Loss of control

Circumstances:

Well before the flight was due to depart, the company agent at Mabuiag Island endeavoured to warn the operator that the strip was wet and unsuitable for operations. This attempt to communicate failed due to a local fault in the Telecom system. The pilot was aware of a previous recent accident where a pilot landed short of the runway lip. When he arrived, he assessed the strip as suitable and landed well into the strip. By the time that he discovered that the strip was slippery, it was too late to go around. When it became obvious that he could not stop within the confines of the strip by using normal braking, he attempted a ground loop. The aircraft slid sideways off the end of the strip onto a beach.

Circumstances:

The pilot had purchased the aircraft some time prior to the accident and did not fly it until he had completed a full training course on gyroplanes of some 7-8 hours. Since completing the training, the pilot had flown about ten hours on type, mainly on windmill inspections on the property. The witnesses to the accident reported that the pilot had taken off on a windmill inspection and they had seen him return about 15 minutes later. As they watched from about one kilometre away, they saw the pilot approach the landing area at about 400 feet above ground level and commence a turn. The aircraft was then seen to nose over and continue in a dive until it struck the ground and exploded on impact. The South Australia Rotor Club was co-opted to assist with the investigation and through their assistance it was learned that this type of gyroplane was fitted with a large pilot cabin that extended some two feet in front of the rudder pedals. Other pilots have reported that this fitment induced severe pitch down in flight and/or severe yawing due to the imbalance of the air loads on the cabin compared to the correctional force available from the moments of an unmodified empennage. In effect, the anti-yaw moment from the rudder and fin is insufficient and the aircraft is without an effective horizontal stabiliser for effective anti-pitch control. A reduction of power at the onset of any perceived instability would be instinctive and would also reduce a pilot's ability to control the yaw due to the reduced propeller wash over the rudder and fin. The conclusions drawn from the investigation were that the pilot experienced a pitch down and/or yaw in flight that resulted in the imposition of negative g forces. These forces caused the retreating main rotor blades to dip and strike the fin and rudder. At the same time, the propeller would have disintegrated on contact with the rotor blades as they dipped into its arc. The blade strikes were such as to stop the main rotor and put the aircraft beyond the control of the pilot.

Significant Factors:

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

1. Faulty design. The aircraft was unstable when fitted with a large forward cabin.

2. An uncommanded DEPARTURE from controlled flight caused the main rotor blades to strike the propeller and empennage.

3. The rotor blades were stopped in flight rendering the aircraft uncontrollable.

Recommendations:

1. That the Civil Aviation Authority, in conjunction with the Australian Sports Rotorcraft Association (ASRA), advise all gyroplane operators of the design instability of the Wasp Air Buggy II when fitted with a large cabin.

2. That the CAA, in conjunction with the ASRA, devise and/or approve a suitable modification to the empennage of gyroplanes in conjunction with the fitment of large cabins.

3. That the short period oscillation of gyroplanes operated in Australia be examined. i.e. fit or replace the horizontal tailplane. A number of accidents in Australia can be attributed to DEPARTURE from controlled flight as a result of excessive pitching, (porpoising).

Circumstances:

The pilot reported that he had made a normal landing on the grass runway 14. The wind was a light crosswind from the left. During the ground roll the aircraft began to swing to the left. Application of right rudder was not effective, and the aircraft ground looped to the left. During the ground loop the right hand gear leg broke off and the right wing contacted the ground. At the time of the accident there was a thunderstorm developing nearby and strong thermal activity was reported in the circuit area by another pilot. The loss of directional control was probably caused by a sudden wind gust associated with the unstable local conditions.

Circumstances:

The glider was lined up short of the normal launch point. During the winch launch the wing-walker apparently released the into wind wing early. The wing dropped and the glider veered into the gusting crosswind. The pilot abandoned the launch however the glider continued to weathercock and ran into the retrieval vehicle before being brought to a halt.

