The aircraft was being flown to Waikerie for a major inspection. While the aircraft was cruising at 2500 feet enroute, the pilot stated that he smelt smoke and almost immediately noticed oil streaming over the windscreen. He closed the throttle and commenced an approach to a large paddock. The aircraft was landed without further damage. The pilot vacated the aircraft via the rear door to avoid the billowing smoke from the engine compartment and attempted to extinguish the fire with a portable fire extinguisher. On realising the attempt would be unsuccessful, he collected his luggage from the cabin of the aircraft and cleared the area. The aircraft was subsequently destroyed by fire. Inspection of the rear of the engine compartment was hampered by the degree of damage caused by the intensity of the fire. The investigation did not discover any malfunction that might have caused the fire.

An exercise in emergency procedures was being carried out in the circuit area. A number of landings were completed, with the instructor simulating a jammed tail rotor pedal. On the last landing, a jammed right pedal was being simulated. After a standard approach for the circumstances, the student flared at about 45 centimetres above the ground and at a speed of about 15 knots. As he then began to reduce power, the engine apparently suffered a substantial loss of power and the aircraft landed heavily. The left landing skid dug in, and the helicopter somersaulted before coming to rest on its right side. No fault or defect was subsequently found with the engine or its systems which might have explained the reported power loss. Atmospheric conditions at the time of the accident were conducive to the formation of carburettor icing, particularly during descents with reduced power. The pilots had not used carburettor heat during the approach, possibly because the carburettor air temperature gauge was indicating a temperature just above the caution range. This instrument was later found to be reading in error by 9 degrees. The pilots had not checked the reading of the gauge against the ambient temperature prior to engine start, and were therefore unaware of the malfunction. When the power loss occurred, the helicopter was in such a position that it had contacted the ground before the instructor could initiate any corrective action.

Shortly after touchdown the nosewheel struck a 20 centimetre high anthill. The downlock latch on the nosegear was broken and when the nosewheel entered a slight depression, some 145 metres further along the ground roll, the nosegear collapsed. The pilot had overflown the strip during the approach. However, due to the height of the grass on the strip the anthill would have been difficult to sight from the air.

Near the end of the landing roll the left wing rose and the aircraft lifted off the strip, then settled back onto the ground on the right mainwheel. The brakes were still applied and the aircraft turned sharply to the right and the right wing struck the ground. The aircraft rolled over and came to rest inverted. The pilot had assessed the crosswind component affecting the main property strip as being close to the maximum for the aircraft type. He had therefore decided to use an adjacent area, which was aligned into wind, but because of the position of buildings at the end of the area a go-around was not possible. It is possible that mechanical turbulence from the buildings effected the aircraft during the landing roll. The approach was conducted at a higher airspeed than that recommended in the P charts, and heavy braking was applied on touchdown before the tailwheel had contacted the ground.

The pilot reported that the helicopter was being hovered above trees when he felt a kick accompanied by a loss of power. He began to manoeuvre towards a clear area but had to pull up to avoid tree tops. The engine surged again and the rotor RPM began to decay. By the time the helicopter was over the clearing the "ROTOR LOW RPM" warning horn was sounding. Shortly afterwards, the helicopter struck the ground heavily in a level attitude. No fault was found with the helicopter which might have explained the reported power loss. However, the aircraft had been transported a considerable distance over rough terrain before it was examined. This could have allowed possible causal evidence to be disturbed.

The pilot had only limited experience on the aircraft type. He reported that when he commenced the final approach, the aircraft was positioned above the normal approach profile with a higher than normal airspeed. The correct airspeed and approach profile was regained but the pilot was slow with the use of power to correct the rate of descent. The aircraft subsequently landed heavily on the mainwheels and when the nosewheel contacted the runway the nosegear leg failed. This accident was not the subject of an on-scene investigation.

The pilot was carrying out aerial observation within the boundary of the property when the engine failed and the aircraft crashed into thick scrub. The engine failure is believed to have been caused by an electrical malfunction. This accident was not the subject of an on-scene investigation.

Circumstances:

During a practice low level circuit, the engine failed, accompanied by a loud bang. During the subsequent forced landing, the helicopter rolled on to its right side. Later examination of the engine revealed that the number three connecting rod had failed at the crankshaft and pierced the crankcase. The connecting rod showed signs of metal fatigue. However, no manufacturing defects were identified near the fracture surface nor was any assembly-related fault established. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. Engine failure as a result of a broken connecting rod.

2. The connecting rod failed from metal fatigue for reasons which were not determined.

Circumstances:

The aircraft was engaged in aerial mustering operations approximately 6 km north-west of Napier Downs homestead when the engine suddenly lost power. At that time, the aircraft was approximately 150 feet above ground level and heading south at 50 knots. The pilot immediately commenced a descent through treetops into a small clearing. Just prior to touching down the aircraft was turned through approximately 90 degrees to face into the light easterly wind to avoid overshooting. The pilot stated that the landing was firm, but not heavy. However, the tail boom was severed by the main rotor blades and carried anticlockwise until it struck the main rotor mast head and the roof of the cockpit bubble. It is possible that the tree strikes on the approach may have damaged the tail boom and the firm landing caused the main rotor blades to strike the damaged tail. Subsequent investigation revealed that the fuel shut off valve was not fully open, although it appeared to be. The fault in the fuel shut off valve was due to excessive wear of the ball valve. It was also revealed that the inlet valve for the number two cylinder was bent. Either or both of these defects could account for the loss of engine power. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. Defective fuel shut off valve.

2. Defective engine inlet valve.

3. Loss of engine power probably related to

1. and/or

2. above.

4. Forced landing in unsuitable area.

The pilot was carrying out aerobatic manoeuvres at 1500 feet over the sea near Rottnest Island. As the aircraft approached the top of a stall turn, under zero gravity conditions, the engine stalled and the propeller stopped. The engine was not fitted with an electric starter motor and there was insufficient altitude available to complete a windmill start. The pilot carried out a successful forced landing in the sea. Subsequent inspection revealed that the engine driven fuel pump had either failed, or was unable to produce sufficient fuel flow to sustain engine r.p.m, due to a split in the rubber diaphragm in the pump. It is probable that loss of fuel pump pressure combined with the the zero gravity conditions at the top of the stall turn caused fuel starvation which resulted in engine failure.