Circumstances:

The helicopter was flying between two and three hundred feet above ground level when the pilot noticed severe oscillations of the rotor system, followed by engine stoppage a short time later. During the subsequent forced landing, the right skid contacted the ground at a significant forward speed and the helicopter rolled on to its right side. Examination of the rotor system indicated no apparent faults or failures prior to the accident. Fuel was drained from the fuel tank and the two carburettors (three points). The fuel tank and left carburettor showed clean fuel but the right carburettor contained a small but significant quantity of dirty water and solid debris. The fuel was also discoloured to a grey tone. The quantity of water was sufficient to cause engine rough running (which would induce rotor system oscillation) and engine stoppage. The pilot reported that he had conducted fuel checks before the flight from two drain points, one for the main fuel tank and one for the carburettors, both accessible from the left side of the helicopter. He was not aware that each carburettor had its own drain valve and that there was a total of three drain points.

Significant Factors:

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

1. The pilot was not aware of all the fuel drain points on the helicopter.

2. The engine failed due to water in a carburettor.

3. The pilot misjudged height and speed during the forced landing.

The pilot was undergoing a routine currency check with a flying instructor. As part of the check the pilot was asked to carry out a hover taxiing autorotation. The power was reduced to flight idle with the aircraft about 5 feet above ground level and moving forward at taxiing speed. The pilot carried out what was considered to be a normal landing, however, shortly after touchdown a loud bang was heard and the tail rotor and stabiliser were seen to land in front of the aircraft. The tailboom had been severed by the mainrotor during the landing. Indentations left by the skids in the soft ground indicated that the aircraft moved forward about 4 metres after initial ground contact. The main rotor was found to have an excessive static droop angle which reduced main rotor tip clearance from the tailboom by approximately 75 millimetres. This, in combination with attitude changes during the touchdown on the soft surface, rotor tilt and reduced rotor RPM, was contributory to the development of the accident.

A Distress Phase was declared by the Brisbane Senior Operations Controller when an Emergency Locator Beacon (ELB) signal was received by an overflying aircraft, in the Tiaro area, at 2242 hours EST on 31 May 1989. A search the following morning located VH-KAU. The pilot of VH-KAU stated that during a spray run, the engine failed completely when the helicopter was about 5 to 8 feet above ground level. During the subsequent autorotation onto the hillside the mainrotor contacted the tailboom. The pilot stated that he had subsequently drained the fuel system and found evidence of water contamination in the fuel. The engine was being operated on diesoline which was not a recommended fuel. The main rotor head showed evidence of a large pre-existing crack near the hub, and this item is subject to further investigation.

Circumstances:

The pilot flew alongside a vehicle travelling along a gravel road. The two occupants of the vehicle knew the pilot well and they were not surprised to see the aircraft. The aircraft was then flown across the road in front of the vehicle at an approximate height of 250 feet. Whilst continuing their progress along the road, the occupants observed the aircraft perform a "wing over" manoeuvre. The aircraft failed to recover from the resultant steep dive, striking the ground at approximately 65 degrees nose down. The two occupants of the vehicle extracted the pilot from the crushed cabin. Detailed examination of the wreckage failed to reveal any abnormalities.

Significant Factors:

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

1. The pilot performed an aerobatic manoeuvre at a low height.

2. In all probability, the pilot inadvertently flew the aircraft into a high-speed aerodynamic stall from which he was unable to recover in the height available.

Circumstances:

Approximately 30 minutes into the flight, the pilot realised that the aircraft performance was less than expected. The pilot and passenger then observed the landing gear had not fully retracted and was in a trailing position. Upon arrival at the destination, several unsuccessful recycles were attempted and low-level passes made for inspection purposes. Further unsuccessful attempts were made to extend and/or retract the landing gear. The aircraft made an approach with the landing gear trailing. During the landing flare, the landing gear folded into the retract positions and the aircraft settled firmly onto the grass flight strip. The investigation concluded that a metal saddle supporting the landing gear hydraulic lines had worn loose. A section of that line had then become chafed from contacting the main landing gear assembly during extension/retraction cycles. Eventually the line fractured, resulting in loss of hydraulic fluid. Subsequent attempts to recycle the landing gear depleted the hydraulic reservoir, leaving the landing gear in the trailing position.

