Loss of control

The operator of the aircraft had contracted to spray 160 hectares of barley with weed killer. On arrival over the property, the pilot flew an inspection orbit and commenced spraying the first paddock towards some tall trees and a powerline. After this first pass the aircraft was pulled up into a procedure turn before diving steeply over the same obstacles, in the reciprocal direction. When the aircraft was clear of the obstructions, the pilot attempted to level the aircraft for the next spray run. However, the aircraft continued along its established flight path until striking the ground in a pronounced nose high attitude. The impact damaged the propeller, spray booms and landing gear. Chemical sprayed over the windscreen depriving the pilot of forward vision, and he was unable to control the subsequent landing run sufficiently to prevent the aircraft from broadsiding. The aircraft was being operated at a weight in excess of the Agricultural Gross Weight and at a relatively slow airspeed. During the pullout from the dive, the load factor ("G" loading) applied to the aircraft caused an aerodynamic stall. The pilot was unable to effect a recovery at such a low altitude.

Circumstances:

Some months prior to the accident the pilot had begun learning to fly ultralight aircraft. Around this time, he also began to have spells where he was able to see and hear people but could not move or talk to them. His instructor recommended that he stop flying and complete medical tests. The pilot later purchased and assembled a gyrocopter. Over a two-month period he learned to fly the craft. On the morning of the accident, he asked a more experienced gyrocopter pilot to fly his machine and check its characteristics. The other pilot found that it was quite satisfactory. Those who had observed the pilot flying previously considered that he had no problems in controlling the aircraft. The gyrocopter was observed on final approach, but it then disappeared for a short time, having flown an orbit to the left. After adopting a final approach for the second time the gyro flew towards the strip at about 50 knots. A witness observed the craft roll to the left from a height of about 30 feet. The gyrocopter impacted the ground in a left bank of about 130 degrees. No evidence of pre-impact failure of the aircraft was found.

Significant Factors:

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

1. The cause of the accident was not positively determined. It is possible that the pilot suffered a temporary incapacitation during the approach.

Recommendations:

1. That the Civil Aviation Authority undertake, or oversee, an education campaign intended to remind sport aviation pilots of the need to consider their standard of health before undertaking flying activities.

When the aircraft arrived in the destination area, another aircraft was also in the circuit. The pilots were in communication with each other, and arranged that VH-CUO would land after the other aircraft. However, the pilot of VH-CUO apparently misjudged the relative speeds of the two aircraft. He initiated a go-around from a position on final approach to runway 15, when there was evidently insufficient separation with the preceding aircraft to allow a normal landing. The aircraft remained at a low height above the ground, and the pilot broadcast a message that he intended to land in the opposite direction, on runway 33. The wind at the time was from the south-east at about 10 knots. Witnesses observed the aircraft as it tracked along the western side of the runway. The turn onto base leg was made at an angle of bank of about 60 degrees, and about three-quarters of the way around the turn, the nose of the aircraft dropped rapidly. The aircraft then dived steeply to the ground, and was destroyed by the impact and subsequent fire. The subsequent investigation did not reveal any defect or malfunction which might have affected the operation of the aircraft. The pilot was conducting an operation known as a "bank run", and there is pressure on pilots performing such runs to adhere to the prescribed schedules. The pilot's decision to perform a low level circuit and land downwind was considered to be related to his desire to arrive at the terminal as close as possible to the scheduled time. While conducting the circuit, the aircraft stalled during a turn at a height which was too low to allow the pilot to recover control before impact with the ground.

During the flight the pilot reported that he would descend to cruise at 500 feet above ground level. Witnesses saw an aircraft at low level on the expected track, and others heard aircraft noise and then the sound of an impact. Weather conditions were overcast with low cloud covering the hills. The wreckage was found at an elevation of about 4300 feet above mean sea level. The aircraft had apparently struck the ground while in a steep nosedown attitude and rotating to the right. A fire had broken out and engulfed the wreckage. Investigation did not reveal any defect or malfunction of the aircraft which might have contributed to the development of the accident. Both engines were operating at high power settings and the gear and flaps were up. The aircraft had been operating under the Instrument Flight Rules when the pilot reported his intention to descend. Conditions at the destination were suitable for visual flight, and the reason the pilot elected to proceed at a low height above the ground was not determined. It was likely that while cruising below the cloud, the pilot was suddenly confronted by localised adverse weather conditions in the vicinity of the accident site. The maintenance of control of the aircraft under these conditions should have presented little problem to the pilot, who was suitably qualified to operate in instrument conditions. In these circumstances, the precise sequence of events leading to the evident loss of control of the aircraft could not be established.

