Loss of control

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.

Circumstances:

A ground witness heard the aircraft's engine power increase and observed the aircraft pull up, roll over and enter a spin to the right. He estimated the aircraft was about 3000 feet above the ground. The aircraft spun six to eight turns to the right and at about 600 feet above ground level the right spin ceased before the aircraft entered a spin to the left. The left spin stopped after about one turn and the aircraft appeared to be recovering from the dive when it hit the ground in a wings level, 45 degrees nose down attitude. The pilot-in-command, who occupied the rear seat, held a low-level aerobatic approval to operate down to 1000 feet above ground level. He had often spun the aircraft but is reported to have normally recovered after two turns. The other pilot who occupied the front seat, held an aerobatic endorsement but this was his first flight in a Zlin. It is not known which of the pilots was at the controls when the aircraft entered the right spin, however, the aircraft was normally commanded from the front cockpit. Injuries sustained by the pilot-in-command indicate that he was at the controls at the moment of ground impact. The normal technique prior to the entry of an intentional spin in the Zlin is to reduce power to idle. Considering the report that engine power was increased prior to the spin, it is possible that the spin entry was unintentional. It is the recommended practice in the Zlin to recover from a spin after two to three turns. Why the pilot(s) failed to recover from the right spin after two to three turns could not be determined. An examination of the wreckage and associated aircraft documentation did not reveal any fault that may have contributed to the accident. The prevailing weather was not considered a factor.

Significant Factors:

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

1. Entry to the right spin was possibly unintentional.

2. The pilot at the controls probably experienced some difficulty recovering from the initial spin to the right.

3. Recovery from the right spin was inadequately executed and the aircraft entered a spin to the left.

4. There was insufficient height for the aircraft to recover from the left spin.

The Private Pilot Licence holder was undergoing type endorsement training. During the third landing, on runway 29 Left, the aircraft commenced to swing to the right. The pilot in command reported that after checking that there were no obstructions he allowed the swing to continue. The student pilot was unable to stop the swing and as the aircraft turned through 40 degrees it began to skid, with the result that the landing gear folded. The aircraft is fitted with a tailskid but no brakes, and was unable to use the normal unsealed landing area as that area was wet and out of service. At the time of the landing the wind conditions resulted in a quartering tailwind from the right at five knots.

The pilot had purchased the aircraft some 12 months previously but had carried out only limited and infrequent training. This training had not progressed to the stage where turns were performed, and was limited to straight and level hops along the strip. On the morning of the accident the pilot had performed several hops, taking off and landing into a light easterly breeze. On about the fifth flight the aircraft climbed to a height of about 85 feet, levelled off momentarily and then descended with reduced power as if for a normal landing. When the aircraft was about 50 feet above the ground and close to the end of the landing area, power was applied, a climb was made to about 200 feet and turns were made to position the aircraft on a downwind leg. Witnesses noted that the aircraft was under control until it suddenly adopted a nose-high attitude, followed by a rapid pitch-down which continued into a tumbling motion. Two in-flight impact noises were heard above the sound of the engine and shortly afterwards the aircraft struck the ground in a steep nose-down attitude while cartwheeling to the left. Wreckage examination showed that there had been two strikes on the tail fin and rudder by the rotor blades, causing the rudder to become detached from the aircraft in flight. It was considered that the pilot endeavoured to carry out a circuit of the strip after he perceived that there was insufficient distance remaining to safely land the aircraft. The reason for the sharp change of attitude on the downwind leg could not be positively established, but was probably due either to turbulence or an incorrect control input by the pilot. When the nose pitched down, the airflow through the rotor disc would have been significantly reduced. This would have led to a loss of rotor RPM and a consequent loss of performance of the rotor to the stage where control of the aircraft could not be regained.

According to his log book, the pilot had flown the aircraft on two previous occasions of about 15 minutes duration each. The pilot was briefed by the owner of the aircraft on power settings and speeds. He then took-off into the south from the strip which is aligned approximately north-south. There was a light southerly breeze blowing at the time. The aircraft was seen to make one right-hand circuit, but it could not be determined if the aircraft actually made a landing from that circuit. When the aircraft was on final approach from a second right-hand circuit at an estimated altitude of about 200-300 feet, it entered a turn to the right. As the turn progressed onto a northerly (downwind) heading, the angle of bank became progressively steeper until it was about 90 degrees. The nose then dropped and the aircraft dived to the ground. The first persons on the accident scene experienced difficulty in removing the pilot's motor cycle type safety helmet (with full face enclosure) before resuscitation could be applied. The investigation did not reveal any pre-existing defects that may have caused the accident. Other pilots reported some turbulence and windshear in the area where the accident occurred. The area was inspected by an officer from the Bureau of Meteorology who specialised in micro-meteorology. His opinion was that turbulence or windshear effects at the time of the accident would have been minimal. The pilot had been receiving dual flight instruction from an ultralight flying school. After a dual instructional flight on the morning of the accident, he had been strongly advised by his instructor not to fly solo until he had completed more dual instruction as the instructor believed that the pilot was not sufficiently competent to fly solo. The pilot lost control of the aircraft for reasons which were not determined.

The pilot was performing a take-off in crosswind conditions of about 15 knots. When the aircraft had reached a speed of about 40 knots it suddenly veered to the left, and despite corrective action the pilot was unable to maintain directional control. With full power still applied, the aircraft ran off the side of the strip. It then passed over an embankment, and travelled a further 200 metres before colliding with trees which were some 60 metres from the edge of the strip. The initial loss of directional control was associated with a wind gust in excess of the maximum for the capabilities of the aircraft. The pilot had persisted with the take-off attempt after the aircraft ran off the strip, because he considered that to have reduced power would have caused the aircraft to ground loop. He had endeavoured to dump the load, but had initially inadvertently applied the spray handle. As a result, only about 10 of the load had been dumped before the collision with the trees.