Loss of control

Towards the end of a 4 hour competition flight, the pilot realised that the aircraft would not reach the finishing line and that an outlanding would be necessary. After establishing the aircraft on final approach to the selected paddock, the pilot noticed a pile of stones obstructing the target touchdown area. While manoeuvring to avoid this obstruction, the left wing of the aircraft struck the ground and a ground loop ensued. The pilot had been suffering the effects of a head cold and sinus infection, and had probably become fatigued during the flight in demanding conditions. He had persisted in his efforts to reach the finish until the glider was too low to allow a more suitable paddock to be selected for the outlanding. This accident was not the subject of an on-site investigation.

The pilot stated that a characteristic of the strip in use was that there existed off the north-eastern end an area of downdraught caused by prevailing wind blowing over the adjacent terrain and trees. To counteract this downdraught it was necessary to climb to at least 150 feet above the ground level prior to overflying the end of the strip. On this occasion, the pilot believed sufficient altitude had been gained after takeoff, and turned to the left to take advantage of the upgoing air. However, the aircraft encountered a downdraught and the pilot reported that he allowed the airspeed to get too low and the aircraft enetered a spin to the left. During the recovery attempt the aircraft entered a spin to the right and complete recovery was not achieved before ground impact.

The aircraft had been refurbished during the preceding months, and at the completion of this work the pilot intended to carry out a short test flight. He subsequently reported that as soon as the aircraft became airborne after a normal take-off roll, it veered sharply and the right wing dropped. Corrective control inputs had no effect, the wing and propeller struck the ground and the aircraft overturned, coming to rest about 200 metres from the start of the take-off roll. The surface wind was reported to be varying up to 30 degrees off the runway direction, and gusting up to 15 knots. Because of the degree of damage sustained however, it was not possible to determine whether the wind conditions or the rigging of the aircraft was the major factor contributing to the accident.

Arrangements had been made for three Tiger Moth aircraft to carry out a fly-past at Walcha as part of celebrations to commemorate the first Australian superphosphate spreading operation by air. Earlier in the day VH-BII was flown from Williamtown to Maitland and Scone, where all three aircraft were refuelled in readiness for the flight. The pilots briefly discussed the flight procedures to be used enroute to Walcha and agreed that the pilot of the aircraft planned to take-off last would be responsible for navigation for the group. There was little or no discussion about how the aircraft would form up after take-off prior to departing on track. The aircraft were positioned for take-off with VH-BII planned to be the second of the group to become airborne. The first aircraft took off normally and commenced a left turn when at a height of about 500 feet. VH-BII was observed to follow a similar pattern, however the third aircraft commenced a right turn after take-off to intercept the track to Walcha. Shortly afterwards VH-BII, which had made a gradual turn to the left through about 45 degrees was observed to rapidly enter a steeply banked turn to the right. The angle of bank increased and the aircraft entered a spin. Any recovery action attempted by the pilot was unsuccessful and the aircraft struck the ground in a steep nose-down attitude after passing through a set of power lines. Fire broke out immediately and engulfed the wreckage. Subsequent investigation did not disclose any defect or malfunction of the airframe, engine or systems of the aircraft which might have affected the pilot's ability to safely control the aircraft.

This flight was to be the pilot's first flight in a minimum aircraft. He was briefed to carry out a take-off and landing along the beach. When the aircraft became airborne a left bank was adopted and right rudder was used to attempt to regain directional control. As speed was increased directional control was achieved but oncoming obstructions made further manoeuvring necessary. After starting to climb, directional control was lost. The aircraft crashed into trees and caught fire. The pilot mentioned to his rescuers that the ailerons had been inoperative. The pilot later succumbed to his injuries in hospital. Investigation of the apparent aileron failure was hampered by the degree of fire damage to the aircraft. This damage was a result of the inability of the plastic fuel tank to withstand the impact with the ground. The precise cause of the accident remains undetermined.

Because of strong crosswind conditions at his planned destination the pilot diverted to a nearby strip which was aligned into the prevailing wind. Although the groundspeed was low during the approach the pilot elected to use full flap for landing. Shortly after touchdown the left wing lifted and the pilot was unable to apply full corrective aileron because his knee became jammed between the control column and the flap lever. The aircraft ran off the side of the strip and struck a fence. The fence was only 28 metres from the centre-line of the strip. In his efforts to apply full aileron the pilot had lifted his left foot from the appropriate rudder pedal, which probably increased the tendency of the aircraft to diverge to the right of the strip.

Circumstances:

The pilot had received winch launch training eighteen months earlier but had not carried out any further launches until the day of the accident. His flying experience on the Libelle was restricted to two flights, some four months earlier. On the day of the accident, he underwent three winch launch check flights with a club instructor in a K7 glider, resulting in a satisfactory standard being assessed. It was reported that the pilot then prepared for a winch launch in the Libelle, which included selecting full nose down elevator trim to counter an expected nose up pitch tendency during launch. Shortly after the glider became airborne, the nose pitched up very steeply, the right wing dropped and struck the ground, resulting in the glider cartwheeling into a fence.

After flying in the local area for a time, the pilot entered a long straight-in final approach for the easterly strip he had used for take-off. From a distance he observed that the wind was a light southerly. Following a slight bounce on touchdown, braking was initiated but the aircraft seemed to be travelling faster than normal. The pilot, believing that he had landed with a tail-wind, turned the aircraft to the north-east to increase the landing roll available. The aircraft overran the area into a fence and firebreak. The approach speed used was 12 knots faster than that recommended in the landing chart. The bounced landing, slippery grass surface and use of other than maximum braking increased the stopping distance required. The direction of turn chosen by the pilot to increase his stopping distance was downhill and with a tailwind component. The presence of telephone lines at the end of the strip precluded a go-around.

The pilot was conducting superphosphate spreading operations in fine and clear weather conditions. The paddock being treated sloped uphill, and there were heavily timbered peaks beyond the paddock. The pilot had spread the paddock the previous day under similar conditions. On this occasion the aircraft was apparently performing normally as the first swath run was completed, but the aircraft did not appear to gain any appreciable height as it approached the hills. It was then seen to adopt a steep nose-up attitude and commence a wingover type manoeuvre. During this manoeuvre the aircraft struck trees and then impacted the ground. A fierce fire broke out and engulfed the wreckage. Although the investigation was hampered by the extensive fire damage, no defect or malfunction was discovered which might have contributed to the accident. The reason the pilot, who had extensive agricultural experience, chose to conduct swath runs towards steeply rising ground was not determined. The wind direction had changed since the previous day, and the aircraft was likely to have been affected by downdrafts on the lee side of the hills. When the pilot realised the aircraft was not performing as expected, he evidently attempted to dump the remaining load and reverse the direction. However, there was insufficient aircraft performance available to successfully complete this manoeuvre.

On arrival at a sloping helipad, the pilot overflew the pad to ascertain that it was clear, and made a final approach to the pad. During the landing two of the main rotor blades struck the surface of the slope. The investigation was carried out by the Department of Civil Aviation Malaysia.