Loss of control

The aircraft departed the airfield in calm conditions and flew to a point about 35 kilometres to the south-east. On his return the pilot positioned the aircraft to land on runway 09. The aircraft was struck by a strong wind gust which lifted the right wing and caused the aircraft to veer to the left. The pilot was unable to regain directional control before the aircraft collided with a boundary fence. The wind was reported to be variable in direction at five to ten knots. This accident was not the subject of a formal on-scene investigation.

After travelling 15 metres during a winch-launch the left wing-tip contacted the ground. The instructor immediately assumed control of the glider and applied right rudder and aileron but the left wing entered an oat crop on the edge of the strip. The tip then dug into soft soil, causing the glider to cartwheel and impact heavily on its nose 120 metres from the take-off position and 35 metres to the left of the centreline. The crop on the edge of the 15 metre wide strip was about 1 metre high and the glider's wing span was 17.5 metres. The student was experiencing difficulty learning to control the aircraft during take-off and following wing-tip contact with the ground both the instructor and the student stated that they made control inputs. Conditions during the day were hot and the instructor had been on duty for nearly ten and half hours.

The aircraft was being used to transport equipment for members of an Aero Club, who were to carry out training at Goulburn. As the pilot was undergoing formation flying training, it was decided that he would lead a formation of two aircraft for the flight. A briefing on the procedures to be followed was carried out. During the flight the pilot of the second aircraft began to suspect the accuracy of his aircraft's airspeed indicator and requested that it be checked against that of the lead aircraft as the aircraft joined the circuit. The pilot of the lead aircraft extended the landing gear and flew the initial leg of the circuit at an indicated airspeed of 96 knots. At the end of this leg the pilot turned the aircraft steeply to the left, the nose dropped slightly and the aircraft flicked into a steep right turn. The aircraft then assumed a steep nose down attitude, however, the pilot was able to level the wings and raise the nose to the level attitude before impact. The impact occurred at a very high rate of sink. The pilot had not previously practiced steep turns at relatively slow airspeed and was not aware of the stalling speed in the given configuration and attitude. The pilot was subsequently unable to recall the reason for attempting a steeper than normal turn. When the aircraft stalled the pilot was unable to effect a full recovery in the height available before impact with the ground.

Circumstances:

The pilot was attempting an aerotow take-off from a stubble covered paddock following an out-landing. During the ground roll, directional control was lost and the take-off discontinued after the wing tips contacted patches of stubble. The rear fuselage fractured during an ensuing ground loop.

Circumstances:

The pilot was operating into a modified platform located in mountainous terrain and built on a steep slope. He had landed there about ten times in the previous forty eight hours, in support of a geological survey team. The weather at the time was fine, with occasional gusts of wind. The pilot held the helicopter skids lightly on the platform, parallel to the heavy loose planks making up the platform, and side on to the slope. It was estimated that the tips of the main rotor blades were about 1.5 metres vertically clear of the slope, with the cyclic control in the neutral position and the rotors at normal operating rpm. One man was present in the rear cabin to receive trays of core samples from four others who carried the trays to the helicopter. The pilot was unable to remember exactly what happened, but the man receiving the core trays into the cabin clearly remembers a very strong wind gust which caused the tail of the helicopter to suddenly swing towards the slope. He was also aware of the cabin moving slightly towards the slope because a core tray suddenly became harder to reach. He was also aware of the left side of the helicopter suddenly lifting slightly prior to massive vibrations consistent with rotor strikes. The main rotor blades clipped the tops of small stumps before striking the ground forward of the stumps. The rotor strikes were so severe that the main rotor and gearbox assembly were torn out of the helicopter and flung 10 metres down the slope. Sudden stoppage forces shattered the engine reduction gearbox and the free turbine, parts of which penetrated the rear luggage compartment. The rear of the engine caught fire briefly. Injuries sustained by ground personnel occurred as they ran for cover. The helicopter remained upright on the platform. The site did not meet the approved helicopter landing site standards prescribed by the Civil Aviation Authority.