The pilot had recently purchased the glider, and had previously made two short flights in it, for endorsement and familiarisation purposes. On the day of the accident he had trailered the glider to the launching strip, and had then assembled and rigged it for flight. A normal winch launch was carried out, with the glider releasing from the winch at about 1000 feet above the ground. It was then observed to be circling in a thermal, while gaining a further 500 feet of altitude. The angle of bank at this time appeared to be moderately steep. A witness then observed that the nose of the glider dropped and the aircraft commenced to spin to the left. It spun rapidly in a steep nosedown attitude, with occasional pitch oscillations, and recovery was not effected prior to impact with the ground. The subsequent investigation did not reveal any apparent faults or defects with the aircraft which might have led to the development of the accident. In addition, there was no medical evidence to indicate that the pilot was incapacitated or unfit to perform his duties as pilot in command. Although the pilot had received training in spin recognition and recovery techniques, he was possibly unaware that a spin could occur during an apparently normal thermalling turn. It could not be established when he had last performed spinning manoeuvres.

Circumstances:

The sea state for take-off was moderate with a 35 centimetre chop. As the aircraft approached 40 knots, it struck a wave and bounced into the air. When the aircraft settled back onto the water it was yawed to the left, and this caused it to slide sideways into another wave. The engine and its support pylon broke off at the fuselage. The aircraft sank shortly after coming to a stop. All occupants evacuated successfully. The pilot reported that the yaw was probably induced when the left hand float entered a wave. He was unable to realign the aircraft before it collided with the second wave. The force of the impact although it did not feel severe, caused the engine and pylon to break off. The rear seat passenger seated on the left hand side, was injured when the sash seat belt anchor point was torn from the aircraft. The sash seat belt upper anchor points are also the anchor point for the engine pod bracing wires. As the engine pod and support collapsed to the right, the left hand bracing wire and anchor block were pulled from the fuselage, tensioning the left sash belt and pulling the passenger's head into the fuselage structure.

Recommendations:

The Bureau conducted an examination of the seat belt anchor point failure.

1. It is recommended that the Manufacturer redesign the seat belt anchor point so that it is separate from the engine pod bracing wire anchor point

The flight was intended to provide familiarisation for the pilot on the aircraft type. After loading water into the hopper the pilot took off and carried out a series of turns before positioning for a spray run along one of the flight strips. At the end of the run the aircraft pulled up steeply and began banking to the right. It then appeared to enter a spin to the right and subsequently struck the ground in a steep nose-down attitude with little forward speed. The pilot had been instructed to load 100 gallons of water for the purpose of this exercise. Unsupervised, the pilot loaded 200 gallons of water which resulted in the aircraft being operated at the maximum all up weight approved agricultural overload. It subsequently stalled in a procedure turn at a height from which the pilot was unable to effect recovery before impact with the ground.

Circumstances:

