VH-LHD was on a flight from Sydney to Gunnedah and had commenced descent from 10,000ft. The pilot was advised by Flight Service that there was no Instrument Flight Rules [IFR] traffic which was the correct information at that moment. Immediately after this transmission information was received by the Flight Service Officer on VH-ASO [Mooney 20J] departing Tamworth on climb to 6,000ft on a track that conflicted with VH-LHD.

The Flight Service Officer [FSO] was performing co-ordination tasks at the time and did not immediately recognise the confliction, preferring to complete these tasks before assessing the changes due to the presence of VH-LHD. As soon as the FSO realised the situation, traffic information was passed to both pilots but as these transmissions were taking place the aircraft passed with approximately 500ft vertical separation and no horizontal separation with the top aircraft VH-LHD descending.

Significant Factor

• The Flight Service Officer did not realise the implications of the departure of VH-ASO in sufficient time to alert the pilots to the conflict.

The search and rescue helicopter was called out to a potential rescue and medical retrieval of a man who had fallen from a waterfall at Barrington Tops which is a mountainous/wilderness area. Due to extensive cloud cover, approaching last light and a lack of contact with ground personnel, the pilot-in-command elected to land near Barrington Guest House. 900 metres south-east of the guest house was a paddock apparently suitable as a helipad.

While flying a right downwind leg at about 60 knots and 500 feet in very light drizzle, the pilot and crew/passengers searched for powerlines and other potential obstructions. Powerlines parallelling the intended landing direction were seen. One of the crewmen searched for wires by looking out through the only sliding door fitted, which was on the left side of the helicopter. A normal approach was flown. When the helicopter was about 20 knots and 25 feet above the ground, the crewman sitting in the left front seat suddenly detected a spur line running across the approach path. He called out a warning to the pilot, but it was too late. The helicopter struck two wires. The pilot immediately lowered the collective in an attempt to land as soon as possible. The landing was heavy. The helicopter impacted the ground in a slightly nose down attitude while banked slightly to the left.

The wire strike was at the level of the rotating swashplate. Cyclic control was probably lost when the control rods above the swashplate were damaged by the wires.

The spur line was particularly difficult to see. Rising ground ahead of the wires, in the direction of landing, camouflaged the wires. The pole at the end of the spur line was somewhat hidden by trees and light drizzle reduced visibility.

A wire strike protection device was not fitted on the helicopter.

SIGNIFICANT FACTORS 

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

1. The powerline was particularly difficult to see because of its location, the surrounding terrain and foliage.

2. Visibility was reduced due to light drizzle.

The student pilot had been authorised to carry out a period of solo revision in the training area. The Automatic Terminal Information Service (ATIS) for departure from Bankstown was "Information India", wind 040/08, visibility 10 kilometres or greater, cloud 3 Octas strato-cumulus at 3000 feet. When reporting inbound to Bankstown, the pilot advised having copied "Information India" and was told to expect a straight in approach for runway 11 Left. Soon after, the ATIS was changed to "Juliet". The pilot reported that he checked the windsock at 300 feet on final but detected no indication of a crosswind component and continued the approach. The aircraft subsequently touched down heavily on the nosewheel, collapsing the nose landing gear. The change in the ATIS indicated an increase in the crosswind component from 8 kts or less to 12-16 kts. The accident was consistent with the pilot using an inappropriate landing technique for the prevailing conditions. The pilot said he was aware that the ATIS had changed but did not copy the amended information.

The purpose of the flight was to complete the training for an aircraft endorsement. Two circuits were flown after the initial take-off, during which all radio communication equipment progressively failed. No alternator failure light was observed. When the landing gear was finally selected down neither the instructor or the trainee could determine if the landing gear had correctly extended. They assumed it had extended however as the landing gear warning horn did not sound when the throttle was retarded. The aircraft subsequently landed with the landing gear retracted. No fault could be found with the landing gear or radio systems after the accident. The reason for the apparent loss of electrical power could not be established.

During approach the pilot was distracted by the proximity of trees and wires near the threshold. He allowed the speed to deteriorate and an excessive rate of descent to develop which he did not arrest. The aircraft landed heavily dislodging the nose wheel. The nose wheel mount tube dug into the surface of the strip and the aircraft overturned. The two occupants escaped without injury.

Significant Factors

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

1. The pilot was not aware of the degrading airspeed, possibly due to channelised attention.

2. The aircraft developed a high rate of descent.

3. The pilot did not arrest the high rate of descent.

4. The aircraft landed heavily and the nosewheel broke off.

During the procedure turn at the end of a spray run the engine power failed. During the ensuing forced landing the pilot had to overpitch the rotor to avoid power lines. The helicopter landed heavily fracturing the tail boom, damaging the main rotor blades, and collapsing the skids.

Inspection of the engine disclosed that the left exhaust pipe had fractured inside the carburettor heat shroud. The exhaust gases were then ingested by the engine with consequent total loss of power.

The exhaust pipe fracture was caused by fatigue occasioned by the unsupported nature of the installation. The shroud would have masked the fracture growth, which was not in evidence at the last inspection some 40 hours prior to failure.

Significant Factors

1. The engine power failed due to a fractured exhaust pipe.

2. The pilot was forced to overpitch to avoid obstructions.

3. The helicopter landed heavily.

Following a normal take-off, the wing leading edge slats locked in the down position when the crew selected flaps up.

The aircraft returned for a safe landing some five minutes later.

Engineering investigation revealed a failure in the slat asymmetry pick-up unit had caused the slats to lock on retraction.

The aircraft was being employed as a tug to launch gliders. On this occasion, the tug, with the glider in tow, commenced take-off with a crosswind from the right of about 10-15 knots.

Before the tug reached flying speed it began to veer left. The pilot was unable to correct the swing and the glider, which was now airborne, released the tow. The tug ground looped to the left, dislodging the right main landing gear and damaging the right wing and nose cowl. The glider landed on the runway without further incident.

The pilot had commenced a take-off from a low hover when the helicopter nosed up sharply. He lowered the collective pitch lever and opened the throttle, suspecting over-pitching as the cause. The helicopter struck the ground in a slightly nose low attitude with the right hand skid while moving forwards and to the right. The skid separated and the helicopter cartwheeled forwards before coming to rest on its right side.

A bellcrank from the cyclic control system of the helicopter was found fractured after the accident. Metallurgical analysis of the part found that the failure was caused by impact forces experienced during the accident sequence.

The reason for the loss of pitch control was not determined.

The aircraft was landed heavily resulting in the separation of the right-hand brake calliper. The pilot lost directional control of the aircraft, and it veered off the runway and ground looped, causing damage to the ailerons, wingtips and the interplane struts.