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.

Circumstances:

The aircraft was making an intermediate landing for refuelling before proceeding to Lord Howe Island. The pilot reported that soon after carrying out his pre-landing checks on crosswind leg for runway 28, the right engine failed completely. He identified the engine and feathered the propeller. On downwind leg he carried out a trouble check and attempted three times to unfeather the propeller but was unable to do so. He broadcast that he was turning base for an asymmetric landing, reselected gear down, and lowered full flap in stages on final approach. After flaring, the aircraft floated a considerable distance. Approximately halfway along the 696-metre grass strip, while still airborne, the pilot elected to go around. He applied full power to the left engine, selected gear up and retracted flap in stages as the aircraft started to climb. The aircraft then began an uncommanded roll to the right, associated with a loss of directional control, and the right wingtip struck an aircraft parked about 100 metres to the north of the runway 28 centreline. It then cartwheeled across an adjacent car park before coming to rest a few metres short of a refuelling depot. The pilot had elected to use runway 28, although runway 03/21 was available with a landing distance available of 1586 metres. At the time of the accident the wind was reported as light and variable. The right engine was test run, using the original propeller which had sustained only minor damage. No fault could be found through the entire power range and restarting from the feather position was accomplished without problem.

Significant Factors:

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

1. Loss of power on the right engine, for undetermined reasons.

2. The asymmetric approach was poorly planned.

3. The pilot delayed his decision to initiate a single-engine go-around.

4. The pilot did not obtain/maintain flying speed, resulting in loss of control.

This aircraft was intended to be the production version of the "Stratos" aircraft. The prototype version had successfully flown some 340 hours. The production model incorporated significant changes made by the designer/pilot. These changes included the removal of the dihedral from the main wing and the use of full span elevators on the canard wing and full span ailerons on the main wing. The engine mounting was lowered such that the ducted propeller was totally below the main wing and the lower part of the propeller duct was extended well forward to form a "channel or strake". The main purpose of the "channel wing" was an attempt by the designer to lower the stall speed of the aircraft to 30 knots and to reduce both landing and takeoff speeds and distances. As far as the investigation could determine, the effect of these modifications had not been checked by wind tunnel or other methods prior to this flight. On the day of the accident the pilot and his assistants had worked at the factory preparing the aircraft for testing. The preparation included a determination of the centre of gravity, although no record was kept of these calculations. Following these preparations the aircraft was loaded onto a trailer and taken to Penfield. The weather conditions at the time were fine, with light winds. The pilot subsequently carried out a series of taxying tests, to establish the optimum position for the control column. He then conducted a take-off, and operated in the local area for about 17 minutes. Witnesses reported that the aircraft then carried out a very slow pass over the aerodrome at a height of between 400 and 500 feet above ground level. About one minute later it was seen to turn back towards the strip. However, shortly after the turn was completed, control of the aircraft was evidently lost. It is uncertain whether the aircraft suddenly pitched nose up or nose down, but all witnesses agreed that it then fell vertically while the nose swung in a pendulous motion. The aircraft struck the ground in an inverted attitude with little or no horizontal speed. An inspection of the aircraft found that all airframe components were essentially intact and there was no indication of any airframe or control failure prior to ground impact. The engine was test run and strip inspected and no fault could be found. No aerodynamic testing was carried out on the airframe to determine the likely effect on performance of the various modifications made to this aircraft. However, given that the prototype appeared to suffer no adverse flying characteristics, it is possible that the modifications incorporated in the new aircraft had an adverse effect on the stall characteristics. Analysis of the modifications indicates that the most significant effect on the stall characteristics would have resulted from use of full span elevators on the canard wing. The use of full span elevators results in a relatively uniform loading of the canard as the elevator is deflected approaching the stall. The result is that the canard would be developing more lift, compared to the same wing without full span elevators, before the wing stalled and the stall would be sharper. Because the main wing is still producing lift at this stage the nose down pitch following the stall of the canard would be aggravated. It is considered likely that the accident sequence was initiated by a full canard stall followed by a rapid nose down pitch. Also, the altitude at which the flight was conducted would not have allowed the pilot time to make the necessary corrective control imputs following the stall before the aircraft impacted the ground.

The pilot reported that the helicopter was cruising at 2000 feet when, without warning, there was a complete loss of engine power. During the subsequent forced landing, the tail boom struck the ground, causing the tail rotor gear box to separate from the aircraft. Investigation revealed that the engine accessory gear train had failed, causing both magnetos to cease operation. The gear train failed due to lack of torque followed by the fatigue failure of six screws that attach the accessory drive gear to the starter gear. The cause of the loss of torque was not established.

Prior to the flight the pilot had contacted the owners to obtain details of the strip. This briefing apparently did not include the information that the surface of the strip was undulating and had soft sandy areas. After arriving over the destination the pilot flew along the strip a number of times to check the surface. The wind was calm and he elected to land down the slope. The aircraft bounced and floated along the strip before touching down again. During the landing roll, the nosegear leg failed. The pilot was holding the control column in the neutral position during the landing roll. An aircraft engineer who inspected the aircraft found no evidence of any pre-existing fault in the nosegear leg. This accident was not the subject of a formal on scene investigation.