As the aircraft was climbing through 1000 feet the pilot noticed a reduction in manifold pressure and fuel flow readings for the right engine. He advanced the right throttle and found that the engine instruments indicated that the engine was performing as if it was normally aspirated. A short time later he saw flames coming from the right engine and the fire warning light and alarm bell activated. The fuel to the engine was shut off but the pilot was unable to feather the propeller. The fire did not go out. However, the pilot was able to successfully land the aircraft at Rockhampton where the fire was extinguished. An inspection of the aircraft revealed that the number 4 cylinder was cracked and holed around the seat of the exhaust valve. It is considered that the cylinder cracking and the subsequent burn away of material resulted from extreme operating temperatures. The torching of the combustion products through the hole resulted in the induction manifold being consumed by fire. It was also determined that the propeller could not be feathered because the propeller governor control cable had become inoperative after its mount point on the induction manifold had been destroyed by fire.

Circumstances:

The cameraman was filming a car from the right rear side of the helicopter which had the door removed. The car was travelling north-west at about 60 km per hour along a quiet country road through very open terrain. The helicopter flew at about 30 feet above the ground and about 100 metres from the left rear of the car. During the first filming run the pilot noticed a school bus driving north towards a "T" intersection through which the car would pass. He decided to avoid flying low over the bus and to remain well clear of a house just beyond the intersection. While distracted by the moving bus he veered from the planned flight path and pulled up over a powerline which followed the road used by the bus. The top strand of the powerline passed just over the front of the left landing skid, slid back to the cross tube, and began to drag the helicopter to the ground. While the pilot counteracted the inflight effects of being snagged by the powerline, the main rotor severed the tail boom, shortly before the helicopter impacted the ground. On impact the fuselage and cabin broke up, the fuel tank split, and the left landing gear separated but there was no fire. The pilot was experienced in the filming role and was familiar with the area. A strong, gusty, northerly wind caused mechanical turbulence, but conditions were suitable for filming.

Significant Factors:

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

1. The pilot was distracted by a moving school bus.

2. The pilot was on a filming task involving low level operations.

3. The pilot misjudged his altitude and clearance from the wire.

Recommendations:

The cameraman was wearing a sturdy "Parachute Australia" harness anchored to an approved, custom-built, airframe bracket. All restraints held but difficulty was experienced releasing the harness catches after the accident. The harness undoubtedly saved the cameraman from worse injury. The pilot believes that this harness and attachment system surpassed the average standard of similar equipment commonly used. It is recommended that the CAA gives consideration to formalizing a standard for crewman harnesses and their attachments to airframes.

Following an early morning flight to Bankstown and return to Sydney, the helicopter was being prepared for a further flight. The preflight inspection had proceeded to the point where one of the crew had untied the main rotor from the stowed fore and aft position and was rotating it to the abeam position. During this procedure a restriction was noticed in the main rotor travel. Investigation revealed the restriction was caused by a partial disconnection of the tail rotor drive shaft which allowed the drive shaft to foul the drive shaft cover assembly. One nut connecting the forward disc of the drive shaft was missing from its bolt, the other nut was only finger tight. One nut at the rear disc was only finger tight, the other nut/bolt assembly was completely detached. The self locking capability of the four nuts was found to be serviceable. The helicopter had only operated 12.5 hours since extensive maintenance had been carried out on the tail rotor drive assembly.

The pilot reported that he had obtained normal indications when he selected the landing gear down. The subsequent touchdown was normal but as the nosewheel was lowered to the ground, the nose gear leg collapsed. The eyebolt between the nose gear retract aft rod and the landing gear motor had failed, resulting in the nose gear failing to lock down and allowing it to retract on ground contact. The eyebolt had failed at the beginning of the thread, adjacent to the eye. Specialist examination indicated that the initial fracture was indicative of fatigue and had been present for some time. The aircraft had only recently been returned to service following an earlier accident which involved a fatigue failure of the nose gear retract rod plunger fork. It was considered likely that the fracture had initiated at the same time as the earlier failure.

