The pilot, who was also the holder of a Private Pilot Licence, was conducting his first gliding flight for the day. The glider was aero-towed to 1100 feet above the aerodrome, but only weak lift was encountered in the area. The pilot elected to return for landing and commenced a normal circuit. On the downwind leg strong sink was encountered and the base turn was conducted at about 300 feet above the ground. Indicated airspeed at the time was reported to be about 55 knots. The pilot subsequently advised that the roll into the turn was normal, but he was unable to level the wings again, even with full opposite aileron. The aircraft continued descending in a wing-low attitude and struck the ground about 250 metres before the threshold of the strip. Investigation revealed no evidence of any pre-impact defect or malfunction of the controls, and atmospheric conditions at the time were reported as being stable. When the sink was encountered on the downwind leg, the pilot had modified his circuit by flying closer to the strip. As a result, the angle of bank required for the base turn was steeper than normal. It was considered probable that the aircraft had stalled during this turn onto base, with insufficient height remaining to allow the pilot to recover control.

The aircraft returned to its departure aerodrome after suffering a complete electrical failure. Emergency extension of the gear was attempted, but during the landing roll the nose leg retracted, which resulted in the nose and propellers striking the runway. A written checklist was not used prior to departure and the generators were evidently not switched on. The electrical panel and the generator warning lights are obscured by the control column. Emergency gear and flap extension is achieved using the same winder which is placarded "Flaps-push handle in, Gear-pull handle out". Investigation revealed that although the flaps were in the fully down position the gear was only part of the way through its extension cycle.

The aircraft was using a taxiway which had a row of cones positioned about 11.5 m from the centre-line to indicate a step in the sealed surface. The pilot saw a fuel tanker parked some distance away from the cones, but, assuming that the cones were taxiway clearance markers,continued to taxy along the centre-line. The port wing struck the top of the tanker about 15 m from the aircraft centre-line and about two metres from the wing tip. There were works in progress in the area of the occurrence. Tanker drivers were required to park their vehicles not closer than 24 m to the centre-line of the taxiway, but there was no visual delineation of this distance.

The pilot was turning into the parking area, intending to taxy between aircraft parked in parallel rows. As the turn was completed the left wing tip struck the spinner of the aircraft at the start of the left hand row. This aircraft was undamaged, however the wing tip of the taxying aircraft was pushed rearwards with consequent damage to the rear spar fuselage carry-through member. During the turn into the parking area one of the passengers interrupted the pilot's concentration by pointing out that the parking position from whence they had departed, was still vacant. The pilot did not notice that the aircraft had moved almost 2 metres to the left of the taxiway guideline until the collision was imminent.

The pilot was conducting a night cross-country exercise to maintain his recent experience requirements. On final approach he realised that the aircraft was undershooting. Some engine power was applied and the approach was continued but the pilot then saw power lines ahead, too late to take any avoiding action. The aircraft struck the wires and subsequently impacted the ground 211 metres short of the threshold. It came to rest 91 metres further on after colliding with a fence. The wires struck provided power for the airfield lighting, which was extinguished at the time of collision. The power lines struck were 28 feet agl and were 600 metres from the threshold. The pilot had been slow to realise that the undershoot situation was developing and had not taken appropriate action to either regain the normal approach path or to go-around.

The aircraft was cruising at 10,000 feet at night, when the passenger noticed the manifold pressure reducing. The engine rpm also dropped and the pilot changed fuel tanks, switched on the fuel boost pumps and moved the throttle and pitch controls to the fully forward positions. At about the same time the manifold pressure and engine rpm readings reportedly dropped to zero. The aircraft was set up in a glide and despite several attempts engine power could not be restored. The pilot tracked the aircraft towards a town and descended over the town before taking up a westerly heading in preparation for landing. At about 20 feet above the ground the aircraft struck a tree and then landed heavily on a steep bank. An inspection of the engine found that the crankshaft had failed due to a fatigue fracture initiated from a manufacturing fault. An Airworthiness Directive regarding inspections of crankshafts in this type of engine has since been introduced.

