Circumstances:

At the completion of a trial instructional flight a normal flare and two-point touchdown was accomplished. On touchdown the pilot noticed a "tug" on the airframe and the elevator control became "stiff". Inspection revealed the tailwheel forward attachment bracket had failed from fatigue. This caused the tail of the aircraft to ride over the broken tailwheel forward arm, resulting in the tailwheel folding aft into the tail cone. The rear attachment then failed in overload allowing the tailwheel to separate from the aircraft.

Significant Factors:

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

1. The tailwheel front attachment bracket failed due to fatigue cracking.

2. Aircraft inspection failed to detect the crack.

The pilot in command, who was also the owner of the aircraft, was acting as the safety pilot for the other pilot, who had only recently received training on the aircraft. This was the first occasion on which the co-pilot had flown the aircraft from the right hand seat. He flared the aircraft too high on the first circuit and was advised by the pilot in command that the flare had been commenced too early. As he attempted to reposition the aircraft closer to the runway it struck the runway heavily and bounced. The co-pilot inadvertently closed the throttle and the aircraft struck the runway in a nose down attitude. Damage was caused to the propeller, engine firewall and the landing gear.

A ten minute flight in the local area had been completed without incident. After DEPARTURE for a second flight the helicopter was climbed to 150 feet agl to allow the passengers to view the campsite and a herd of animals. The pilot and passengers then heard a loud bang which was followed by a severe airframe vibration. The noise and vibration continued and the pilot elected to carry out an autorotational descent and land in a small clearing. The clearing was overshot and the helicopter struck several trees. Investigation indicates that the engine cooling fan drive belt, which rotates at high rpm, failed. The flailing belt then tore a section of the canvas cooling fan shroud. Vibration was produced when the broken belt and section of shroud were ingested into the cooling fan.

Following a normal approach for a night landing, touchdown was made on the main landing gear. The pilot then noticed that the nose was lowering by an excessive amount, and he carried out a successful go around. Examinations from the ground and from a helicopter equipped with a searchlight revealed that the nosegear was inclined at about 30 degrees to the vertical. The position of the nosegear did not alter when the gear was cycled. After all attempts to lower the nosegear were unsuccessful, the pilot elected to carry out a landing with the maingear retracted. He was unable to use the grass flight strip alongside the lighted runway because of obstructions, and chose to land on an unlit strip. The left engine failed because of fuel exhaustion when the aircraft was on final approach. After touchdown, the aircraft slid off the end of the strip and came to rest against the boundary fence. It was determined that the nosegear retract rod plunger had failed from fatigue, resulting in the nosegear being isolated from the remainder of the landing gear system.

While hovering over scrub at about 30 feet agl, the engine lost power. The pilot was able to manoeuvre the aircraft to overhead a clearing but rotor rpm decayed and the aircraft landed heavily bending the landing gear rear cross tube and a section of the tail boom. The power loss resulted from the incorrect fitment of rocker arms during a previous servicing.

Shortly after touchdown the left wing began to drop and the aircraft veered off the runway. It came to rest after colliding with a runway light and a culvert. Inspection revealed that the castellated nut from the left gear torque link pivot bolt was missing. This allowed the lower torque link to rotate with the wheel and separate from the upper torque link. It was evident that a split pin which should have locked the castellated nut had not been in place for a considerable time, thus allowing the nut to work loose. However, the reason the pin was not in place could not be positively established.

A low level aerobatic display was being conducted over the lake. Towards the end of the display the pilot performed four snap rolls followed by a steep climb and stall turn. Although the display was to be conducted not below 500 feet agl the aircraft was recovered from the last snap roll at an estimated 150 feet agl. Despite this low recovery height the pilot persisted with the climb and stall turn manoeuvre. While attempting to recover from the subsequent dive he stalled the aircraft at too low a height to avoid impacting the water.

Circumstances:

The pilot reported the flight was uneventful until the landing gear failed to extend normally prior to landing at Quirindi. Normal and emergency procedures were unsuccessful. The aircraft then diverted to Gunnedah where ground observers reported the landing gear appeared to be extended, however, the right main gear collapsed during the landing roll. Investigation revealed an internal failure of the landing gear air/ground safety switch which rendered the gear door solenoid valve inoperative. The failure had apparently occurred during the initial landing gear extension cycle prior to the locking sequence of the right main gear. All subsequent hydraulic action was then directed to the selector handle lock valve, preventing completion of the landing gear extension cycle.

At the completion of a flight in the training area, the pilot returned for a full stop landing on the duty runway. A preceding aircraft in the circuit advised the Tower that sun glare would soon be a problem for landing aircraft. Immediate steps were taken by the Controller to change the duty runway, and VH-FST was to be the last aircraft to use the runway in question. The pilot later advised that as she flared the aircraft for landing, all forward visibility was lost because of sun glare. The aircraft touched down heavily and bounced several times, causing the nosegear to collapse. Although affected by the sun glare, the pilot had decided to continue with the landing, as she had not previously attempted a go around in conditions of limited forward visibility. The Tower Controller had been unaware of the sun glare hazard until the problem had been identified by the pilot of a landing aircraft.

During the landing roll the aircraft suddenly veered to the left. The pilot took corrective action but the nose gear collapsed and the nose section of the aircraft struck the strip surface. Although the strip was in regular use it was not being inspected. It was constructed on a dry lake-bed and the combination of no rain and regular use caused a soft patch to develop about 430 metres from the threshold. When the aircraft entered this area the nosewheel progressively turned left until it reached the stop. The sideload now imposed was too great and caused the noseleg bearing to fail.