No Summary

The aircraft had previously had to be flown with the control stick displaced to the right of centre in order to maintain a wings level attitude. The aircraft owner advised a visiting ultralight pilot of the problem, who offered to attempt rectification. After conducting a flight to experience the problem first hand, the pilot adjusted the right wing warping wire and conducted another test flight. The adjustment had improved the trim problem but still not completely provided a fix. The pilot then readjusted the right wing warping wire to its original condition and added a D-shackle to the left wing warping wire to increase its length. Another test flight was carried out and it was found that the aircraft could only be maintained in level flight when full right rudder and full right control stick were applied. The aircraft was struck by a wind gust and the left wing dropped, as no further control was available to correct this situation, the pilot pulled a wing warping wire. Unfortunately he pulled the right wire instead of the left wire and was unable to correct his error before the aircraft struck the ground. A subsequent inspection of the wreckage found that the right wing warping wire was 19 millimetres longer than the left. Also, all the dimensions of the right wing were slightly larger than that of the left wing, resulting in the right wing area being about 80 square centimetres greater.

While conducting a cross-country flight, the pilot encountered deteriorating lift conditions, and an outlanding became necessary. The pilot reported that while he was on short final approach to the selected paddock he encountered strong lift, which caused him to overshoot the target touchdown point. During manoeuvring for another approach, the glider stalled and struck the ground in a very steep nosedown attitude. When it was apparent that the aircraft would overshoot the target touchdown point, the pilot had carried out a steep turn to re-position for final approach. During this manoeuvre the spoilers, flaps and landing gear had been left extended. The pilot had evidently not monitored the airspeed and the glider had stalled and probably entered an incipient spin. There had been no requirement for the steep turn to be undertaken, as a landing straight ahead was available.

The pilot was participating in a 500 kilometres cross country gliding competition. Atmospheric conditions were not favourable for prolonged soaring flight, and none of the other participants was able to cover any significant distance. However, this particular aircraft departed on the planned track, and the next reported sighting was about 3 kilometres from the accident site. At this time the aircraft was circling at approximately 300 feet above the ground and tracking to the north-west. No further sightings were reported, and the wreckage of the aircraft was subsequently discovered in a paddock 102 kilometres from the DEPARTURE aerodrome, on the intended track. Investigation revealed that the glider had initially contacted the ground with the leading edge of the right wing, while the aircraft was in a steep nose-down attitude and spinning to the right. There were no known witnesses to the accident, and it could not be established whether the pilot had been attempting to outland or to find a thermal at low level. There was no evidence of any pre-existing mechanical defect which might have contributed to this occurrence. It was probable that control of the glider was lost during a manoeuvre at low speed and height above the ground, however the reason for the loss of control was not determined.

The purpose of the flight was to convey the three passengers to Casino for business. Prior to departing Scone the pilot telephoned Sydney Operational Control Centre Briefing Office and submitted a flight plan which indicated that the flight would be conducted in accordance with Visual Flight Rules (VFR) and proceed via Upper Bowman and Taree at 7000 feet above mean sea level (amsl) to Port Macquarie and then Casino.

The pilot also indicated when submitting the flight plan that no radio navigation aids were fitted to the aircraft. The pilot then received a briefing on the weather conditions that could be expected along the route to be flown. The winds were given as generally southerly at about twenty knots with the cloud as scattered stratus between 1000 and 2500 feet and areas of broken strato-cumulus between 2000 and 6000 feet amsl. At 0740 hours the pilot advised Sydney Flight Service (FS), by radio, that the aircraft had departed Scone at 0733 and was climbing to 7000 feet. At 0809 the pilot reported the aircraft's position at Upper Bowman, cruising at 7000 feet and estimating Taree at 0829. Twelve minutes later the pilot of another aircraft also bound for Taree contacted VH-UDX and asked the pilot to confirm the aircraft altitude as 7000 feet. The pilot of VH-UDX replied that his aircraft was at 6500 feet on descent to 5000 feet and that he had run into a bit of "murk". When questioned further by the other pilot and Sydney FS the pilot reported VH-UDX was at 6000 feet in cloud and requested the visibility at lower altitudes. The pilot was advised that the cloud base at Williamtown was 3000 feet and he then reported that he intended to back track to Scone. The pilot was then requested to activate the transponder fitted to the aircraft and VH-UDX was subsequently identified by radar 18 nautical miles south-west of Taree at 0828 hours. The pilot was advised of this position and reported his heading, which indicated the aircraft was tracking towards Scone. During the next few minutes Sydney FS obtained information from the pilot relating to fuel endurance; estimate for Scone; altitude and cloud conditions.

