The pilot reported that the take-off proceeded normally until the point of lift off, when the engine hesitated and lost power for about 3 seconds. Power was then regained, however the pilot was not certain whether full power was developed. He elected to abandon the take-off, but there was insufficient strip length remaining in which to safely stop the aircraft. He then reopened the throttle in an effort to clear a fence at the end of the strip and land in the adjoining paddock. The noseleg struck the fence, and the aircraft then ran through a ditch before coming to rest. The reason for the short term power loss could not be determined

The pilot had been authorised to carry out circuit and landing practice. He had been operating for about 20 minutes when witnesses observed that immediately after lift-off from a touch and go landing, the aircraft assumed a higher than normal nose attitude. At an height of between 100 and 150 feet above the runway, the engine noise ceased and the aircraft pitched forward to a steep nose down attitude. This attitude was maintained until the aircraft impacted the ground, before coming to rest 50 metres to the right of the runway centreline. A subsequent investigation determined that the pilot had probably suffered a heart attack at about the point of lift-off, resulting in incapacitation and loss of aircraft control.

The aircraft departed with a planned fuel endurance of 170 minutes, and an expected flight time of 116 minutes. About 110 minutes after take-off the engine lost power and the pilot was forced to land on unsuitable terrain. The aircraft sustained damage to the wings, landing gear and rear fuselage as it ran through two fences and came to rest after striking several trees. Initial inspection revealed that the spring loaded fuel drain cock for the right tank was in the open position. The aircraft was parked on wet grass when the pilot conducted the fuel drain check and he evidently did not visually check to ensure that the right wing drain cock had resealed. When the engine lost power the pilot switched the electric fuel pump on before changing tanks. This sequence is the reverse of that recommended by the manufacturer and increases the time taken to effectively restore power. Adequate fuel had remained in the other tank to allow completion of the flight, had engine power been regained.

The pilot was landing on a property strip in gusty crosswind conditions. Directional control was lost during the landing roll and the pilot was unable to prevent the aircraft from running off the side of the strip. As he attempted to taxi the aircraft back onto the strip the nosewheel entered an area of soft sand and subsequently collapsed. The particular strip in use was only 20 metres wide, and consequently did not meet the requirements for an Authorised Landing Area. The strength of the crosswind component could not be determined.

During climb, at about 2500 feet, a loud noise was heard from the engine coincident with a power loss and severe vibration. The choice of suitable forced landing areas was restricted by the strong wind and the terrain features. The aircraft touched down 188 metres from a fence and levee banks either side of a narrow irrigation channel. An attempt to avoid the fence and levee banks by overflying to an adjacent paddock was unsuccessful because of low airspeed. The aircraft collided with the levee, catapulted over the channel and came to rest 15 metres beyond. It was determined that the loss of power was due to a spark plug, complete with heli-coil, becoming dislodged from the Number 1 cylinder. The cylinder had been installed on the engine 7 flying hours previously, after being repaired by an approved organization. The most probable cause of the defect was overtorquing of the spark plug during installation, thereby damaging the tapped alloy of the cylinder into which the heli-coil had been screwed. With this thread damaged, the spark plug was able to vibrate to further damage the alloy thread. Exhaust gas escaping between the tapped thread and the heli-coil accelerated the damage process until eventually the spark plug was ejected by engine combustion pressures.

The purpose of the flight was to allow the passenger to decide whether he would undertake flying training on ultralight aircraft. After take-off, the pilot flew the aircraft along the coast to the north of the DEPARTURE strip, before returning by the same route. Approaching Moonee Beach the pilot climbed the aircraft to about 500 feet over the water. The aircraft then entered a wing-over type of manoeuvre, followed by a steep dive to a height of about 150 feet above the sea. A pull-out was made but as the aircraft climbed steeply the left wing failed and folded back against the fuselage. The pilot attempted unsuccessfully to deploy the emergency parachute and the aircraft fell into the sea about 30 metres from shore. The passenger was able to release his harness as the aircraft sank, and after trying for some time to locate the pilot in the wreckage he swam to the beach. The body of the pilot was recovered the following day. A detailed examination of the wreckage revealed no evidence of any pre-existing defect that might have contributed to the accident. It was evident that the steep dive and subsequent pull-out manoeuvre had exceeded the structural limits of the aircraft design.

