The pilot had flown the helicopter from Darwin to Jabiru, carried out some local flying at Jabiru and then returned to Darwin on the day of the accident. As the helicopter was approaching Darwin the pilot was instructed by an air traffic controller to hold position in the Palmerston area and await further clearance. Shortly afterwards the engine stopped, and the pilot was forced to complete an autorotational landing. The pilot misjudged the approach, and the aircraft landed heavily.

The pilot did not complete a flight plan prior to the flight and no evidence was found to indicate she used any form of formal fuel management to ensure that fuel available met the required reserves.

The aircrafts total fuel capacity of 200 L provided for an endurance of approximately 2.6 hours at a normal fuel consumption rate of 75 L/hour. The flight to Jabiru took 2.5 hours. A total of 194 L of fuel was required to fill the tanks following this flight. The tanks were also refilled following the local flying. Although almost all the fuel had been exhausted on the flight to Jabiru the pilot departed for the 2.5 hour flight to Darwin without having made any alternative fuel arrangements. The fact that the aircraft had almost run out of fuel on the flight to Jabiru did not register.

When the pilot was instructed to hold position in the Palmerston area and await a further clearance she advised the controller that the aircraft was low on fuel but she did not communicate any urgency about the situation. Ten minutes later, whilst still in a holding pattern, the engine stopped as a result of fuel exhaustion. The helicopter had been airborne for 2.6 hours when the engine stopped.

The pilots actions indicate she was never sufficiently aware of the aircraft's fuel situation. The lack of planning and the failure to use a formal management procedure probably exacerbated the situation.

The pilot initiated normal gear selection after arriving in the circuit area at Manilya. The gear extension process stopped after the nosewheel and right main gear had extended. The pilot checked the circuit breakers and recycled the gear twice more with the same result.

The pilot decided to return to Carnarvon where the gear could be inspected visually. Observations by a pilot and engineer confirmed that the left main gear was up. Use of the manual extension system and the introduction of 'g' forces were unsuccessful in causing the left main gear to extend.

After discussion with engineers in Carnarvon and Perth the pilot elected to carry out a wheels up landing on the grass flight strip beside sealed runway 18. The landing was successful.

An inspection of the landing gear systems disclosed that the hinge bolt, from the front hinge of the left landing gear door, was missing. The missing bolt allowed the landing gear door to twist, in the airflow, jamming the door closed and preventing the left gear from extending.

The missing bolt was not recovered. A number of landing gear hinge bolt nuts, including one that was adjacent to the hole left by the missing bolt, were recovered from the channel surrounding the landing gear bays on both sides of the aircraft. It was not possible to determine if any of the nuts came from the missing bolt. There was no evidence of stress, in the area of the missing hinge bolt, to indicate that the bolt had been working prior to its loss.

The landing gear doors had been removed, inspected for cracking, and replaced eight flying hours prior to the accident. The gear had been extended and retracted a number of times, without apparent problems, after the replacement and prior to the final flight. The failure sequence indicates that the bolt was probably in place for a period following the maintenance and fell out on the accident flight. No history of problems with the hinge bolts was disclosed during the investigation.

It was not possible to determine whether the bolt failed and fell out, as a result of fatigue or overload, or if it was incorrectly fitted following the maintenance conducted shortly before the accident flight. There was some evidence that the engineer responsible for re-fitting the suspect bolt was distracted by a personal problem during that process however he did not recall any specific event that may have contributed to the loss of the bolt.

The pilot reported that during the approach the airspeed was too high. He decided not to go around as the tall trees surrounding the strip made it look restricted. He flew the aircraft straight and level to wash off airspeed and felt he could still land and stop before the end of the runway.

On touchdown the aircraft ballooned. The pilot recovered to fly the aircraft parallel to the runway but did not add power, to overcome the ballooning effect, as he felt he would run short of runway. On the second touchdown the aircraft bounced and on the third touchdown the nosewheel collapsed. The aircraft skidded to a halt towards the left side of the runway.

The accident sequence was typical of other accidents where the runway perspective appears different to that previously experienced by the pilot. The perspective can be altered by a narrower than usual runway for its length and/or by the surrounding terrain or foliage.

The pilot was landing on the westerly strip at McCaffrey Field with 10 knots of wind from the north (all cross wind). During the round out for landing, the aircraft ballooned, and the pilot pushed the nose down and at the same time retracted the air brakes. The aircraft struck the ground in a nose down attitude and bounced. It then veered left under the influence of the cross wind and bounced again, before running into the boundary fence.

