The pilot-under-check was conducting his first circuit in the aircraft as part of a conversion onto the type. On final approach he realised that he had not selected carburettor heat, and moved to apply this control. However, he inadvertently pulled out the mixture control and all engine power was lost. Both pilots tried to return the mixture control to the full rich position, but found that the control could not be moved. The approach was being conducted in strong wind conditions and the instructor assessed that the airfield was beyond safe gliding range. He took control and turned the aircraft towards a cleared area. However, the aircraft overshot this area and collided with trees before coming to rest in a ditch. Examination of the mixture control revealed that the cable had broken due to metal fatigue. However, the cause of this fatigue was not positively determined.

After flying in the local area for a time, the pilot entered a long straight-in final approach for the easterly strip he had used for take-off. From a distance he observed that the wind was a light southerly. Following a slight bounce on touchdown, braking was initiated but the aircraft seemed to be travelling faster than normal. The pilot, believing that he had landed with a tail-wind, turned the aircraft to the north-east to increase the landing roll available. The aircraft overran the area into a fence and firebreak. The approach speed used was 12 knots faster than that recommended in the landing chart. The bounced landing, slippery grass surface and use of other than maximum braking increased the stopping distance required. The direction of turn chosen by the pilot to increase his stopping distance was downhill and with a tailwind component. The presence of telephone lines at the end of the strip precluded a go-around.

The pilot was conducting superphosphate spreading operations in fine and clear weather conditions. The paddock being treated sloped uphill, and there were heavily timbered peaks beyond the paddock. The pilot had spread the paddock the previous day under similar conditions. On this occasion the aircraft was apparently performing normally as the first swath run was completed, but the aircraft did not appear to gain any appreciable height as it approached the hills. It was then seen to adopt a steep nose-up attitude and commence a wingover type manoeuvre. During this manoeuvre the aircraft struck trees and then impacted the ground. A fierce fire broke out and engulfed the wreckage. Although the investigation was hampered by the extensive fire damage, no defect or malfunction was discovered which might have contributed to the accident. The reason the pilot, who had extensive agricultural experience, chose to conduct swath runs towards steeply rising ground was not determined. The wind direction had changed since the previous day, and the aircraft was likely to have been affected by downdrafts on the lee side of the hills. When the pilot realised the aircraft was not performing as expected, he evidently attempted to dump the remaining load and reverse the direction. However, there was insufficient aircraft performance available to successfully complete this manoeuvre.

Circumstances:

The aircraft had previously been parked for maintenance in a relatively confined area between two hangars. It was close to and facing a fence, in a position which did not allow sufficient room for a U-turn to taxi out. The grass surface was boggy after rain. The pilot sought assistance from a person in an adjoining hangar but there was no suitable tow bar, and the two could not manhandle the aircraft. The pilot then reversed the aircraft out until the wheels reached a small ridge at the edge of the taxiway. From this position there was then room to make a U-turn to the right. The pilot initially turned the aircraft slightly left to give himself more room before turning right. However, when he applied right rudder and brake, the aircraft failed to respond and continued ahead, sliding on the slippery surface. It then collided with a brick wall, damaging the nose cone and left wingtip and causing considerable damage to the wall.

After take off from runway 17, the aircraft commenced to roll and yaw to the right. The pilot maintained control, completed a left circuit and landed back on runway 17. Before take off, a flap setting of 20 degrees was selected and was indicating in the cockpit. Later inspection showed that at this flap selection, the right flap went to 20 degrees and the left to 40 degrees. Due to a maintenance error, when the left flap actuator was changed the hoses were re-attached to the wrong ports.

The pilot had just commenced a procedure turn at the end of a spray run, at a height of 200 feet above ground level, when the engine failed without warning. During the ensuing forced landing the aircraft landed heavily and overturned. The engine failure was caused by separation of number nine cylinder link rod end, which resulted in the piston lifting the head off the cylinder. The cause of the failure could not be positively determined, but was probably due to the link pin bush being worn away, and excessive tolerance between the link rod and link pin causing a fatigue failure of the link rod. Aircraft records showed that the engine had completed 184 hours since overhaul, but the internal appearance of the engine was that of an engine that had operated for a longer time. The reason for the unusual condition of the engine could not be established.

Circumstances:

At 1911 hours the pilot made a routine radio transmission stating that the aircraft was 20 miles (37 kilometres) north-west of Roma inbound and leaving 4000 feet on descent. He then spoke to the company at Roma on the company VHF frequency. The pilot did not respond to a traffic advisory call from Brisbane Flight Service at 1914 hours, and did not report his arrival at 1917 hours, the estimated time of arrival. Later, when the aircraft could not be located on the ground at Roma aerodrome, an aircraft which had previously departed Roma was diverted to search along the inbound track of the missing aircraft. An Emergency Locator Beacon (ELB) signal was later detected by a searching Army helicopter 19 kilometres west-north-west of Roma, and the wreckage was located at 0145 hours. The aircraft had flown into trees whilst in a shallow descent. Both engines were operating, and the wings were level at impact. The weather was fine, and the sky was clear, but it was a very dark night with no discernible horizon. There were no defects found with the aircraft that may have contributed to the development of the accident. The Minimum Safe Altitude for aircraft operating visually at night in the Roma area is 3000 feet above mean sea level (amsl). A visual descent may only be continued below 3000 feet at Roma when the aerodrome is in sight, and the aircraft is within 3 nautical miles. The accident site is approximately 1050 feet amsl. There was no evidence that the pilot was incapacitated, and the reason the aircraft descended below Minimum Safe Altitude was not determined.

Significant Factors:

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

1. The night was dark, without a visible horizon.

2. The aircraft descended below the Minimum Safe Altitude, for reasons which have not been determined.

The helicopter was being operated from a clearing in flat, tree covered terrain. It was heading into wind and had reached a height of about one metre after lift-off when it suddenly swung to the right and moved backwards. The tail skid and rotor struck the ground and the helicopter swung further right. The main rotor blades then contacted the ground and the helicopter rolled on to its side. The pilot reported that a local whirlwind had caught the helicopter just after lift-off. Overnight rain had prevented the tell-tale dust plume from developing. This accident was not the subject of an on-site investigation.

During a visual approach to Runway 32 the engine began to run roughly, to the extent that no useful power was available. The pilot made a "Mayday" call and elected to attempt a forced landing on Runway 05. In the latter stages of the approach it became obvious to the pilot that the aircraft would not reach the runway. It flew into a tall sugar cane crop and overturned at low speed. The cane cushioned the final impact. Investigation revealed that both magnetos contained leaking, obsolete coils. They had overheated, causing the ignition to fail. The coils were clear case coils which should have been withdrawn from service in the early 1970's in accordance with a specific Airworthiness Directive (AD). The AD had been withdrawn when it was considered that Licenced Aircraft Maintenance Engineers (LAMEs) in the aviation industry were sufficiently aware of the hazards posed by these coils and that all in-service clear case coils had been replaced. At engine runup, both magnetos had checked serviceable because the coils were cold. During the flight, they had heated sufficiently to cause an internal breakdown of their function, resulting in a significant power loss. The pilot misjudged the subsequent forced landing and the aircraft undershot the runway threshold.

The pilot was required to carry out a rope laying operations for the purpose of transmission line installation, between pylons. After take-off the pilot established a 20 feet hover, 10 metres west of one of the pylons. A worker standing on the ground was observed to be walking towards the helicopter holding in his right hand the rope attached to the pylon. As the rope became taut, it was struck by the the main rotor blades. Control of the helicopter was lost. The investigation was carried out by the Department of Civil Aviation Malaysia.