The pilot had hired the helicopter to fly a friend to his property situated about 2500 feet above sea level. On arrival the pilot landed next to the homestead and removed the passenger door so that his friend could take aerial photographs. The weather was fine, with a 10-knot wind from the north-west, and a temperature of 30 degrees Celsius. The density altitude was 5500 feet. After flying the helicopter around the property boundary, the pilot considered that it may be more advantageous if they climbed higher from where a more panoramic view of the property could be obtained. A climb was made in an easterly direction, at a slow forward speed, to about 500 feet above ground level, at which point the helicopter began to pitch and fishtail from side to side before descending rapidly. This was witnessed by a farmer working nearby, who said that he did not hear any change to the normal sound of the helicopter before it disappeared behind a ridge. The helicopter contacted the tops of the trees at a very slow forward speed and low main rotor RPM. During its descent through the trees to the steeply sloped forest floor the helicopter struck, and broke off, a large branch which entered the cabin resulting in a fatal injury to the pilot. The helicopter came to rest on its side, 19 metres from the initial contact point with the trees. The pilot had only recently qualified for his Private Pilot Licence (Helicopter) and had not received instruction in the methods for conducting helicopter survey or photography operations. There was no evidence that the helicopter was not capable of normal operations prior to the accident. Investigation found that the helicopter, which had been relatively heavy but within limitations, was operating at a high-density altitude and a slow forward speed while climbing in a downwind direction. The subsequent loss of translational lift and true airspeed (TAS), combined with a reduction in engine performance due to the conditions, required the pilot to use considerably more power and collective pitch than normal to commence and maintain the climb. When the helicopter's operation became erratic, the pilot told the passenger they would fly out of the situation and mentioned autorotation. He was observed by the passenger to be making rapid movements of the controls with his hands and feet. The circumstances of the accident were consistent with the pilot probably allowing the main rotor speed to decay due to overpitching of the rotor system, then using large left pedal inputs to prevent the helicopter from turning. The increase of tail rotor pitch further assisted decay of the main rotor speed. The low inertia rotor system used on this type of helicopter makes it susceptible to rapid rotor speed decay, but it can be regained quickly if there is no delay in effecting recovery action. The speed and height of the helicopter placed it in the avoid area of the height-velocity curve, and the action by the pilot of entering an autorotation failed to restore the main rotor RPM. If the helicopter had been allowed to weathercock into wind, then flown away towards the lower cleared terrain, a successful recovery may have been accomplished. As the helicopter descended rapidly towards the trees, the natural reaction of the pilot would have been to pull up on the collective pitch lever in order to arrest the descent, causing a further reduction to the remaining main rotor speed. This was evident by the lack of rotational damage to the main and tail rotor blades, however this action probably reduced the helicopter's vertical descent speed sufficiently to prevent more serious injuries to the passenger. When the rotor speed decreases below 95 percent a warning horn sounds and an amber light illuminates. During the descent, the passenger could not remember hearing a horn blowing but had seen lights flashing on the instrument panel. When the problem commenced, he may not have registered any noises but did notice the warning light. There are several warning lights in the Robinson R22 helicopter, and each associated system was checked and found serviceable. The type of operation, and prevailing weather conditions, would have required the manufacturer's performance criteria to be observed, and a considerable amount of attention given to flying the helicopter.

Significant Factors:

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

1. The helicopter's performance was affected by the hot weather and high-density altitude conditions.

2. The pilot had not received training to perform aerial photography.

3. The pilot climbed the helicopter downwind at a low forward speed.

4. The pilot did not adequately compensate for the prevailing weather conditions, probably due to diverting his attention to photographic considerations.

5. The pilot overpitched the rotor system and then did not effect a successful recovery of the main rotor speed.

Circumstances:

The student helicopter pilot was at an early stage of his training, however, he was a very experienced fixed-wing pilot. Before conducting some circuits, he was given practice in hovering. After this the instructor took over to demonstrate the manoeuvrability of the helicopter with the rotor disc steady. During this hovering the height increased to about 30 feet before the aircraft began to spin rapidly in an anticlockwise direction and dive towards the ground. The low rotor rpm warnings sounded during the descent. Impact evidence showed that the helicopter had struck the ground at a high rate of descent while travelling forward slowly. No signs of engine malfunction were found.

Significant Factors:

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

1. The instructor did not maintain directional control of the aircraft.

2. The instructor did not maintain adequate rotor rpm.

3. The instructor was operating outside the safe flight envelope.

The pilot had been flight checked for solo flying in the morning prior to the accident. On the first solo circuit when on approach to land the pilot realised the glider was lined up too close to several gliders parked in line ahead on the airfield. The approach was made in a light cross wind from the left. The pilot corrected in the wrong direction for the misalignment, compounding the problem. As the airbrakes had not been deployed the glider was unable to be landed beyond the parked gliders. After touchdown, despite an attempt to avoid the raised right wing of the closest glider,the left wing of the landing glider struck the right wing tip of the parked glider, swinging the landing glider toward the next aircraft in line. The left wing of the landing glider struck the right wing of this second glider, resulting in substantial damage to both aircraft. This accident was not the subject of an on-site investigation.