Loss of control

The pilot was attempting a 300km cross country flight. After release from the aerotow the glider only achieved 3000 feet above mean sea level. As the flight continued no further height gain was achieved and on descending to below 2000 feet the pilot decided to carry out an outlanding. While the glider was being manoeuvred in the circuit, at about 50 feet above ground level, the right wing dropped and struck the ground. The pilot had selected a landing field when flying with 2000 feet indicated on the altimeter. He was unaware that the terrain over which he was flying was 1000 feet above mean sea level and thus only 1000 feet below the aircraft. During the approach the aircraft became low and the airspeed decreased until the aircraft stalled at too low an altitude to allow recovery.

The pilot approached the helipad flying into a 15 knot wind. He overflew the pad and turned left through 180 degrees and overflew the pad again. The helicopter was then slowed to about zero knots IAS and placed in a tight left turn with the intention of approaching the helipad for a landing into wind. After the turn onto downwind was completed translational lift was lost when the pilot reduced airspeed to close to zero knots. The tight left turn was then initiated. The combination of the loss of translational lift and the turn probably required more power from the helicopter than it was capable of delivering. The rotor R.P.M. decayed significantly as the helicopter was overpitched and a high sink rate developed. A passenger, who was a more experienced pilot, took control and attempted to recover rotor RPM but he was unsuccessful. The helicopter impacted heavily with the ground and a pile of gravel and rolled onto its right side.

The pilot had been engaged in glider towing operations for about four months, and had completed 108 towing flights. During the afternoon the pilot had carried out two aerotow flights without incident. On the accident flight a normal take-off and transit to the north side of Korumburra township was made. The glider was released at a height of 2000 feet above ground level and the tug aircraft then turned and tracked towards a right base leg position for the south west landing strip at Leongatha. Not all of this flight was observed, but two witnesses noticed the aircraft descending in a spin to the right. It appeared to recover briefly, with the nose being raised above the level flight attitude, however a spin to the left then commenced. This spin continued until the aircraft disappeared from sight, but the wreckage distribution and impact marks indicated that the pilot had been able to stop the rotation in the last moments of the flight. It was evident that insufficient height remained to effect a full recovery. A detailed inspection of the wreckage did not disclose any defect or malfunction with the aircraft, its engine or systems that might have contributed to the development of the accident. It was considered unlikely that the pilot had deliberately entered a spin on his return to the airfield. The aircraft type is not approved for spinning, and the spin characteristics of this particular two seat conversion are unknown. There was no evidence available to determine how or why the spin situation developed. It was apparent that the pilot had succeeded in partially recovering from the initial spin, however the recovery technique being employed did not prevent a spin in the opposite direction.

The aircraft was taxied in the early dawn light with an overcast sky and drizzle. The aerodrome pilot-activated lights were not on nor were the aircraft landing and taxi lights. The aircraft was inadvertently taxied off the taxiway. During attempts to return to the taxiway the nose-wheel of the aircraft entered soft ground and was broken off.

Prior to flying the club's single seat glider, the visiting pilot was required to undergo a dual check. His first check flight was conducted in VH-IKB by the club's Chief Flying Instructor who was not satisfied and required another flight. The second take-off appeared to be normal but after lift off the glider entered an uncontrolled climb. The pilot operated the cable release and handed over control to the instructor There was no elevator control available and the glider climbed to about 200 feet above ground level where it stalled and turned left through about 90 degrees. The glider descended steeply and impacted the ground on the left wingtip followed by the nose and right wingtip. It came to rest after sliding about 20 metres. After the accident it was found that the cast-alloy elevator horn had failed as the result of a single overload. Examination of the casting revealed widespread and excessive porosity resulting in a degradation of the material static strength including its resistance to impulsively applied loads. The investigation established that, during the previous landing, the glider had touched down heavily and there was a "sharp" impact in the tail area. Prior to the accident flight, the tail of the glider was visually inspected but no evidence was found of any damage. It was not possible to determine positively if the casting failed during the accident or on the previous landing.

The purpose of the flight was to show the passenger the characteristics of a tailwheel aircraft. After a normal approach and touchdown the aircraft was observed to go-around and fly level at a low height above the runway. The aircraft was then seen to climb steeply, stall, and to impact the ground in a steep nose down attitude whilst rotating to the right. No fault was found with the aircraft that could have contributed to the accident. The pilot was inexperienced on the aircraft type and did not maintain adequate flying speed when manoeuvring the aircraft after take-off.

Circumstances:

The pilot reported that the helicopter was descending through 200 feet on approach to land in a clear area surrounded by trees 15-20 metres tall. Airspeed was 15-20 knots, engine power setting was about 15 inches Manifold Pressure, and the approach was being flown into a north-westerly wind of 5-10 knots. Without warning, as a result of what the pilot thought was a sudden wind change, the helicopter yawed slightly right and began to sink rapidly. The pilot noticed that the airspeed was indicating zero. The pilot managed to avoid the trees but could not prevent the helicopter landing heavily, damaging the main rotor blades and gearbox.

The pilot reported that the take-off on runway 17 proceeded normally until immediately after the gear was selected up. At this point the aircraft pitched up and rolled to the left. The pilot pushed the auto-pilot release button on the control column and heard the release annunciator sound, however he noted that the yaw damper and auto-pilot annunciators were illuminated. He also noted the elevator trim wheel moving and shortly thereafter the stick shaker began to operate at an aircraft speed of about 115 knots. The aircraft was manoeuvred for a successful landing on runway 26. It was determined that water had entered the auto-pilot computer via a faulty seal on the electronics compartment door. Prior to take-off the pilot armed the flight director system in the indicated air speed and heading modes. During the take-off run the auto-pilot engaged, wound the elevator trim nose up and commanded a left turn. The pilot managed to overpower the auto-pilot inputs by applying extremely high forces to the control column, but in doing so was unable to withdraw one hand from this task to trip the circuit breaker controlling power to the auto-pilot.

The pilot lived alone on his property and was last seen on 29 April when he indicated to a friend that he planned to fly his aircraft the following day if conditions were suitable. He had not flown the aircraft before, but was believed to have made taxy runs and short hops during the previous weeks. Two days later the pilot's brother reported that he was missing and that the aircraft was not at the property. The wreckage was located the following afternoon by a search aircraft. An inspection of the wreckage indicated that the aircraft had struck the ground inverted, at a low forward speed, and that the engine was not developing power at the time of impact. No fault was subsequently found with the engine, and it was considered that it had probably stopped shortly before impact, under negative "g" conditions. The pilot was inexperienced, and the particular aircraft was known to be difficult to control in pitch. It was likely that the pilot experienced handling problems which he was unable to correct before the final loss of control.

Circumstances:

The aircraft had a recent history of directional control problems while operating on water. On two earlier flights on the day of the accident, while landing in strong wind conditions, the aircraft had slewed sharply left when the left pontoon contacted the water. The final landing took place in light wind conditions. On this occasion, as the left pontoon entered the water, the nose of the aircraft dipped, and the aircraft flipped over. Due to accident damage, it was not possible to make an accurate determination as to the cause of the control problem. However, repair work had recently been carried out on the aircraft after it struck a submerged object while landing.

Significant Factors:

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

1. The pilot attempted a landing on water knowing that the aircraft had a directional control problem.

2. The pilot lost directional control of the aircraft on landing.