Loss of control

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.

The pilot was making a landing approach in 8 knot crosswind conditions. Witnesses reported that the aircraft was flared at a greater height above the ground than normal, and it subsequently landed heavily and bounced. The pilot elected to carry out a go-around, applied full power and raised the flaps. Shortly afterwards, the aircraft stalled and struck the ground in a left wing low attitude at about 90 degrees to the runway heading. The pilot had not flown for several weeks, and had evidently misjudged the height of the aircraft when he commenced the landing flare. After he applied full power to go-around, he had retracted the flaps while the airspeed was still relatively low.

The aircraft was being flown at about 200 feet above ground level in a left turn while the pilot was attempting to locate some sheep. The pilot reported that the aircraft stalled and that during the recovery it struck a bush. This resulted in damage to the right mainplane, right wing strut, right horizontal stabiliser and the brake lines on both mainwheels. The pilot was able to maintain control of the aircraft and land at a nearby airstrip. The pilots attention was diverted from the operation of the aircraft whilst he searched for the sheep and directed the ground party. He had been working long hours and was only obtaining about 4 hours sleep each night and considered that fatigue was a factor in his allowing the airspeed to decay unnoticed.

In the latter stage of the landing roll the aircraft encountered a strong gust of wind from the right. The aircraft swung suddenly to the right and the pilot was unable to maintain directional control. The left maingear leg bent and the airframe distorted, allowing the left door to become dislodged. The aircraft came to rest on the runway, after having groundlooped through 130 degrees. Before landing the pilot had carefully monitored the Aerodrome Terminal Information. He was fully aware of the possibility of occasional wind gusts resulting in a maximum crosswind component of 15 knots, which is 2 knots above the maximum limitation for the aircraft. Also he was prepared to conduct a go-around should he have encountered any problems during the approach and flare during the touch down. It is also probable that the pilot relaxed his concentration too early during the landing roll, in anticipation of completing the day's flight.

The pilot deposited the sling load of delicate instruments on the ground. To avoid dropping the shackle on the load, and because of the proximity of a hangar to the left, he moved the helicopter to the right. The movement, together with type of shackle used and the design of the hook, resulted in the load not being released. Prior to the flight the pilot had not insisted on the fitment of external load observation mirrors. While leaning out of the helicopter to check that the load had been released, he inadvertently caused the helicopter to move further to the right. The resulting tension on the cable connecting the hook and the load induced dynamic rollover. The pilot attempted unsuccessfully to correct the roll and during the subsequent landing the main rotor struck the ground. Use was not made of an available and qualified marshaller.

Circumstances:

The pilot, who had limited experience on the Bell 47, attempted to bring the aircraft to a quick stop at approximately 50 feet above ground level. During the manoeuvre, the cyclic control reached its forward stop. The pilot lowered the collective control in an attempt to recover the situation however his inexperience caused him to lose full control of the aircraft. The tail rotor struck the ground before the pilot was able to regain control. The subsequent landing was heavier than normal.