Circumstances:

The pilot had been spraying rice fields when the aircraft began to vibrate severely and lose height. He began a turn into wind to position the aircraft for a forced landing in a dry paddock, adjacent to the field under treatment. During the turn the aircraft struck a small earth bank which tore off the main landing gear. The reason for the vibration has not yet been established. However, a piston failure is suspected as pieces of piston and piston ring material were found in the engine sump.

Circumstances:

The pilot intended to land on a small knoll in the centre of a large, cleared area in heavily timbered country. During the flare to land over a large depression, the pilot noticed a lack of power accompanied by the Low Rotor RPM Warning Horn. He lowered the collective control and wound the throttle to maximum in an attempt to regain rotor RPM. In doing so, he oversped the engine and rotor, and subsequently overshot the landing site. He was convinced that he had a genuine power problem and elected to land in a gully beyond the knoll. The tail rotor struck ground in the steeply sloping gully, resulting in the tail boom being cut off by the main rotor. The cabin came to rest on a heap of storm debris. During later investigation, the engine was ground run successfully. A small fuel leak existed at the carburettor, but this did not affect the fuel supply to the engine. The pilot had not received any training in ridge line operations. He had made his approach using visual cues only, which can result in a steep final approach accompanied by a high rate of closure. In addition, the pilot was unaware of the local wind velocity, and the aircraft was probably subject to local airflow effects. While attempting to compensate for these, it is probable that the pilot over-pitched the main rotor blades leading to a temporary reduction in main rotor RPM. He subsequently misread the symptoms as an engine malfunction.

Significant Factors:

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

1. The pilot was inexperienced in ridge line operations.

2. The pilot did not maintain adequate rotor RPM during the latter stages of the approach.

3. The pilot considered that the engine had failed

 4. The aircraft was force landed on unsuitable terrain.

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.

After refuelling, the pilot found one of the tanks contaminated with water. The fuel was drained from the tank and clean fuel added. No contamination was found in the subsequent check of the fuel in the tank. The aircraft was then washed using a high pressure water hose. During the following flight, the engines began to run roughly and the pilot decided to carry out a landing in a paddock. The surface of the paddock was rough and the aircraft bounced heavily and groundlooped, collapsing the right gear. The investigation revealed that water had been present in the fuel system for sometime. Because of the design of the fuel system it is not possible to drain the lowest point of the fuel tank while the aircraft is parked. It is probable that the engine rough running was caused by a combination of contaminated fuel and a sticking valve.

Circumstances:

The pilot reported that he was approaching to land in a clear area when the right skid struck an ant bed. The aircraft rolled and impacted the ground on its right side. The ant bed was partially hidden by long grass.

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.

Circumstances:

The pilot stated that whilst aerial mustering he attempted to push a beast out from under a bush. The beast ran out from under the bush but headed away from the main mob. The pilot was attempting to turn the beast back towards the mob, when his passenger warned him of a power line which was in close proximity to the aircraft. The pilot stated that he flared the aircraft abruptly to try and avoid the power line, but the aircraft then began to sink, and the main rotor struck the power line. The aircraft then struck the ground heavily after falling about 30 feet.

The pilot decided to divert to a nearby aerodrome because the fuel gauges indicated a low fuel quantity remaining. Shortly after commencing the diversion the engine failed. During the ensuing forced landing the aircraft struck a fence post, overturned, and slid inverted for 120 metres. The engine had failed from fuel exhaustion. During the flight, which involved 3 landings, one refuelling and about 6 hours flight time, the pilot had not conducted a check of the aircraft fuel consumption. Although the fuel gauges indicated a higher than normal rate of consumption, the pilot did not land at suitable enroute aerodromes and the diversion was not made until a critical situation had developed. Subsequent examination of the engine and fuel system did not establish the cause of the excessive fuel consumption.

Circumstances:

The helicopter was being used to muster cattle from a paddock to a lane. One animal had stopped, and the pilot manoeuvred the helicopter towards this animal. This required a down-wind hover in gusty wind conditions and a high air temperature. The paddock was open, and the pilot did not consider it was a difficult operation. As the helicopter approached the animal, the pilot realised he had applied full anti-torque pedal and was over-pitching the main rotor. He lowered the collective pitch control, but the tail hit a dead tree, the tail rotor blades separated and then the main rotor blades struck the tree. The helicopter landed heavily, bending the skids. The pilot's acknowledged flying rate was high prior to the accident. This flying was mainly on cattle mustering operations in hot, dusty conditions. Such operational conditions, combined with the flying rate and the concentration and skill required, may have resulted in skill fatigue, which is characterised by insidious lapses in performance and judgement. At the same time, the pilot, considering the final muster to be relatively easy, might have become complacent and failed to give full concentration to the job.

Significant Factors:

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

1. Possible pilot skill fatigue due to a combination of hours flown and difficult operational conditions.

2. Possible complacency due to a perceived easy final muster.

3. The pilot overpitched the main rotor while operating down-wind in hot and gusty conditions.