Loss of control

The pilot had been operating the aircraft on gypsum spreading operations in mountainous terrain during the morning. The task involved flying along a valley, crossing a ridge at the head of the valley and spreading the gypsum on the western slopes of the ridge. Shortly after the aircraft departed on the accident flight, smoke was observed rising from the valley. It was discovered that the aircraft had impacted the side of the valley with a high rate of descent and very low forward speed. The hopper load had not been jettisoned prior to impact and the hopper doors were closed. The aircraft was destroyed by impact forces and the subsequent fire. The investigation did not reveal the presence of any pre-existing mechanical defect which might have contributed to the accident. The engine was operating at high power at the time of impact. Because of the damage to the aircraft, the hopper and fuel loads were not able to be precisely determined. Evidence suggested that the aircraft was probably heavier than the maximum all up weight approved for agricultural operations. On previous flights the aircraft had been observed to orbit over the valley in order to gain sufficient height to safely clear the ridge. It is considered possible that on this occasion the pilot commenced the orbit from a position and height which did not allow sufficient room for the manoeuvre to be completed at moderate bank angles. It was evident that during the orbit the aircraft stalled and entered an incipient spin. Insufficient height remained to permit recovery before impact with the ground. The weather conditions at the time were conducive to the formation of downdrafts, but whether this phenomenon had any bearing on the loss of control leading to the accident was not established. In addition, the reason that the hopper load was not jettisoned could not be determined.

Circumstances:

The aircraft was engaged in circuit training in the 05 direction. Wind conditions were reported to be 030/5 to 8 knots and gusty. A number of normal take offs and landings were safely executed before the instructor attempted a downwind take-off in the 23 direction. The aircraft was observed to take a longer than normal ground roll. When it reached a height of about 50 feet the left wing dropped, and the aircraft commenced to rotate to the left before striking the ground in a steep nose down attitude on a heading of about 050 degrees. A witness who was standing near the north eastern end of the strip said the wind gusted to about 15 knots from the north east immediately prior to the accident. It would appear that during a critical stage of the take-off, the aircraft stalled after suffering a sudden a loss of airspeed associated with a significant wind shear. This accident highlights the dangers of attempting downwind take-offs in ultra-light aircraft.

Recommendations:

It is recommended the AUF publicise the circumstances of this accident to highlight the dangers associated with downwind take offs in ultra-light aircraft.

At 0341 hours EST on 6 July 1989, Beech 70 Queenair aircraft registered VH-XAE collided with high voltage power lines and descended rapidly, contacting the ground three kilometres north-east of Tolmie. The pilot, who was the only occupant, received fatal injuries. There was no fire. The aircraft was on a flight from Sydney to Melbourne cruising at 8000 feet. Persons in the accident area heard an aircraft flying very low over their houses, then observed a flash of light and heard the sound of ground impact. A ground search was commenced but due to falling snow and very poor visibility the wreckage was not found until about 0745 hours in daylight. The elevation of the ground at the accident site was approximately 2700 feet above sea level. The accident site was located at co-ordinates 36`55'south, 146`17'east.

A series of demonstration flights had been arranged by the aircraft owner. The weather was clear and sunny, with occasional wind gusts up to about 5 knots. Thermal activity was reported in the area. The pilot was the manufacturer of the aircraft, which was sold in kit form. Although he had considerable experience on the aircraft type, he was not familiar with flight in thermalling conditions. After conducting three short demonstration flights with a passenger on board on each occasion, the pilot arranged with the owner to carry out a solo flight to gain thermalling experience. Witnesses reported that the ground roll appeared to be normal, but the aircraft commenced a turn at about 10 feet above the ground while climbing at an unusually steep angle. After the aircraft had reached a height of about 100 feet the climb angle was seen to steepen further, and shortly afterwards the left wing dropped and the aircraft entered a spin. The rotation ceased after one and a half turns with the aircraft then in a steep nose-down attitude. Recovery from this dive was apparently being made when the aircraft struck the ground. No evidence of any mechanical failure or defect was subsequently found. It was considered probable that the unusually steep climb attitude was the result of either the pilot's wish to demonstrate maximum performance, or the unexpected effects of a thermal. The pitch-up which occurred before the stall and subsequent spin was possibly related to the thermal activity.