Significant Factors:

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

1. Hydraulic line saddle became loose in service.

2. Operation of the landing gear subsequently chafed the hydraulic circuit.

3. The landing gear was unable to be extended or retracted following failure of the landing gear hydraulic circuit.

The pilot was reported to be conducting the third of a series of solo circuits. Approach and roundout were normal and the pilot intended to wheel the aircraft on. The aircraft bounced twice so the pilot applied full power and raised the nose in order to go around. The left wing stalled and the aircraft turned left rapidly. On the next touchdown the right landing gear was torn off and the propeller and fuselage pod were damaged.

At the conclusion of a mustering operation, the pilot flew to a neighboring property. He made an approach to a line of the houses at the property but no-one came out to meet the helicopter. He then decided to hover-taxy to a shed some 90 metres away and land. Whilst taxying the helicopter at about 10 knots, the pilot suddenly noticed a three phase power line immediately in front of him, angled at about 30` to his track. He attempted to avoid a collision by initiating a back-up but the mainrotor mast and tailrotor became entangled in the three wires. The bubble was smashed by a flailing wire as the helicopter descended out of control. The ensuing landing was heavy, resulting in a collapsed left skid gear. The helicopter remained substantially upright. The pilot later said that the power poles supporting the span were obscured by trees.

Circumstances:

The pilot arrived at his destination and initiated a normal circuit prior to landing. After partially completing his downwind checks, and before he lowered the landing gear, the pilot decided to conduct a quick inspection of the property for flood damage. On returning for landing, the pilot did not make any further pre-landing checks and the aircraft touched down with the landing gear retracted. A pre-recovery inspection did not reveal any defects that would have prevented the landing gear extending had it been activated. The pilot reported that he had minimum flying currency.

Significant Factors:

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

1. The pilot had minimum flying currency.

2. The pilot interrupted his landing checks, and he did not re-start the checks when he joined the circuit the second time.

3. The pilot failed to extend the landing gear prior to landing. This accident was not the subject of an on-scene investigation.

The pilot had completed one circuit involving a touch and go landing and a go around from the second approach. Following the third approach the aircraft touched down then veered to the left as it commenced the landing roll. The pilot was able to arrest the left swing as the aircraft reached the left side of the runway but a swing to the right then developed and resulted in a ground loop. The left main landing gear collapsed and the left wing impacted the ground. The investigation revealed that the pilot had used an incorrect crosswind control technique and then failed to maintain directional control during the landing roll. There were no pre-existing defects with the aircraft which could have contributed to the accident.

Circumstances:

During the pre-landing checks the right main and nose gear gave normal green light "gear-down" indications. The left main gear green light remained extinguished, and the red gear warning light illuminated. The instructor took over control of the aircraft and proceeded to carry out the emergency procedures, including recycling of the landing gear selector. Selection of "gear-up" resulted in no change to the position indicators, and no audible indication of the landing gear moving up. When power was reduced, the audible warning for "gear not locked" was heard. The emergency extension procedure was then carried out but was also unsuccessful. A number of low passes were carried out under the observation of ground engineers who reported that the left gear appeared to be not fully down. Yawing and "g" manoeuvres failed to lock the gear down. During the subsequent landing roll the left main gear collapsed, the aircraft swung to the left and departed the runway. At this point, the right main gear also collapsed. The failure of the normal landing gear extension system was attributed to lack of hydraulic pressure but the reason for this was not determined. The failure of the emergency landing gear system was the result of a binding down lock assembly which did not allow the lock to fully engage. The landing gear balance spring was too weak to pull the left leg over centre. Subsequent receipt from the manufacturer of new springs of different tension is considered to have solved the problem. This accident was not the subject of an on-scene investigation.

Significant Factors:

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

1. The main landing gear failed to extend due to lack of hydraulic pressure for reasons which were not established.

2. The Emergency landing gear lowering system failed due to weak balance spring tension.