The pilot was conducting the final stage of a night freight flight from Melbourne to Hobart and return. Because of traffic in the Melbourne/Essendon area, the aircraft was radar vectored to the south of Essendon. In the vicinity of the Westgate Bridge the pilot was instructed to carry out two orbits, in order to facilitate his approach to Melbourne. These orbits were conducted with the aircraft in cloud. The pilot was then instructed to take up a north-westerly heading, and to descend to 2000 feet (above mean sea level). On gaining visual contact with the ground, the pilot saw an aerodrome ahead, which he assumed was Melbourne. The aircraft was too high for a direct approach to this aerodrome, and the pilot requested approval to carry out a further orbit. The aircraft was advised to take up a westerly heading, and the pilot was instructed to call the Melbourne Tower controller. The Tower controller at Essendon was aware that the aircraft was enroute to Melbourne. After he observed the aircraft passing abeam Essendon, he cleared a waiting aircraft to take-off into the south. Shortly afterwards, he saw the first aircraft commence a descending turn to the left and track towards Essendon. The controller alerted the Melbourne Tower controller to the situation, and instructed the aircraft which had just become airborne to turn to the left. The pilot of this aircraft saw the approaching aircraft, and adjusted his flight path accordingly. The two aircraft passed with about 200 feet of vertical separation, and were some 200 metres apart horizontally. Melbourne Tower advised the inbound pilot he was tracking for the wrong aerodrome, and instructed him to carry out a go around. At this time the pilot realised his error, and the remainder of the flight was uneventful. It was determined that the pilot had become disorientated as he gained visual contact with the ground. When he sighted an aerodrome, he had a fixation that it was Melbourne, and he had disregarded visual and aural cues that he was proceeding to the wrong aerodrome. He was not familiar with the area, and it is highly likely that he was suffering the effects of fatigue.

The culler had just made a kill and the pilot prepared to land so that the beast could be bled. He selected an area of short grass and set the helicopter down with the engine over the barest area. Prior to landing the pilot briefed the culler on the need to deplane quickly to minimise the risk of a ground fire from grass ignited by the hot exhaust. The pilot intended to take-off as soon as possible and return for his passenger when the ground task was finished. Soon after the passenger had deplaned, the pilot was attempting to build up the rotor RPM when he became aware of smoke and flames. He reported that the engine was not responding to throttle input, and when he pulled the collective for liftoff, the engine lost all power and the helicopter settled onto the ground from a few feet. The aircraft was enveloped in flames as the pilot left the cockpit, and it was destroyed by fire. A fenceline cleared of grass existed some 70 metres away, but the pilot was intent of remaining clear of dust areas to prevent wear in the tail rotor assembly. He judged that there was a minimum risk of fire in the area selected for landing, and it was clear of the obstruction posed by the fence. There were no reported aircraft defects or fuel leaks.

The aircraft was spreading Mexican Sulphur, a mixture of sulphur and a carrier base. Operations were being conducted from a one-way strip in a 2 to 3 knot tailwind, and an appropriate reduction in payload had been made by the pilot commensurate with the conditions. It was reported that operations had proceeded slowly as the spreading medium would not flow freely, tending to clog in the clamshell gate. This required the pilot to work the gate continuously to achieve an even discharge. A witness reported that during the sixth takeoff of the day, a strong wind gust substantially increased the tailwind. The aircraft did not become airborne, and the pilot pulled the hopper handle in an attempt to reduce the weight of the aircraft in order to clear a boundary fence. The load failed to dump normally. The pilot then selected additional flap and the aircraft became airborne in a tail-low attitude. Although the mainwheels cleared the fence, the tailwheel struck a fence post. The aircraft remained airborne, but the pilot found it necessary to hold the control column in the fully-forward position. After some altitude was gained, the pilot made a further and successful attempt to dump the load. Although difficulty was experienced in controlling the aircraft, a safe landing was made at another aerodrome nearby. The aircraft sustained substantial damage to the rear fuselage and empennage. Empennage damage included buckling of the tailplane and rudder trailing edge. It was also found that spreading medium had clogged the hopper gate, preventing emergency dumping of the payload, and the hopper gate mirror was incorrectly aligned so that the pilot was unable to observe load release. This accident was not the subject of an on-site investigation.

