As the aircraft was cruising at 2500 feet above mean sea level the pilot noticed a vibration in the airframe. He reduced the manifold air pressure setting slightly and the vibration stopped. A short time later the aircraft lost directional control and began to spiral to the right. The pilot was unable to stop the rotation and when the helicopter landed it rolled over. Investigation showed that the lower vertical fin attachment brackets had failed, which caused the fin to separate in flight and strike the tail rotor. The tail rotor assembly and gearbox then completely detached from the tail boom. The fatigue failure of the fin was caused by vibrations emanating from worn components and bearings in the tail rotor and its gearbox. These parts were recently taken from another helicopter and fitted to the subject machine, their previous condition could not be determined. A recent service inspection failed to detect the worn components or the weakened lower fin. The wear in these components was also not noticed during the pre-flight inspections that were carried out between that service and the accident flight.

About 5 minutes after his estimated arrival time the pilot reported that he was uncertain of his position. Attempts to locate the aircraft were unsuccessful until the pilot climbed to 6000 feet and 22 minutes after the initial call the aircraft was radar identified 78 kilometres north of Sydney. The aircraft was vectored towards Bankstown but about 9 kilometres from the aerodrome the pilot advised that the aircraft was out of fuel. A forced landing was carried out onto a suburban street, during which power lines and a power pole were struck. The aircraft had departed with adequate fuel to conduct the flight. The pilot had only limited experience with night operations and had not maintained a detailed navigation log. He had apparently not been aware of the critical fuel state of the aircraft until about 10 minutes before the engine failure, which occurred 56 minutes after the position uncertainty was reported.

The pilot was engaged in spreading fertilizer on a forest. The airstrip being used was in a valley and to fly to the area of operation the aircraft had to cross a ridge line. As the aircraft approached the ridge the pilot stated that he noticed that the aircraft was descending, he applied full power and jettisoned the load. However, the stub wing of the aircraft struck some tall trees below the top of the ridge and a short distance later the forward flight of the aircraft was arrested when it collided with a large tree. The aircraft slid down the tree and became wedged between it and two other trees. The pilot was able to evacuate himself from the wreckage and walk to the airstrip. The pilot had taken 19 loads across the ridge line en-route to the treatment area prior to the accident flight. He had been clearing the tree- tops on the ridge by 30-60 feet on each run and planned to do the same this time. However, as the aircraft approached the ridge line the pilot reported that it encountered a downdraught. The presence of downdraughts in the area could not be substantiated by either other pilots or meteorology reports.

During the approach the pilot became aware that the aircraft was going to undershoot the intended landing area. He adjusted the approach, however, the aircraft landed short of the aerodrome in a cultivated field and struck an earth bank. Witnesses reports indicate that the air brakes had been deployed prior to the glider turning final. It is possible that the pilot was distracted by the other aircraft and forgot that the air brakes had been deployed during the approach. This accident was not the subject of an on-site investigation.

The pilot in command estimated that there were approximately 26 gallons of fuel in the tanks before the flight commenced. They intended to conduct exercises in the training area for about 20 minutes, followed by a series of circuits and landings. Shortly after takeoff for the fifth circuit, the engine failed. The pilot in command took control, selected the landing gear down, and attempted to hold the aircraft off the ground until the gear had extended. However, touchdown occurred with the gear only partially extended and the aircraft slid to a halt on the runway. The aircraft had not been refuelled following a flight of 4.8 hours duration. The estimate of the fuel remaining onboard the aircraft was based on the reading from a fuel metre that subsequently proved to be unserviceable. When the engine failed, due to fuel exhaustion, the aircraft had been airborne for 1.1 hours and the exhaustion of the fuel supply was consistent with the flight time since the last refuel.

Shortly after the take-off run was commenced, a large stone was thrown up by the right mainwheel and struck the spray boom. The pilot dumped the load and returned for a landing. The strip was rough and undulating and during the landing roll the aircraft overran a depression and became airborne. The right main gear VEE assembly tube failed in overload when the aircraft subsequently landed heavily. The right wing then struck the ground and the aircraft ground looped. The pilot turned off the electrical system and vacated the aircraft, but shortly afterwards a fire broke out and consumed the aircraft.

Gliding operations during the day had been conducted on Strip 19. On this occasion the pilot planned to approach to that strip but to land on the cross Strip 09, to allow the glider to complete its landing near the club hangar. During the turn onto final approach, to Strip 09, the pilot noticed a tug aircraft apparently making an approach to the same strip. He continued his turn in order to avoid any conflict with the tug, and the aircraft subsequently touched down across Strip 19. It then ran through a ditch before colliding with a fence. The tug pilot stated that he saw the glider and thought that it would land on the left side of Strip 09. The tug aircraft was not fitted with a radio which denied two-way communications between the two aircraft. The two aircraft came into close proximity and the glider lost excessive height as the pilot forgot to retract the airbrakes during the turn to avoid the tug aircraft. The tug pilot continued the approach and landed but the glider pilot was committed to a downwind landing and attempted to land across the other strip.

Shortly after takeoff, the pilot discovered that the aircraft had suffered an electrical failure and he elected to return and land. On selecting the landing gear down, he advised that he felt the aircraft slow down and thought that the gear was extended. No gear position lights were available because of the electrical malfunction. During the landing flare the pilot realised that the aircraft was lower than normal, and applied full power in an attempt to go around. The aircraft settled onto the runway with the gear retracted before the power application was able to take effect. The reason for the electrical failure could not be determined. The pilot was unaware that, although the gear extension system is hydraulically actuated, the hydraulic pump is electrically operated and thus did not function following the electrical failure. This accident was not the subject of an on-site investigation.

The student was receiving training in crosswind take-offs and landings in 5 to 10 knot wind conditions. For the third take-off in the sequence a minimum ground roll technique was employed. The aircraft lifted off in a slightly nose-high attitude but did not appear to be climbing or accelerating. The instructor took control but was unable to improve the aircraft performance and the right wing and maingear collided with a fence. The gear leg was detached, and shortly afterwards the aircraft touched down in the paddock beyond the fence. The nosegear collapsed and the aircraft slid sideways to a halt. No defect could be found with the aircraft which may have contributed to the accident. Neither the instructor nor the student had noted the engine rpm or the indicated airspeed prior to, or at lift-off. It would appear that the airspeed at lift-off was lower than the recommended speed and that the nose high attitude subsequently maintained prevented acceleration to gain adequate flying speed. Prior to take-off the wind direction was seen to be varying and it is possible that a slight downwind component may have affected the performance of the aircraft.

The pilot was aware of powerlines associated with the treatment area. He had completed spraying one area, and while waiting for the markers to move to the next area he completed two short runs in the vicinity of the powerlines. He became agitated at the length of time it took the markers to get into position, and when he commenced the first long run he had forgotten about a powerline which crossed his flight path. The upper section of the fin struck the wire, resulting in control difficulties for the pilot. He decided to land ahead rather than attempt to return to the authorised landing area. The aircraft passed through two fences before coming to rest nose down in a gully. There is evidence that the pilot was fatigued. This accident was not the subject of an on-site investigation.