Loss of control

The pilot was conducting a navigational exercise from Benalla to Benalla via overhead Tocumwal N.S.W. The wind conditions were northerly and gusting. The pilot realised he would be unable to effect a return and decided to outland. A paddock was chosen which appeared suitable and provided a good landing run into wind. However the paddock had been ploughed and grass had grown to 0.3 metres high. Following touchdown well into the field the combination of rough ground medium high grass and heavy braking caused the glider to ground loop breaking the rear fuselage as it did so. This accident was not the subject of an on-site investigation.

The helicopter had been transported by road to Schofields to form part of the static display associated with an air show. Although it was airworthy, the helicopter was the only one of its type in the country and had not been approved for flight at the show. At the conclusion of the show, one of the persons responsible for the restoration of the aircraft became concerned for its security, and he elected to hover taxy the helicopter a short distance onto Naval property. He had never received any formal helicopter flying instruction and control of the aircraft was lost shortly after it became airborne. The helicopter struck the ground while moving backwards and came to rest on its side some 60 metres from the parked position.

The particular aircraft is a glider fitted with a retractable engine. Shortly after takeoff for a soaring flight, the pilot noticed that the airspeed indicator (ASI) appeared to be operating erratically. The flight was continued with the pilot estimating the airspeed, but no thermals were found and the pilot decided to return to the departure point using engine power. The aircraft stalled during the landing flare and the left wing struck the ground. The aircraft slewed to the left and touched down while travelling sideways. The fuselage was fractured during the ensuing ground slide. The approach was flown with landing flap and a substantial degree of air-brake deployed. With the engine also extended the glider was in an extremely high drag situation. Although the flight manual is specific about the degradation in performance of the glider with the engine extended, the pilot reported that his endorsement training failed to adequately address this aspect. Investigation also revealed that some dirt and insects were present in the pitot/static plumbing connected to the ASI. These may have caused the reported erratic readings during the initial stages of the flight.

Circumstances:

The occasion of the flight was a photographic shoot to illustrate a pilot's perspective while spinning an aircraft. The pilot had recently completed a course on aerobatics and spinning. At 6000 feet he commenced the entry to a left spin, using the technique taught by the school. After about one and three quarter turns, when the spin appeared 'unusual', he decided to recover, releasing the control column and applying full right rudder. He then noticed the airspeed increasing at an alarming rate but was unable to stop the rotation. The airspeed rapidly increased through maximum permitted airspeed to 180/190 kts, at which point the pilot centralised the controls. The aircraft stopped rotating and the pilot recovered from the dive at about 700 ft agl. He then noticed severe overstress wrinkling on both wings and elected to carry out an immediate power-off emergency landing. The aircraft suffered further damage when it struck a small embankment during the landing roll. The wing damage indicated a rolling overstress consistent with a high speed spiral dive to the right. After analysis and experimentation, the pilot's chief flying instructor was able to reproduce the symptoms and concluded that control relaxation at a critical time in the spin entry resulted in a reversal of direction from a 'left spin' to a very steep and rapid spiral dive to the right. Due to the nature of the rotation, the pilot had not been able to identify the direction.

Circumstances:

An approaching front was causing the wind to swing from a 45 degree headwind/crosswind to a 45 degree tailwind/crosswind from the left. Although the pilot reported that he considered that the conditions were not suitable, he decided to attempt a take-off as he felt there was a pressing need to carry out a survey of his property. Just prior to lift off, the aircraft veered to the left and the nosewheel entered a soft area at the side of the strip. The nosewheel broke off and the aircraft cartwheeled across the paddock. The pilot had completed a rotorcraft pilot's course, consisting of 10 hours of instruction, and the first 10 hours of post course consolidation. However, the pilot had very little experience at operating a rotorcraft in fluctuating crosswind conditions. The loss of control was probably the result of a sudden wind change during the latter part of the take-off roll and pilot inexperience.

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.