before the aircraft had obtained flying speed, it passed through the wake of a power boat, causing its nose to pitch up and left wing to drop. The pilot released some up elevator pressure and used right aileron to correct the roll. This had little effect in correcting the aircraft attitude before it encountered a second wave, pitching the nose up higher and increasing the roll to the left. The left hand wing float impacted the water causing the aircraft to swing to the left and the nose to drop. This was followed by a severe water loop to the left, which submerged the cabin momentarily and caused the left hand wing float, nose gear door and rudder to separate. Previous flight testing of this type of aircraft had shown that the ideal take-off technique was to maintain the aircraft level, with the elevator control held in the neutral position. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. The pilot attempted to take-off using a less then optimum control technique.

2. The aircraft was affected by adverse water conditions.

3. A loss of control occurred before the aircraft had reached flying speed.

The pilot, who did not hold an instructor rating, was conducting a trial instructional flight. Prior to DEPARTURE, he had briefed the passenger on the functions of the various controls in the helicopter. On the downwind leg of the circuit, the passenger was allowed to handle some of the controls. The aircraft was subsequently placed in a hover at about five feet above the ground, and the passenger was invited to attempt to control the helicopter by use of the anti-torque pedals and the cyclic control. The passenger overcontrolled the aircraft, and the pilot was unable to prevent it from striking the ground in a steep nose-down attitude. Following the impact a fire broke out and destroyed the aircraft. No mechanical fault was subsequently discovered which might have led to the development of the accident. The pilot had undertaken the flight because no qualified instructor had been available at the time the passenger arrived, and he wished to avoid potential embarrassment to the company.

A road accident victim required urgent transport to a hospital offering specialist facilities for her particular condition. Road transport by a suitably equipped intensive-care ambulance was not available, and a decision was taken to employ a helicopter. When first contacted, the pilot expressed doubt about the feasibility of using the helicopter because of adverse weather conditions in the area. Some 30 minutes later the pilot was again contacted and requested to undertake the flight. He agreed, subject to weather conditions being suitable, and prepared for the flight from Wollongong to the hospital at Bowral where the patient was being held pending transfer to Sydney. The pilot, accompanied by a crewman and a paramedic, departed Wollongong at 0027 hours local time. As the aircraft approached Bowral, deteriorating weather conditions were encountered. Arrangements were then made through the ambulance radio network for the patient to be transported to Wilton, where the pilot landed shortly after 0100 hours. The patient arrived about 20 minutes later and DEPARTURE for Sydney was made at 0153 hours. When the pilot contacted Sydney Flight Service he was advised that the Control Zone was closed to visual operations because of low cloud. The paramedic considered that the flight should continue because of the patient's condition, and the pilot declared a mercy flight. He was cleared to continue on an emergency basis, with radar directions being provided to assist navigation. The reported cloud base at Sydney Airport was 300 feet, and the night was dark, with no moon. At 0212 hours the pilot reported that the aircraft was running into cloud, and he would hold over Parramatta. No further transmissions were received from the aircraft. Shortly afterwards it was discovered that the aircraft had crashed on the tidal embankment of the Parramatta River. A subsequent detailed examination of the wreckage revealed no mechanical defect or malfunction which might have made an accident inevitable. It was considered that the accident probably resulted from a loss of control of the helicopter during a turn away from an area of low cloud. Neither the aircraft nor the pilot was approved for flight in other than visual conditions, and the pilot probably became disoriented either from the loss of the visible horizon, or by reference to a false horizon. It was evident that he was in the process of regaining control, but insufficient height was available to complete the recovery before impact with the ground.

The pilot brought the helicopter to a hover at 1000 feet agl, pointing approximately into wind. The aircraft began to yaw to the right and the pilot was unable to stop the resulting rotation. The helicopter descended in a steep nose down attitude and struck the ground heavily while still rotating to the right. The landing skids were torn off and the helicopter came to rest on its left side. No mechanical fault or defect was found with the helicopter which might have contributed to the development of the accident. It was considered likely that the aircraft experienced the phenomenon known as "tail rotor breakaway", which results in an uncommanded yaw to the right accompanied by a steep nosedown pitch change. The pilot was aware of the phenomenon, and had read various articles on the subject. However, much of the information available at the time was of a confusing and conflicting nature, and the recovery action employed by the pilot on this occasion was ineffective.