At a height of about 80 feet above ground level with little forward speed, the helicopter suffered a complete power loss. During the subsequent autorotational descent the main rotor struck trees, and the right skid was torn off on impact with the ground. Investigation revealed that two connecting rods had become detached from the crankshaft, and the engine had seized. It was likely that a previous overspeeding of the engine had stretched the big end bolts. This led to a loss of torque on the nuts retaining the bolts, which finally suffered overload failures.

Thirteen minutes after departing Brisbane the crew was instructed to "contact Brisbane Control now on 127.2" (the next VHF en route radio frequency). This message was received at 1023 E.S.T. and acknowledged. At 1039 hours, Brisbane Flight Service received a radio check call from the aircraft on HF. However, despite numerous calls from Brisbane, Sydney, and Melbourne Airways Operations units, nothing further was heard from the aircraft on VHF until 1144 hours when the crew contacted Sydney Control requesting transfer instructions to Melbourne. The aircraft's progress was monitored on radar throughout the flight and, as it appeared to behaving normally, no fears were held for its safety. In his report, the Captain stated that both VHF radios had been inadvertently selected to 127.3 MHz instead of 127.2 MHz. Both pilots had heard aircraft communicating on this frequency, which is a Melbourne-Sydney route frequency, and believed communications were normal. Neither pilot could recall transfer instructions being issued, or calling Brisbane Control on frequency transfer. Examination of taped air/ground communications did not reveal any record of the crew having checked-in on frequency 127.3 MHz following transfer, as required by standard procedures.

The aircraft was on climb towing a glider when the pilot saw smoke and flames around the left rudder pedal area. The glider was released and the pilot landed the aircraft in a paddock. He abandoned the aircraft before it was destroyed by fire. Because of the severity of damage the cause of the fire could not be determined. It was established that the fire melted fuel lines in the cockpit walls and fuel released then fed the fire which completely gutted the aircraft.

The pilot had flown from Adelaide to Bacchus Marsh, on 25 July 1980, and had left the aircraft there while he attended to private matters. On his return during the afternoon of 1 August he discovered that there was no fuel available, and elected to fly to Essendon to refuel and to obtain a pre-flight briefing. It had been the pilot's intention to proceed as far as Horsham and remain overnight before continuing, however the weather forecast was satisfactory and he decided to plan a Night VMC flight to Adelaide. The pilot noted on the plan that the lowest safe altitude on the initial leg to Yarrowee was 3500 feet above mean sea level (amsl), and was 4800 feet amsl between Yarrowee and Mt William. Planned cruising altitudes were below 4000 feet amsl to Yarrowee, thence below 5000 feet amsl. About 25 minutes after DEPARTURE the pilot was advised that the weather at Adelaide was deteriorating and he elected to divert and land at Horsham. Amended flight details were passed, indicating that the aircraft would proceed to Horsham from over Mt William, cruising below 5000 feet amsl. At 2049 Melbourne Flight Service contacted the pilot and requested an estimated time of arrival for the Mt William position. The pilot replied that his revised time for the position was 2051. This was the last transmission received from the aircraft. At about 2050 witnesses noted an intense fire near the summit of Mt William. The following day it was established that the aircraft had collided with the almost vertical face of the mountain, some 400 feet below the summit, while apparently in cruising flight at about 3400 feet amsl and on the track from Yarrowee. The wreckage had then fallen about 200 feet to sloping ground and had been consumed by an intense post-impact fire. The weather at the time of the accident was reported as fine, with good visibility. Although the winds were stronger than forecast, it was considered that there was no significant turbulence or downdrafts in the area. The examination of the wreckage was hampered by the extent of the damage, however no evidence was found to indicate any pre-impact defect which might have contributed to the development of the accident. The reason the pilot was flying the aircraft more than 1000 feet below the lowest safe altitude for the route sector could not be determined.