On arrival at his destination, the pilot joined the circuit on the downwind leg and used the pitch lever to signal his arrival to the ground party. He then distracted himself by cancelling his SAR watch by radio. By this time he had flown past the windsock and it was no longer in view. This distraction continued while he tried to recall the wind direction and decide if he should go around and check the windsock. Deciding to continue the approach, he positioned the aircraft on final but only carried out his final approach checks in a perfunctory manner and did not positively check the gear down indications. The aircraft subsequently landed wheels up and neither the pilot nor the passengers recalled hearing the undercarriage warning horn sound.

Detailed investigation showed that the warning horn micro-switch actuator on the throttle assembly was defective and of a faulty design. The subject component had been redesigned by the manufacturer, however, the modified component still bore the same identification number as the superseded item. In addition, the component of faulty design was still available in the spares inventory.

Circumstances:

The aircraft was involved in local flying. On the final landing and during touchdown, the landing gear collapsed, and the aircraft slid to rest on the runway. The pilot advised that the landing gear selector switch had been accidentally bumped to the ‘UP' position by the knee of the front seat passenger. Inspection of the landing gear selector switch revealed that the plastic identification knob had been screwed too far onto the switch arm. This rendered the locking function of the switch ineffective.

Significant Factors:

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

1. Poor design of the plastic identification knob of the landing gear selector switch.

2. Screwing the plastic identification knob too far onto the landing gear selector switch rendered the locking function ineffective.

Recommendations:

1. That the Civil Aviation Authority publish an Airworthiness Advisory Circular article to advise maintenance personnel that the safety lock function of the landing gear selector, (as used in many general aviation aircraft) will be compromised if the plastic switch knob is screwed on too far.

2. That an article be published in the BASI journal to advise pilots of retractable landing gear general aviation aircraft, not to attempt to tighten the landing gear selector switch knob if it ever comes loose. This action may render the locking function inoperative, as it may only need one half turn for this to happen.

At about 300 feet on climb after take-off, the engine suffered a partial loss of power. The pilot turned the aircraft back towards the strip and shortly after aligning it for landing, the engine suffered a further loss of power. The pilot was unable to avoid power lines on the approach path and the aircraft collided with the wires before coming to rest near a house. The engine was still running when the aircraft struck the ground, and the reason for the decrease in performance could not be established.

The pilot was conducting his first solo flight in the aircraft type following a short dual check. During his return to Moorabbin he noted what he considered to be a radio failure. He was concerned because of approaching last light, and made a no-radio entry return to the aerodrome. He made two circuits during which he attempted to extend the gear and flaps using their normal, electrically powered, systems. Although unable to obtain a gear down indication and because he was of the opinion that the problem was related solely to the radios, he elected to land the aircraft without considering the use of the emergency gear extension system. The aircraft subsequently touched down with both gear and flap retracted. Investigation revealed that the aircraft battery was discharged. The pilot had not turned on the alternator field switch during the pre-start or pre-taxy checks. He was surprised to learn of the existence of the field switch when it was mentioned during the subsequent interview.

After landing, the pilot was taxying the aircraft along a marked taxyway between two hangars. Several aircraft were parked in the vicinity, and the pilot taxied at a slightly higher level than normal in order to reduce the effects of downwash. He suddenly noted cables just above eye level, and banked steeply to the left in an effort to avoid a collision. However, the main rotor blades struck and severed the cables, which were a pair of disused Telecom lines strung between the hangars, and both blades then struck the ground. The cables were not marked, and at the point where they crossed the taxyway they were 6.6 metres above the ground.

The pilot brought the helicopter to a hover at 1000 feet agl, pointing approximately into wind. The aircraft began to yaw to the right and the pilot was unable to stop the resulting rotation. The helicopter descended in a steep nose down attitude and struck the ground heavily while still rotating to the right. The landing skids were torn off and the helicopter came to rest on its left side. No mechanical fault or defect was found with the helicopter which might have contributed to the development of the accident. It was considered likely that the aircraft experienced the phenomenon known as "tail rotor breakaway", which results in an uncommanded yaw to the right accompanied by a steep nosedown pitch change. The pilot was aware of the phenomenon, and had read various articles on the subject. However, much of the information available at the time was of a confusing and conflicting nature, and the recovery action employed by the pilot on this occasion was ineffective.