Loss of control

On 24 October 1989, the student pilot damaged the nose gear of a similar aircraft when he ground looped during a crosswind landing after returning from his first solo flight to the training area. Subsequently he did two dual training flights with different instructors, each flight involving upper air work in the training area and a single landing on return to Bankstown. The student was not given any specific crosswind circuit training, but was authorised for another solo training area flight. During the takeoff run, with an eight knot left crosswind component, the aircraft started to drift to the left of the runway centreline. The pilot applied back pressure to the control column and at this point the aircraft veered further left. As the aircraft ran off the side of the runway, the pilot closed the mixture and throttle and applied brakes. Before coming to a complete stop, the aircraft struck a taxiway sign post damaging the leading edge at the wing root.

The pilot was attempting to land on a 500 metre one-way agricultural strip affected by a gusting downwind component of about 10 knots. The strip was bordered by tall trees and had an uphill gradient of about 5 percent in the landing direction. The strip surface was covered by short wet grass. On short final approach the pilot realised the downwind component was excessive for the strip length available but was unable to go around due to tall trees. He landed the aircraft but was forced to initiate a ground loop to avoid overruning the strip end.

The aircraft was being flown by the owner who had obtained a restricted private pilot licence several hours prior to the accident, and had just completed an endorsement on the type. The front seat passenger was a licenced pilot with slightly more flying experience than the owner. During the landing, the aircraft touched down on one wheel, bounced and yawed to the left. The pilot commenced a go-around but the passenger took control of the aircraft from him. During the attempted go-around, the aircraft was observed to touch the ground again, before flying in a steeply nose high attitude over a parked aircraft and a building. As the aircraft passed over the building a wing dropped and the aircraft subsequently struck a fence post damaging the right stabilator. It became airborne again in a steeply nose high attitude before stall- mushing into the ground, impacting heavily approximately 600 metres from the initial point of touchdown.

The pilot had flown the aircraft to Cockburn Sound to practice circuits. However, after the first landing he found the water conditions too rough to complete a takeoff. The pilot waited for a period in the hope that conditions would improve. Three quarters of an hour later he taxied along Cockburn Sound looking for an area that was suitable for takeoff, but this search was unsuccessful. After beaching the aircraft a second time the pilot observed that the aircraft was taking water. When the pilot attempted to drain the excess water from the bilges he found that the rear bilge pump was unserviceable, and the water had to be drained manually by removing two bungs. The bungs were replaced when the water flow reduced to a trickle after five to ten minutes. The sea state abated after four hours and the pilot decided to carry out a high-speed taxy run during which, if he assessed the conditions were suitable, he could convert the run to a takeoff. The pilot was able to get the aircraft up on to the hull step, however, before he could continue with the takeoff the aircraft suddenly pitched nose-up and then down before nosing over inverted approximately 50 metres from the shore line. Neither occupant was wearing a life jacket although they were carried in the aircraft. Both occupants received injuries which may have required the jackets for survival had assistance not been given from the shore. A screw was found to be missing from a normally watertight panel on the rear fuselage. The screw had been missing since the aircraft was last painted. Tests indicated that water was able to leak into the aircraft via the missing screw hole. Water in the rear fuselage would normally be pumped out by the rear bilge pump, however, it was unserviceable. The pump's impeller had become detached from the drive shaft sometime prior to the accident flight. Tests on the manual draining system used by the pilot indicated that a minimum of 31 litres of water remained in the aft fuselage after draining was apparently complete, when the flow of water had slowed to a trickle. Although the sea state appeared to improve there was still a significant swell running at the time of the accident. The pilot attempted his high- speed run in the direction of the swell instead of parallel to it. It is probable that the combination of an aft centre of gravity, movement of weight associated with the water in the fuselage and the uplift provided by the swell caused the loss of control.

The pilot was conducting a freight charter flight, and witness evidence confirmed that on DEPARTURE he was occupying the left-hand seat. The pilot was accompanied by a friend who was also a commercial pilot, but not endorsed on this type of aircraft. Approximately 18 minutes prior to the estimated time of arrival at the destination, the pilot reported leaving the cruising altitude of 6500 feet on descent. Several minutes after the descent report had been made, a witness about 50 kilometres from the destination reported seeing the aircraft pull-up into a very steep climb from an extremely low height with its wings level, and then become inverted. It then entered what was described by the witness as a spin or spiral dive, before impacting the ground in a near vertical descent. The pilot was found in the right-hand seat, and the passenger had been thrown clear of the wreckage. It was established that neither seat belt had been fastened at the time of the impact. Although it could not be determined which pilot was flying the aircraft at the time of the pull-up, medical evidence suggested that the pilot occupying the right-hand seat position was handling the controls at the time of ground impact. The weather at the time of the accident was fine and clear, with 10-15 knot winds. A thorough examination of the aircraft wreckage did not reveal any malfunction or mechanical failure which may have caused a sudden and severe loss of control. Investigation showed that at the moment of impact the aircraft was in a near vertical descent, without any rotation about the vertical axis, and the wings were in a stalled condition. No reason was found which could have explained either the low flying, or the steep pull-up. During the investigation it was established that with this aircraft type, a considerable degree of sustained elevator force would need to be applied by a pilot in order to achieve the type of flight path reported by the witness. It is considered that such a control input would need to be deliberately executed.

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.