The helicopter crew was responding to an emergency call. The aircraft was cruising at 1500 feet above sea level, at about 120 knots, with maximum continuous power applied. As descent was commenced there was a loud bang, followed by severe vibration. The helicopter was briefly out of control and the vibrations were such that the pilot was unable to read the instruments. Power and speed were reduced and the pilot was able to regain control. Because of expected difficulties with control near the ground, the pilot elected to carry out a water landing, some 80 metres from a beach. A subsequent investigation determined that the left engine access cowl had become unlatched, lifted and been struck by the main rotor blades. The hinged section had been struck at least twice and the upper fixed cowl, which had been torn from its fastenings when the hinged cowl lifted, at least once. Apart from minor impact marks to other main rotor blades, a piece of cowling had slid along one blade, causing 2.1 metres of the outboard trailing edge to separate, resulting in severe unbalance to the rotor disc. The pieces of engine cowling and main rotor blade were found approximately two kilometres south of the accident site. As two lower main cowl latches were not recovered, the reason for the cowl becoming unlatched could not be positively determined. However, during the investigation, it was found that the lower cowl latches, which appeared to be correctly locked and engaged, could release when the cowl was subjected to simulated inflight loads. The manufacturer has suggested modifications to improve the cowl latching system.

Reccomendations:

It is recommended that the Civil Aviation Authority evaluate the suggested modifications and, if satisfactory, direct their incorporation in Australian registered Kawasaki BK117 aircraft.

The aircraft underwent a 100 hourly inspection six days prior to the accident. During that inspection three oil leaks were rectified. When the aircraft commenced operations again after the 100 hourly inspection, the engine again started to leak oil at a significant rate. The operation was remote from the maintenance organisation. The pilot did not determine the source of the oil leak nor monitor the oil consumption rate during the days prior to the accident. On the day of the accident the pilot had been spreading superphosphate since late morning. He had finished that task and had commenced spreading clover seed. On the second seeding sortie he sensed a loss of performance. He pushed the throttle lever forward but the engine did not respond. He checked the RPM and noted it was 2200 and decreasing. He then noted that the oil pressure was indicating zero. At this stage he was about 50 feet above the ground and operating in mountainous terrain. He turned the aircraft to the right to avoid an area of trees and try to land on a steep upslope. The aircraft stalled into the upslope and came to rest after a 25 metre ground-slide. The investigation revealed that the oil filter bolt and sleeve had failed as a result of high cycle low stress fatigue. This was consistent with the retaining bolt being under-torqued. This resulted in the oil filter separating from the engine, a consequent loss of engine oil and finally, loss of engine power.

According to his log book, the pilot had flown the aircraft on two previous occasions of about 15 minutes duration each. The pilot was briefed by the owner of the aircraft on power settings and speeds. He then took-off into the south from the strip which is aligned approximately north-south. There was a light southerly breeze blowing at the time. The aircraft was seen to make one right-hand circuit, but it could not be determined if the aircraft actually made a landing from that circuit. When the aircraft was on final approach from a second right-hand circuit at an estimated altitude of about 200-300 feet, it entered a turn to the right. As the turn progressed onto a northerly (downwind) heading, the angle of bank became progressively steeper until it was about 90 degrees. The nose then dropped and the aircraft dived to the ground. The first persons on the accident scene experienced difficulty in removing the pilot's motor cycle type safety helmet (with full face enclosure) before resuscitation could be applied. The investigation did not reveal any pre-existing defects that may have caused the accident. Other pilots reported some turbulence and windshear in the area where the accident occurred. The area was inspected by an officer from the Bureau of Meteorology who specialised in micro-meteorology. His opinion was that turbulence or windshear effects at the time of the accident would have been minimal. The pilot had been receiving dual flight instruction from an ultralight flying school. After a dual instructional flight on the morning of the accident, he had been strongly advised by his instructor not to fly solo until he had completed more dual instruction as the instructor believed that the pilot was not sufficiently competent to fly solo. The pilot lost control of the aircraft for reasons which were not determined.

