A road accident victim required urgent transport to a hospital offering specialist facilities for her particular condition. Road transport by a suitably equipped intensive-care ambulance was not available, and a decision was taken to employ a helicopter. When first contacted, the pilot expressed doubt about the feasibility of using the helicopter because of adverse weather conditions in the area. Some 30 minutes later the pilot was again contacted and requested to undertake the flight. He agreed, subject to weather conditions being suitable, and prepared for the flight from Wollongong to the hospital at Bowral where the patient was being held pending transfer to Sydney. The pilot, accompanied by a crewman and a paramedic, departed Wollongong at 0027 hours local time. As the aircraft approached Bowral, deteriorating weather conditions were encountered. Arrangements were then made through the ambulance radio network for the patient to be transported to Wilton, where the pilot landed shortly after 0100 hours. The patient arrived about 20 minutes later and DEPARTURE for Sydney was made at 0153 hours. When the pilot contacted Sydney Flight Service he was advised that the Control Zone was closed to visual operations because of low cloud. The paramedic considered that the flight should continue because of the patient's condition, and the pilot declared a mercy flight. He was cleared to continue on an emergency basis, with radar directions being provided to assist navigation. The reported cloud base at Sydney Airport was 300 feet, and the night was dark, with no moon. At 0212 hours the pilot reported that the aircraft was running into cloud, and he would hold over Parramatta. No further transmissions were received from the aircraft. Shortly afterwards it was discovered that the aircraft had crashed on the tidal embankment of the Parramatta River. A subsequent detailed examination of the wreckage revealed no mechanical defect or malfunction which might have made an accident inevitable. It was considered that the accident probably resulted from a loss of control of the helicopter during a turn away from an area of low cloud. Neither the aircraft nor the pilot was approved for flight in other than visual conditions, and the pilot probably became disoriented either from the loss of the visible horizon, or by reference to a false horizon. It was evident that he was in the process of regaining control, but insufficient height was available to complete the recovery before impact with the ground.

Circumstances:

During preflight inspection, the pilot visually checked that both fuel tanks were full. About two hours after DEPARTURE, whilst cruising at 7000 feet, the engine suffered a sudden and total loss of power. The pilot immediately selected the left fuel tank but was unable to restore power. As both fuel contents gauges were indicating above half, the pilot reselected the right fuel tank and unsuccessfully continued attempts to restart the engine. The aircraft was force-landed in a swamp, coming to rest intact, but partially submerged. The occupants were able to escape onto the right wing and were rescued by helicopter a short time later. Investigation revealed the right fuel tank cap was unfastened and the tank contained only one litre of fuel. Although the left tank cap was partially unlocked, the tank opening was sealed. That tank contained about 65 litres of fuel. The locking mechanism on both tank caps was extremely stiff and difficult to operate. The unfastened right fuel tank cap had allowed most of the fuel to vent from the tank opening during flight. The engine, which was operating from the right tank, lost power when all fuel was exhausted from the tank. The venting action also caused the bottom of the fuel cell to rise, biasing the fuel contents gauge to indicate about half full. It is believed the engine did not restart with the left tank selected because the pilot did not allow sufficient time for air to be purged from the engine fuel injection system.

Significant Factors:

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

1. Both fuel tank caps were extremely difficult to lock closed.

2. The preflight inspection was inadequate and both fuel caps were not correctly locked before flight.

3. Fuel was lost from the right tank in flight.

4. The right fuel gauge incorrectly indicated the quantity of fuel in the right tank.

5. The engine lost power due to fuel starvation.

The helicopter was being used to film a tourist promotion advertisement. The film to be taken involved horse riders on a trail ride, along a ridgeline, backlit by the late afternoon sun. A ground survey of the area had been completed about ten weeks earlier by the pilot and production film crew. Before commencing the filming the film crew completed another ground survey of the area and also an aerial survey in the helicopter. To facilitate the filming a wooden platform was fitted to the landing skids to carry the cameraman and his equipment. The filming runs were flown in a north-westerly direction parallel to the main power line running through the area. Initially the runs were carried out to the east of the power line but subsequently runs were completed to the west of the line. All runs were flown at heights varying between 10 feet and 100 feet agl. During the last filming run the skids struck the two cables of a spur which ran from the main power line at an angle of 92 degrees. The helicopter pitched nose down and struck the ground in a near vertical attitude. On impact the landing skids, platform and cameraman were thrown clear of the main wreckage. Fire broke out immediately and only the pilot survived the combined effects of impact and fire.