Significant Factors:

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

1. The helicopter landing site contained obstructions likely to interfere with the manoeuvring of the helicopter.

2. The helicopter was affected by a strong gust of wind.

3. The pilot was unable to prevent the rotor blades striking obstructions at the site.

4. It is highly probable that the right side skid settled between the insecure planks of the platform.

On arrival in the circuit at the destination, the pilot estimated the wind strength at 5 to 15 knots blowing directly across the strip. He elected to land towards the north east with the crosswind from the left. After landing the pilot reported the aircraft was hit by a wind gust which tipped it onto its right wing. The aircraft then weather cocked and ran off the mown section of the strip into long grass where it overturned. This accident was not the subject on an on scene investigation.

At the conclusion of a property inspection the pilot decided to practice a glide approach in 15 knot wind conditions, which gave a light crosswind on the selected strip. Initial touchdown was on the tailwheel and the aircraft bounced. After the next touchdown the aircraft commenced to run off the side of the strip. The pilot applied power to go-around but the propeller struck the ground and the aircraft came to rest on its nose in a paddock adjacent to the strip. When the aircraft bounced, the pilot had not maintained the control inputs required to compensate for the crosswind, and after the subsequent touchdown the aircraft had commenced to weather-cock. Having applied power to go-around, the pilot had progressively pushed forward on the control stick, in the belief that the tailwheel was still on the ground.

The aircraft was to operate a passenger carrying flight to Townsville. Witness reports indicate that the aircraft was aligned on runway 14 in preparation for takeoff. Power was applied and the takeoff run commenced. At the beginning of the takeoff run the aircraft veered to the right and the right mainwheel ran off the sealed runway onto the grass. The aircraft then veered sharply to the left, crossed the runway and ran onto the grass beyond the gable markers. The aircraft then collided with a concrete culvert, crossed a roadway, and came to rest in trees 315 metres from the runway threshold. Comprehensive examination of the aircraft did not reveal any defect or failure that may have contributed to the development of the accident. The weather at the time of the accident was not contributory. The flight crew declined to make themselves available to the investigators for interview. The crew were issued with summonses but did not answer the summons, apparently under direction from their industrial association. This action by the crew hampered the investigation and resulted in no causal factors being determined.

Circumstances:

The pilot was flying a right hand circuit for Runway 35 at a height of about 500 feet above ground level. The aircraft was observed at a base turn position to suddenly bank about 30 degrees to the right, and then to adopt a nose low attitude and begin rotating to the right. This rotation continued until the aircraft struck the ground. No fault was subsequently found with the aircraft which might have contributed to the accident. The pilot reported that he had reduced engine power on the downwind leg because the aircraft speed was too high. He recalled that after the aircraft began rotating, he had pulled the control column backwards, in an attempt to raise the nose of the aircraft and recover to normal flight, but this had no effect. The behaviour of the aircraft immediately prior to impact was consistent with its speed decreasing to the point where the wing(s) stalled and the aircraft entered a spin to the right. The pilot had completed an aerobatic endorsement (including spin entry and recovery) on the aircraft type some five months before the accident. However, he reportedly had only four opportunities to practice spin recovery since then. The attempt by the pilot to recover from the spin by moving the control stick backwards was incorrect and was probably a spontaneous action on his part triggered by the sudden onset of the spin and the low height above ground level at which it occurred.

Significant Factors:

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

1. The pilot did not maintain sufficient airspeed for the conditions involved.

2. The aircraft stalled and entered a spin to the right.

3. In what was probably a spontaneous action on his part, the pilot applied an incorrect technique in attempting to recover from the spin.

Recommendations:

Examination of the cockpit areas of the aircraft showed that the left hand shoulder harness attachment point for the front seat safety harness had failed, possibly contributing to the injuries received by the passenger. The shoulder harness arrangement is that the shoulder straps are attached to a common end fitting which is equipped with a pulley. The pulley is free to move laterally on a traverse cable which is attached via lugs bolted to the left and right upper fuselage longerons. In this case, the lug on the left side had separated from its longeron when the rear of the two attaching bolts failed. The failed bolt was not recovered but probably failed due to a combination of tension, bending and shear loads. The recommendation is made that the Civil Aviation Authority consider requiring either modification of the lug to prevent deformation of its rear end, or replacement of the rear bolt with a larger diameter bolt to prevent local bending of the bolt.

The pilot reported that he intended to carry out a touch and go landing. The approach was normal but after touchdown, the aircraft started to drift to the left. The pilot advised that because of his familiarity with hang glider operations, he used the wrong rudder in an attempt to correct the situation. The nose swung rapidly to the left and the nose gear collapsed. The aircraft came to rest at the edge of the runway.