The pilot was to conduct two spot landings from practice forced landing approaches commenced at 2000 feet. On the first approach an undershoot developed and power was used to complete the landing. The second approach was high and touchdown was made about half way down the 730 metre strip. A go-around was initiated but the engine failed to develop significant power. The take-off was then abandoned and the aircraft struck a dirt bank and drain beyond the end of the strip. It is probable that carburettor icing caused the lack of engine response when the go-around was initiated. Braking was inhibited by wet grass covering the remainder of the strip available.

Circumstances:

The aircraft was landing downwind on an agricultural strip. During the landing roll the aircraft departed the left side of the strip following the failure of the right brake coming to rest inverted in a rice paddy. The investigation found the right brake master cylinder had buckled in the reservoir area. The buckling and resultant misalignment of the piston rod caused a bending failure of the rod and liberation of the piston with a subsequent loss of hydraulic pressure to the right brake. The reason for the failure of the master cylinder was not determined. There are no other recorded accidents involving master cylinder failures in this type of aircraft. The failure is therefore considered an isolated case.

Significant Factors:

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

1. Material failure of the right brake master cylinder piston rod.

2. Loss of hydraulic pressure to the right brake.

3. The pilot was unable to maintain directional control on the landing roll.

Circumstances:

The aircraft operator employed two Navajo aircraft on regular crew changes at oil exploration sites. On the previous day one of these aircraft had become unserviceable at Cunnamulla. The operator had then hired VH-EDL to pick up the next day's work. This aircraft was to be flown to Cunnamulla by an engineer who would repair the faulty aircraft and return to Archerfield in that aircraft. One of the operator's pilots would then accept the replacement aircraft and continue the charter to Jackson. This pilot had not flown the replacement aircraft previously. At Cunnamulla, the two pilots discussed the fuel quantity in VH-EDL which they agreed was adequate for the flight to Jackson. The fuel quantity could not be checked visually, due to wing dihedral. The aircraft was not fuelled at Cunnamulla as indicated on the flight plan. During the flight to Jackson the pilot became increasingly concerned about the fuel state of the aircraft. He selected the auxiliary tanks but noticed that the gauges were indicating empty and assumed that these tanks were empty. The pilot then reselected the main tanks as his employer did not favour allowing the tanks to be run dry due to passenger considerations. The pilot considered diverting to an alternate strip but decided to continue to Jackson. At about 1400 feet above ground level and three kilometres from the Jackson strip the left engine began to surge and then stopped. Shortly afterwards, the other engine stopped. The pilot elected to land the aircraft in an area of river channels. During the landing, the aircraft struck trees and ran through a washout. Investigation revealed that the outboard tanks contained between 28 and 30 litres of fuel and that the inboard tanks were dry. No evidence of fuel leakage was found. Fuel-use calculations indicated that the aircraft was actually flown further than would be expected using the aircraft manufacturer's data, and that the pilot who had normally flown the aircraft was not making adequate allowance for fuel burn during flights. The fuel gauges could not be calibrated after the accident.

Significant Factors:

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

1. No record of fuel consumption was maintained for the aircraft.

2. Fuel consumption estimates by one pilot were in error.

3. The other pilot accepted information regarding the fuel state of the aircraft without conducting any check.

4. The pilot did not divert when he became concerned about the fuel state.

5. Fuel tank selections were not changed when the engines stopped.

The pilot reported that, while hover-taxying the helicopter prior to commencing a circuit, it suddenly yawed sharply to the left. He applied right pedal and initially lowered the collective pitch control before raising it. However, the helicopter landed heavily, damaging the front and rear crosstubes. No fault was found with the helicopter which might have contributed to the accident. The pilot reported that he was not sure that an engine failure had occurred but that he reacted instinctively when the helicopter yawed left. Discussion revealed that the pilot rode a motor cycle, the hand throttle of which operated in the reverse sense to that on the helicopter. It is possible that the pilot inadvertently reduced the throttle setting, thus inducing the yaw. His limited flying experience and exposure to engine failure situations then contributed to him lowering the collective pitch control as part of the initial reaction to the yaw. The helicopter was at too low a height to prevent a heavy landing from the descent caused by the lowering of the collective pitch control.