Circumstances:

The pilot planned a short flight to Bunbury prior to boarding an international flight from Perth Airport that afternoon. He dipped the fuel tanks and checked the fuel gauge reading against the fuel calibration card, concluding that the aircraft contained about 70 litres of fuel, which was sufficient for the intended flight. Enroute to Bunbury, the pilot noticed that the fuel usage appeared higher than normal but did not take any action to remedy the situation, beyond leaning the mixture. The pilot noticed that both fuel tank indicators were approaching empty when he broadcast the inbound to Bunbury radio transmission. He was not concerned, as a check of the fuel gauge calibration card indicated that there were still 40 litres remaining. Eleven kilometres from Bunbury, the engine stopped and except for one brief burst of power would not restart. The pilot attempted to enter a forced landing pattern two or three times but had to change the selected landing area on each occasion due to a proliferation of power lines in the area. The aircraft eventually touched down on the bank of a river and overturned. A check of the aircraft found that eight and a half litres of fuel remained in the system, this was three and a half litres less than the published unusable fuel for the aircraft. Perusal of the aircraft records indicated that an error had been made during the latest fuel gauge calibration, and the fuel gauge calibration card was inaccurate. It is probable that the aircraft contained much less than 70 litres on DEPARTURE. The pilot sustained facial lacerations when the aircraft overturned on landing. He was not wearing the shoulder portion of the lap/sash seat belt. It is probable that there would have been no injuries if the complete belt had been worn.

Significant Factors:

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

1. Inaccurate fuel gauge calibration chart.

2. Fuel exhaustion resulting in a forced landing on unsuitable terrain.

3. The pilot did not ensure that the complete seat belt was fastened.

Circumstances:

The Gliding Federation Australia investigation reports that after a winch launch the student pilot flew locally for about ten minutes. He then realised that he was getting low and turned back towards the airfield. Late in his approach he saw power lines, dived under them, and was forced to outland in a paddock adjacent to the airfield. At the end of the landing roll the glider collided with a fence and was substantially damaged.

Significant Factors:

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

1. Inadequate circuit planning, probably as a result of inadequate or incomplete training.

2. Lack of situational awareness.

The pilot was carrying out a flight around the Archerfield Training Area. Approaching the southern boundary of the area he heard a change in engine note. The tachometer confirmed a loss of some 200 RPM, however, all other engine instruments indicated normal operating conditions. Full throttle selection failed to produce any change in engine RPM. The pilot elected to divert to Southport for a precautionary landing. After joining the downwind leg of the circuit he found that he was unable to control the engine RPM with the throttle. As a result he was unable to slow the aircraft to the normal landing speed. He decided against shutting the engine down and making a glide approach, as he was concerned that if he misjudged the approach the aircraft could land in the built up areas north of the aerodrome. On downwind once again, the RPM decreased to a level which was too low to sustain level flight. The pilot chose the clearest area in front of him for a forced landing. The area was a swamp and the aircraft nosed over shortly after touchdown. The engine had been overhauled and re-installed in the aircraft, 78 (in service) hours before the accident. The throttle arm linkage had come loose at the carburettor, effectively denying the pilot control of the engine. Examination of the castellated nut, which held the linkage in position, found no evidence that it had been torqued correctly or that a split pin had been installed.

Circumstances:

The student was making his second solo flight. During the approach to land the student realised the helicopter was above the desired approach path. He elected to land on the grass surface a short distance beyond the helipad as he has been taught. The wind was blowing at 10 to 15 knots from the northeast, with the landing conducted in an east south east direction. The pilot said he began to enter the hover and turn the helicopter to the left, into wind. The aircraft continued the left turn, during which it began to move rearwards. The tail skid dug into the landing surface, resulting in the helicopter rolling to the left and striking the ground.

Significant Factors:

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

1. Improper compensation for wind conditions.

2. Pilot encountered unforeseen circumstances beyond his capability.

3. Improper operation of primary flight controls.

Circumstances:

The aircraft had been fitted with a tailwheel conversion prior to being imported from the USA. During a touch and go landing, the aircraft was decelerating in the three point attitude through about 20 knots, when the pilot lost control in a violent swing and wing drop to the right, followed by an immediate reversal to the left. The right main gear had separated from the fuselage during the landing roll. The main gear locating bolt and saddle bolts had been fitted incorrectly and were thread bound, allowing the gear leg to place abnormal loads on the saddle. It failed progressively until final overload failure during this particular landing. The aircraft had flown only 13 hours since being placed on the Australian Register. It was imported with the main gear undisturbed. The progressive mode of failure suggests that evidence of impending failure of the saddle should have been apparent for some considerable time.

Significant Factors:

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

1. Improper fitment of Tailwheel Conversion Kit by USA maintenance organisation.

2. Overlength bolts holding right main gear were thread bound before the correct clamping tension was achieved.

3. One of the two cast metal saddle sections which locate the gear leg laterally in the fuselage had failed due to fatigue and overload.

4. During the inspection for the issue of a Certificate of Airworthiness, the maintenance organisation did not discover the incorrect installation of the tailwheel kit.