Circumstances:

The aircraft was taking off from a short strip. Soon after take-off the aircraft banked to the left lost airspeed and struck the ground. The pilot who was seriously injured was not sure if the propeller at the rear had struck long vegetation at the end of the strip causing him to lose control or if the aircraft had stalled during the turn.

After a normal circuit the aircraft crossed the threshold at 85 knots. The pilot advised that the wheels locked as soon as braking was applied. Intermittent brake application had little effect in slowing the aircraft and as the pilot considered that insufficient strip remained to permit a go-around he attempted to ground loop the aircraft. It slid off the side of the strip and collided with a fence before coming to rest. The strip surface was very slippery as a result of overnight rain. Misty rain was still falling as the pilot made his approach and touched down about one quarter of the way along the strip. The pilot had not determined the last point at which a go-around could be commenced and persevered with the landing attempt beyond the point where a go-around could have been safely accomplished.

Circumstances:

The pilot has reported that on the final leg of a competition cross country flight he was forced to make an outlanding. He reported that he flew a full circuit for the selected landing site and completed his checks on the downwind leg. Shortly before touchdown, the glider encountered some turbulence, and the landing gear warning horn sounded. The pilot suspected that the landing gear was not fully locked down. To check the landing gear, he released the speed brake control from his left hand and transferred that hand to the control column. This allowed him to check the landing gear lever with his right hand. During this transfer of hands, he lost control of the glider which impacted the ground and suffered substantial damage. The landing gear was found to be "in-transit" after the glider came to rest. Subsequent investigation by the gliding club showed that the landing gear lever could be moved in its detent such that the warning horn micro-switch operated while the landing gear was still down and locked. It is possible that when the horn operated during turbulence on the approach the pilot moved the gear lever forward which acted to retract the landing gear. The pilot was relatively inexperienced and suggested that when the warning horn sounded, he was startled and moved the landing gear lever in the direction he became used to while recently training in the IS-28 glider. This was opposite to the movement required in the Hornet.

Significant Factors:

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

1. While at low altitude during an outlanding the pilot was startled when the landing gear warning horn sounded.

2. The landing gear mechanism was not correctly adjusted.

3. The pilot changed hands on the control column so he could move the landing gear lever. During this action he lost control of the glider. This accident was not the subject of an on-scene investigation.

The pilot had landed at the strip on a number of previous occasions, but this was the first time in this aircraft type. To give himself more time the pilot made a longer than normal final approach. At about 100 feet above the ground, with the airspeed at about 65 knots, the aircraft began to sink. The pilot applied full power to commence a go-around and as the nose pitched up, the left wing dropped. The pilot did not prevent the nose of the aircraft pitching up, thus aggravating the almost stalled condition of the aircraft. Power was then reduced and the aircraft landed heavily in a wheat paddock along side the strip and slid sideways as it came to rest.

The pilot reported that as he applied full power for takeoff, on strip 32, the aircraft began to swing to the left. He was unable to correct the situation and the aircraft ran off the strip and collided with trees. The wind velocity at the time was reported by the pilot to have been a light south-westerly. The topography surrounding the strip is known to give rise to sudden and unpredictable wind gusts and it is possible that the aircraft encountered such a gust as the takeoff run was commenced.

The student had completed about seven hours training and was undergoing her second session of circuit training. The instructor stated that the student had previously had difficulty with the directional control of the aircraft. On this takeoff he allowed the student to manipulate only the rudder, so that she could concentrate on the directional control aspect, while he manipulated all the other controls. As the power was increased the aircraft gradually swung to the left. Approaching the left side of the strip the swing increased and the instructor applied right rudder at the same time as the student. The aircraft swung to the right and as it crossed the right side of the strip the left wheel dug into the ground and the aircraft tipped onto the left wing.