The wreckage was completely burnt out. The spur line was strung across a gully over which the helicopter had been flying on the filming runs. The distance between the main line and the first pole on the spur line was 529 m and the line was struck at a point 45 ft agl. Because of the dull grey-brown appearance of the countryside no contrast was provided for the spur line. The filming runs were being made into the late afternoon sun and the pilot and film crew were unaware of the presence of the spur line.

Circumstances:

The flight was scheduled as the last in a series for the pilot under instruction to gain an endorsement on twin engined aircraft. The instructor occupied the right hand cockpit seat and handled the radio communications. He used a handheld microphone which produced transmissions which were scratchy and somewhat garbled. Also, his speech delivery rate was rapid. The Runway 28 Right circuit pattern was relatively busy at the time with both circuit and departing traffic. Examination of the Air Traffic Services communications tape in the period leading to the accident showed that the Tower Controller asked the pilot how many more circuits he intended to fly. The instructor responded that the next circuit would be his last and that it would be a "fully feathered full stop" (This phrase was indistinct and could not be understood from the tape until it had been replayed a number of times). During the final circuit, the instructor reported mid-downwind, adding "just confirming (.......) feathered landing" The Tower Controller asked the pilot to repeat the message, to which the response was "we just have one feathered" Again the phrase was difficult to understand and the reply by the Tower Controller referred to the previously crowded circuit. This out of context response was not queried by the instructor. On final approach with the pilot-under-instruction flying the aircraft, the right propeller feathered, and approaching the briefed committal height of 400 feet, a preceding aircraft was observed to be still on the runway. The approach was continued and full flap selected as both pilots thought that the other aircraft would clear the runway for their landing. At a height of about 300 feet, however, the Tower Controller instructed VH-UAU to go-around. The instructor took control of the aircraft and continued the approach, but the Tower Controller repeated the go-around instruction. The instructor then applied full power on the left engine and told the pilot under instruction to start the right engine. By this stage, the aircraft had descended to about 100 feet above ground level. It overflew the aircraft on the runway and continued a slow descent until it struck trees and spun into the ground about one kilometre beyond the end of the runway. No attempt was made to retract the landing gear and flaps. The instructor said that after hearing the first go-around instruction, he had intended to land beyond the aircraft on the runway but decided there was insufficient runway remaining for such a course of action. He then attempted to reach a clear area beyond the airfield boundary, but the aircraft struck the trees prior to this. The investigation established that the Tower Controller was not aware that VH-UAU had one propeller feathered until the stationary propeller was sighted after the second go-around instruction was given. Because the advice from the instructor concerning the feathered propeller was transmitted as an "add-on" to standard radio phraseology, there was no direct means of him knowing whether or not his intentions had been understood by the Tower Controller.

Significant Factors:

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

1. Radio transmissions from the aircraft were of poor quality.

2. The Tower Controller was not aware that the aircraft was operating with one propeller feathered.

3. The approach was continued below the briefed committal height without a landing clearance having been issued and with the runway occupied by another aircraft.

4. An attempt was made to restart the right engine, however, no attempt was made to retract the landing gear and flaps.

Recommendations:

There is no operational difference between flying with one engine shut down for training purposes and a genuine engine failure. In the latter case, the aircraft is given priority in the landing sequence by air traffic control. There is justification, therefore, for some formal procedure whereby the practice of shutting down an engine in the circuit for training purposes is conditional upon a separate clearance from the tower controller. The recommendation is made that the Civil Aviation Authority give consideration to amending procedures to the effect that aircraft require a formal clearance for practice engine shutdown exercises in circuit traffic patterns.

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.