Loss of control

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.

The pilot was departing into strong and gusty wind conditions. The aircraft was observed to climb steeply to about 200 feet above ground level. It then entered a descending turn to the right, at a low airspeed. The descent continued with the aircraft in a nose high attitude, and a wing was seen to drop shortly before ground impact. The pilot subsequently reported the engine was delivering full power throughout the flight. Another pilot who had flown a number of flights in the area during the day, reported that he had encountered pronounced areas of sink to the north of the strip. It was considered that while attempting to fly out of similar conditions, the pilot had allowed the airspeed to decay and the aircraft had stalled. There had been insufficient height available for the pilot to effect recovery. This accident was not the subject of an on-scene investigation.

Circumstances:

The pilot was undergoing a check flight with an instructor, as he was contemplating purchasing this type of aircraft. This was the first occasion that the pilot and instructor had flown together. A series of exercises was carried out, during which the pilot was asked to demonstrate a power on stall at a height of approximately 500 feet. During this exercise, the pilot did not lower the nose sufficiently during the recovery. The pilot was not accustomed to practising stalling at such a low altitude, and during his previous training this had been carried out at 1500 feet. After some discussion another stall recovery was carried out, and on this occasion the pilot used the correct technique. The instructor then decided to return to the strip to carry out some circuits and landings as he assessed the pilot to be unsuitable to fly solo. The flying technique required by the instructor was generally at variance to that previously experienced by the pilot, and it would appear that the check flight was rather vigorous without the opportunity to become accustomed to the environment. During the return flight, the instructor described the circumstances which could cause the aircraft to stall during a forced landing with no power. To demonstrate this, he then closed the throttle at a height of between 300 and 500 feet, and asked the pilot to adopt a glide attitude, initiate a stall and then effect a recovery without the use of engine power. The pilot did not lower the nose sufficiently after the stall symptoms appeared, and he was told to further lower the nose, as a steep nose down attitude is required to effect this type of recovery. When the pilot did not commence to ease the aircraft out of the ensuing dive, the instructor called that he was taking over, but he was unable to move the controls. The pilot had become rigid at the controls, the instructor was unable to correct the situation, and the aircraft remained in a pronounced nose down attitude until ground impact.

Significant Factors:

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

1. The instructor was carrying out stalling practice at a low height.

2. The pilot mishandled the controls, probably due to misapprehension.

3. The pilot apparently panicked and became rigid on the controls when the aircraft was in a steep nose down attitude near the ground.

4. The instructor was unable to regain control of the aircraft before it struck the ground.

Recommendations:

The Civil Aviation Authority in conjunction with the Australian Ultralight Federation, should consider specifying minimum heights above ground level for ultralight aircraft engaged in stalling, spinning and unusual attitude recovery practice.

After takeoff, the aircraft was observed to accelerate at a low height above the strip. At the upwind end, the pilot initiated a steep climb and a steep turn to the right, however the aircraft stalled at about 150 feet above the ground. The aircraft struck the ground heavily and slid into a ringlock fence. The pilot freed himself from the wreckage, and the engine which was still running at high speed, was shut down by a spectator. The pilot reported that after the ultralight stalled, he had the stick full back, but the aircraft would not recover. The aircraft stalled as a result of the steep climbing turn but recovery was not effected due to incorrect stall recovery technique.

Analysis of a video recording taken of the take-off run by the occupant of the front seat, indicated that the aircraft became airborne after a ground roll of about 18 seconds. The aircraft then continued in the direction of takeoff for a further 11 seconds at what appeared to be near to takeoff speed. The aircraft did not climb away. It was not clear from the recording whether or not the aircraft was airborne throughout the 11 seconds. At the end of this time however, the aircraft was on the ground and it then veered sharply to the right. At the time the prevailing wind was a left quartering crosswind. The pilot was unable to regain directional control and the aircraft ran off the side of the strip and struck an embankment before coming to rest inverted. No defect was found with the engine or flight controls and the aircraft weight and centre of gravity were within the required limits. The aircraft had been fitted with a braking system and had recorded 27 hours in service since the modification. An examination of the brake shoes revealed an excessive rate of wear to the left brake shoes, and a cable within the braking system was found to be incorrectly adjusted. However, whether these defects contributed to the development of the accident could not be established. The reason for the loss of directional control was not determined.

During the takeoff run, the pilot reported that the aircraft encountered a crosswind from the left. Despite the application of left rudder and aileron the aircraft continued to drift towards the right of the strip. The pilot attempted to manoeuvre the aircraft over a gable marker but one of the mainwheels struck the marker and caused the aircraft to turn further to the right. The aircraft continued and the lower right wing was torn off after it struck a fence post. The aircraft came to rest 13 metres beyond the boundary fence. During the takeoff the wind velocity had changed appreciably and the aircraft had drifted well to the right of the strip before the pilot had attempted to take corrective action. The takeoff was not abandoned until after the aircraft had struck the fence.