The pilot was tasked to take a passenger to Porphry and bring further passengers back to Kalgoorlie. The flight proceeded normally until shortly after cruise power was selected when the engine began to surge. Attempts by the pilot to rectify the surge were unsuccessful. He turned the aircraft towards Kalgoorlie and, when the oil pressure dropped to zero, the cockpit filled with smoke and the windscreen was smeared with oil, he elected to land on the salt lake almost directly below the aircraft. The landing was uneventful until the nosewheel broke through the lake's crust and the aircraft nosed over and stopped inverted. The loss of oil pressure, the smoke in the cockpit and the oil smear on the windscreen were a result of a hole puntured through the engine crankcase at the base of number 4 cylinder. The conrod of the number 4 piston had suffered a fatigue failure due to a metal embrittlement, brought about by molten material from the number 4 big end bearing coming in contact with the conrod. It is probable that the big end bearing had overheated due to a lack of lubrication, although no evidence was found of a restriction in the oil supply lines. The metallurgical examination concluded that the fatigue failure had developed over a short time and that there was evidence that the number 3 big end bearing had also been overheated due to a lack of lubrication. The pilot chose the site for the forced landing knowing that there was a chance that the surface would be soft. His choice was made after considering that the alternative landing sites were less suitable for a variety of reasons.

The pilot was engaged in a local flight and was practising hovering at various altitudes. With the helicopter heading 320 degrees, the pilot commenced a slow descent from about 15 feet. The wind was 310 degrees at 10 knots gusting to 20 knots. While descending to about three feet, the helicopter began a slow yaw to the right through 30 degrees. The pilot elected to let the yaw continue and carry out a 360 degree pivot turn. After turning through about 100 degrees, the pilot stopped the descent by increasing power and pulling on collective. Coincidentally, the pilot reported that the helicopter then rapidly increased the rate of turn despite the application of full left anti-torque pedal. After about one turn, the pilot said he lost all control and following about another 3-4 turns, the helicopter crashed onto its left side at about 45 degrees angle of bank. During the sequence several mainrotor blade ground strikes occurred. The pilot said that he was also aware of overcontrolling on the cyclic control and pulling on collective at one stage in his efforts to control the helicopter. The investigation could not find any mechanical cause for the loss of control. Both the pilot and passenger reported that at no time did the passenger touch the controls or have his feet near the anti-torque pedals. Studies on helicopter tail rotor vortex rings indicate that these rings can form with a relative wind from 220 to 320 degrees at 10 to 25 knots, with further indications that the worst areas are around 250 and 290 degrees relative. In addition, the conditions suitable for the formation of a vortex ring are most favourable when the tail rotor is moving to the left, as in a right pedal turn. At the point where power was increased, the tail rotor was in a critical position with a relative wind from 250 degrees and strength from the left of between 10 and 20 knots. If the tail rotor was close to a vortex ring state, increased power would, through the torque effect, produce a marked right yaw. Due to the vortex ring, left pedal input would have no effect.

While flying downwind at 30 knots about 50 feet above the ground, the pilot attempted to increase power to accelerate the aircraft. There was no response from the engine, and engine and rotor RPM fell as he applied collective pitch. He attempted to slow the aircraft to land but the heel of the left skid hit the ground and the helicopter rolled on to its side. Examination of the helicopter revealed that a very close tolerance fitting in the linkage between the throttle valve and the mixture control valve caused severe binding. This prevented normal throttle movement.

Following the completion of a flight in the local training area the aircraft was landed on Runway 36 at Roma. At the time the wind was north-westerly at five to eight knots and there was a thunderstorm to the south-west of the field. During the landing roll the wind velocity suddenly increased to about 25 knots. The aircraft swung to the left and ran off the side of the runway. The pilot was unable to regain directional control but shut down the engine before the aircraft ran into a ditch. This accident was not the subject of an on-site investigation.

The pilot noticed what sounded like a slight misfiring noise coming from the engine after start up, however, all other indications, including a magneto check, were normal. The pilot flew the aircraft to a one metre hover, carried out a power and handling check, which was normal, and entered translational flight for a DEPARTURE from the heli-pad. Shortly after entering translational flight the aircraft began to descend. The pilot opened the throttle and raised the collective lever, however, this did not correct the descent. The pilot observed that both engine and rotor rpm were decreasing. At this point the aircraft was approaching a one metre high post and wire fence and the pilot assessed that the aircraft would clear the fence and touchdown in the open area on the other side of the fence. Both skids collided with the top of the fence causing the pilot to lose control of the helicopter which fell to the ground on the far side of the fence. A post accident engineering inspection disclosed that the movement of the exhaust valve in the No. 2 cylinder was restricted by a build up of carbon deposits. The top end of the engine had been overhauled, in Canada, 442 hours prior to the accident. It is likely that the sticking exhaust valve caused the loss of power reported by the pilot. Sticking valves is a known problem with the engine model fitted to the accident aircraft and the manufacturer, the Civil Aviation Authority and the operator had already taken action to correct it.