During climb to cruise, passing 7,500 ft, the ground proximity warning system sounded as the aircraft encountered moderate rain and light hail. There were storm cells on either side of track.

Post flight inspection revealed hail damage to all leading edges, right landing light cover, and radome.

The ground proximity warning system often gives a false alarm when it encounters precipitation (heavy rain and/or hail). This is a known deficiency against which there is no technological defence.

The pilot had remained clear of the storm cells by using his airborne radar. It is a known phenomena that hail can fall well outside its associated storm cells.

Sequence of Events

The instructor pilot said that his student had completed four dual circuits with very satisfactory landings off each approach. During the fifth approach, the student flared the aircraft too high and before the instructor could take control, it stalled and struck the ground in a heavy landing.

The left main gear collapsed, and the aircraft came to rest on its bent nose gear and left-wing tip.

Analysis

The instructor was unprepared for the high round out following the student's good landing performance on the previous occasions. He did not take control in time to prevent a heavy landing.

Whilst on descent through about FL240 with C autopilot engaged, the aircraft rolled rapidly to the right but immediately corrected itself. Speed brakes were extended at the time.

Flight Data Recorder information did not reveal any unusual flight control inputs, however individual spoiler positions are not recorded, only the speed brake control handle position is recorded. A ground functional test of the flight control system was normal, but a loose electrical connector at number 6 spoiler (left wing) power control actuator was found. It is considered that the loose connection may have commanded the spoiler to retract, causing a roll to the right which was corrected by the autopilot.

The operator has instigated a fleetwide check of spoiler electrical connections.

The pilot was conducting a landing on a grass strip. During the landing roll the glider overran the strip end and struck a wire perimeter fence.

A report by the Gliding Federation of Australia indicated that the pilot did not compensate for the prevailing wind when executing the approach.

The pilot had initially planned to land to the north on a strip which was about 950 metres long. When he saw that a formation flight was preparing for a take-off to the west on the 400-metre strip, he decided land to the west. The wind was a light north westerly. He reported that his aircraft touched down near the 270 threshold at 60 knots with full flaps and then bounced a couple of times before he attempted a go-around. The local chief flying instructor (CFI) witnessed the accident from one of the formation aircraft and said that the aircraft looked to be faster on touchdown, more like 65 knots.

During the attempted go-around, the pilot selected flaps fully up and full power but almost ran out of strip before becoming airborne. While attempting to avoid a tree near the end of the strip, he stalled the aircraft which then settled onto a fence.

The CFI believed that the go-around would have been successful if the pilot had selected the flaps up in stages rather than going from full flap to zero flap while attempting to become airborne in a short distance.

The pilot reported that the flight departed from an agricultural strip located in a valley surrounded by hills. The aircraft carried a full load of superphosphate to be spread on a property approximately one mile from the strip. The pilot had previously surveyed the property and the flight path. He had selected a route that took him up through a valley between hills and then over a low ridge to the property.

After take-off the pilot set climb power and selected climb flap in order to follow his predetermined route to the property. The pilot advised that as the aircraft flew towards the low ridge it appeared to be descending rather than climbing. He elected to carry out a partial dump and to apply extra flap to clear a clump of trees. The speed deteriorated to 60 knots from the initial climb speed of 70 knots. The pilot did not increase power.

Some 300 metres later another partial dump was carried out to clear another tree. As that tree was cleared the pilot again initiated a partial dump and turned to the right in an endeavour to escape from a rapidly deteriorating situation. Immediately the turn was initiated the right wing dropped and the aircraft stalled, impacting the ground onto the right wing and cartwheeled to a stop some 50 metres from the initial impact.

The company chief pilot examined the accident site and advised that the flight path through the valley was in a classic false horizon situation whereby the surrounding hills caused the pilot to consider that the flight path was over flat terrain whilst in reality the terrain was rising approximately 5 degrees up to the ridge. The chief pilot also advised that the aircraft would not have been able to outclimb the terrain at high gross weight with only cruise power set.

Examination of the wreckage did not disclose any pre-impact factors that may have contributed to the accident. Weather and pilot workload were not considered to be factors in this accident.

The pilot had flown approximately 1200 hours on agricultural operations and 244 hours on the type. His loss of situational awareness could be due in part to his relatively low experience.

Significant factors

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

(1) At high weight, and with climb power applied, the pilot flew the aircraft on an inappropriate flight path into rising terrain.

(2) The pilot did not take appropriate remedial actions when the aircraft could not outclimb the terrain and the aircraft speed deteriorated.

(3) The pilot lost control of the aircraft while attempting a turn at low speed.