The last communication received from the aircraft was at 0838 when the pilot acknowledged an instruction to call Williamtown Approach (for radar assistance). Further communication attempts were unsuccessful. At about 0840, residents of Gloucester heard the sound of an aircraft engine, apparently at high power, moving from the west to the north of the town. They could not see the aircraft. At the time there was dense cloud overhead, base about 800 feet above ground level (elevation 350 feet amsl), with drizzle. The aircraft appeared suddenly, descending steeply from the base of the cloud. The nose rose momentarily then the left mainplane folded back against the fuselage, separated and dropped away. The empennage separated from the fuselage. The fuselage with the right wing attached struck the ground in a park on the western edge of the town. The left wing, empennage and some other debris landed several hundred metres to the north east of the main wreckage.

Subsequent investigation did not reveal any pre-existing fault with the aircraft that could have contributed to the accident. The weather conditions that were encountered by the pilot were substantially as forecast and relayed to the pilot during the pre-flight briefing.

Circumstances:

The pilot purchased the aircraft in kit form from the manufacturer when he was visiting the USA in June 1989. He completed a training course in the dual seat version comprising approximately 30 hours of dual instruction and was certified competent for solo flight on 10 June 1989. After returning to Australia, he assembled the aircraft with the assistance of an aircraft engineer and began flying it on 20 September 1989 and had flown approximately 5 hours since then. On the day of the accident, the pilot had been practising take-offs and landings at the Tully aerodrome, and after about an hour of flying stopped for a break and to check the fuel. During the break he said that he would fly for another half hour and then stop to refuel and have something to eat. During the next flight, the aircraft was seen proceeding along the runway and carrying out "S" turns to reverse direction. During the commencement of a turn to the right, whilst heading towards the southern end of the strip, the aircraft was seen to adopt a steep nose down attitude, and dive towards the ground. The aircraft impacted the ground inverted, adjacent to the strip on a heading of 200 degrees magnetic and travelled 15 metres after initial impact before coming to rest. There was no evidence to suggest that the aircraft was operating abnormally prior to the accident sequence, and no defects were found which may have contributed to the development of the accident. The aircraft pitched nose down suddenly, and the rotor blade struck the tailfin with considerable force before ground impact. The behaviour of the aircraft is consistent with that which may occur when a gyrocopter is subjected to zero or negative "g", causing normal inflight forces to become unbalanced, and the gyrocopter to become uncontrollable. The weight of the aircraft is removed from the rotor, and the engine thrust may then turn the aircraft upside down. This could be caused by levelling off from a climb too abruptly at a low forward speed and allowing the airflow through the rotor to be reversed.

Significant Factors:

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

1. The pilot was inexperienced and was teaching himself to fly the gyrocopter without the supervision of an instructor. His previous training was thorough, but its effectiveness was diminished by lack of continuity during the following 3 months.
2. The loss of control is considered to be due to misapplication of controls leading to a zero or negative "g" situation. The possibility of a wind gust or willy willy causing an upset was considered, but there was no such observation by witnesses, and the wind at the time of the accident was light and variable.
3. The longitudinal stability of the aircraft is dependent on the balance of forces, in the absence of a horizontal stabiliser. The aircraft was not fitted with a horizontal stabiliser which would have improved longitudinal stability and reduced control sensitivity.

Recommendations:

1. The Civil Aviation Authority should consider the introduction of two place gyroplanes for use in a training role. At the moment there is no avenue in Australia for such training and the number of accidents involving inexperienced pilots is significant. It is recommended that CAO 95.12 be amended to include dual place gyroplanes, and that a syllabus of training be specified similar to the FAR 61.85 requirements.
2. The Civil Aviation Authority should consider the establishment of a scheme, to assist the Australian Sport Rotorcraft Association to set up a training and checking system, which would be available to members in specified areas of each State where this activity is popular.