The aircraft was engaged on a charter operation from Merimbula to Moruya, Nowra and Bankstown. The aircraft operation was normal until the DEPARTURE from Nowra. After takeoff when the gear was retracting, the pilot noticed a momentary dimming of the cockpit lighting. The gear indications were that the normal retraction cycle had been completed with red light on. The flight continued to Bankstown but when the gear was selected down, nothing happened. The pilot then noticed the landing gear motor circuit breaker had tripped. All attempts to reset it were unsuccessful. The aircraft was then flown to the training area where the pilot tried unsuccessfully to lower the gear manually. The aircraft returned to the Bankstown circuit where it was verified by ground observers that the gear was still retracted. When all emergency services were in place the pilot carried out a wheels up landing on runway 29 centre. The aircraft slid for 325 metres before coming to rest on the runway centreline. Substantial damage occurred to the underside of the fuselage and both propellers were bent. Subsequent investigation revealed the landing gear dynamic breaking relay had failed in the UP position which allowed the motor to drive the retract actuator past the full UP position and jam it on the UP stop. An internal inspection of the relay found that the UP relay contact points were badly pitted and burnt from arcing.

The aircraft was making a landing approach to Sydney when the pilot observed the nose gear had failed to extend normally, after the landing gear was selected down. The aircraft was diverted to Bankstown where it was subsequently established that the nosegear trailed about 20 degrees from the locked down position. All attempts to extend the nosegear were unsuccessful. The aircraft was subsequently landed on the 36L grass strip. During the landing roll the nosegear collapsed and the aircraft settled onto its nose. Prior to making the approach and landing, the pilot said he had shut down the right engine and feathered the propeller, which was then parked in a horizontal position. On short final, the left engine was shut down and the propeller feathered. Insufficient time was available to park the propeller, which struck the ground in a vertical position. This resulted in the left engine crankshaft being fractured, at the rear of the propeller hub mounting. It is considered that the nosegear failed to extend following the failure of the aft rod end of the nosegear aft retract rod. A subsequent specialist examination determined that excessive forces were imposed on the rod end due to landing gear misrigging, following replacement of that component during a recent maintenance inspection. The aft rod end subsequently failed as a result of continued overloads.

The pilot commenced mustering at about 0500 hours, flew for three hours, then carried out routine station duties until it was time to muster another paddock. After approximately 20 minutes airborne he decided to land for a drink of water, which he carried in the helicopter. As the helicopter passed through 10-15 feet on approach, the pilot heard a loud noise, which only lasted for a moment, then the helicopter began to rotate. He lowered the collective and landed the machine upright after two revolutions. Investigation revealed that the tail rotor assembly had hit a small mulga sapling, causing the tail rotor and gearbox to separate from the helicopter. The pilot could not recall having sighted the sapling as he approached to land. Outside air temperature at the time of the accident was plus 38`C.

The pilot was completing a 50 hour test flying program on the aircraft. Two previous sorties had been flown during the day, without incident. On this occasion, the pilot was conducting a glide approach, but when power was re-applied to go around, the engine delivered some 400 rpm less than normal. The pilot attempted to conduct a low level circuit, however the engine power continued to decay on the downwind leg. The turn onto base leg was conducted at about 100 feet, and shortly afterwards all power was lost. The aircraft landed heavily in a paddock. A post accident test run and inspection of the engine found that the power loss was caused by a spark plug failure. This accident was not the subject of an on-site investigation.