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.

Circumstances:

The aircraft had been modified by the installation of an air driven winch for the purpose of towing gunnery targets and was operating in conjunction with a warship for scheduled sea/air gunnery practise. Weather conditions in the area were reported as overcast at 4000 feet, wind 060 degrees / 15-20 knots and visibility of 15-20 kilometres. At about 1717 hours the aircraft was instructed to commence carrying out gunnery tracking runs at an altitude of 1000 feet with the sleeve target not deployed. Between 1720 and 1735 hours the aircraft carried out two such runs from the west and east. The aircraft then tracked to the south, away from the ship to a distance of about 10 kilometres. At about 1738 the aircraft was instructed to turn inbound for a run from astern. At about 1739 hours the pilot reported engine problems and about one minute later advised "I've got problems, Mayday, I'm going in". Crewmen stationed near the stern of the ship, reported seeing the aircraft dive into the sea. The warship was immediately turned back towards the crash position. Other warships and aircraft were also ordered to the crash position. The only wreckage sighted was at the crash datum and was believed to have been a section of wing. This wreckage was located about two metres below the surface and sank before it could be recovered. The approximate depth of water at the crash position is 450 fathoms. No trace of the aircraft or its occupants has been discovered to date. The subsequent investigation established that the flight crew were properly qualified to conduct the flight, and that the aircraft was appropriately certified and maintained. The flight was conducted in accordance with the conditions of the operating contract. At the time of the occurrence the aircraft had not deployed the sleeve target, and no firing was being carried out. No evidence was found to suggest an in-flight structural failure or fire. The installation of the target towing equipment was not considered to have been a factor in the development of the accident. There was a loss of control of the aircraft following an apparent engine malfunction. The precise reasons for the accident have not been established.

Significant Factors:

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

1. Apparent engine failure or malfunction.

2. Control of the aircraft was lost for reasons which have not been determined.

Circumstances:

The aircraft, being flown by a pilot who had just completed type endorsement, was enroute Canberra - Talbingo - Albury at 6000 feet. Approaching Talbingo, the pilot noticed that the fuel gauges, which had each indicated three quarters full at Canberra, were indicating that only a small quantity of fuel remained. Suspecting that either a severe leak had developed, or he had made a serious error in fuel planning, the pilot elected to carry out an emergency landing in the Carabost area. To accurately report his position, the pilot attempted to tune the radio navigation aids to the Albury VOR, DME and ADF, without success. He then initiated descent and attempted, unsuccessfully, to transmit a MAYDAY call to Wagga Flight Service, Albury Tower and to broadcast on 121.5 MHz. On final approach to the selected landing point the pilot applied power, but the engine failed to respond. The aircraft touched down short of the intended landing point, bounced over a fence, and landed heavily in a paddock, collapsing the landing gear. The occupants evacuated the aircraft without assistance. Inspection of the aircraft the next day revealed that it had an adequate quantity of clean, water-free fuel in the tanks. Sufficient battery voltage was available to raise the flaps. The landing gear tracks on the ground indicated that the main landing gear had extended but had not locked down prior to landing. The descent had been carried out with throttle closed, mixture rich, carburettor heat on and cowl flaps open. To conserve fuel the pilot did not warm the engine during the descent. Consequently, low engine temperature, possibly combined with fouled spark plugs, prevented the engine from responding when the pilot sought power on final approach. The indication of low fuel quantity, combined with the inability to receive navigation aids and to transmit a radio message, plus the failure of the main landing gear to lock down are consistent with an electrical malfunction or low battery voltage. Overnight, the battery could have recovered sufficient charge to permit the flaps to be raised. Thus, an electrical malfunction and/or a loss of battery voltage, affecting the fuel quantity indicating system and misleading the pilot into believing that his fuel state was critically low, may have occurred.

Significant Factors:

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

1. An electrical malfunction and/or a low battery voltage may have occurred in flight.

2. The pilot was inexperienced.

3. The pilot misinterpreted the symptoms of the electrical problem as a low fuel state.

4. The pilot elected to carry out a forced landing in difficult terrain.

5. Following a prolonged descent at idle power with rich mixture, the engine suffered a loss of power on final approach. This accident was not the subject of an on-scene investigation.

Circumstances:

The pilot planned a pleasure flight which commenced in calm conditions. By the time the aircraft arrived back at the airstrip the wind was gusting north westerly at about 15 to 25 knots. The pilot assessed the wind direction and elected to land on the shorter north-south strip (about 330 metres long). On final approach the aircraft encountered strong turbulence and downdrafts. The pilot who had little experience in these conditions continued the approach until just prior to touchdown when he decided to go around and commenced a right turn. Whilst executing this manoeuvre the aircraft struck a log which was about 150 metres to the right and south of the strip.

Significant Factors:

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

1. A strong north westerly wind generated considerable turbulence making aircraft control near the ground difficult.

2. The pilot was inexperienced in windy and turbulent conditions.

3. The pilot attempted to go around from a low height.

4. The aircraft collided with a log.

Prior to takeoff the aircraft was cleared to track via a Standard Instrument Departure procedure referred to as (Runway) 21 Clackline 1. After takeoff the aircraft was observed to make an early left turn. The Tower controller kept the aircraft in sight to ensure that there was no confliction with another aircraft which was in the vicinity. It was determined that the crew of GIA 879 had flown a 21 Clackline 2 departure procedure. This procedure was on the adjacent page of the relevant document to the 21 Clackline 1 procedure.