The pilot had been soaring in wave conditions, when sink was encountered and an outlanding became necessary. The field initially selected was obstructed by a power line and the pilot manoeuvred towards another area. On late final approach the aircraft collided with a single strand power line and subsequently struck the ground heavily. The pilot later advised that he had seen a pole supporting the line but had thought it was aligned in another direction. The large distance between the poles supporting the power line reduced the possibility of the pilot being able to accurately assess the direction of the line.

Circumstances:

The pilot had almost completed spraying herbicide on a field of cotton which was bordered in part by the Dawson River and its associated tree line. The pilot reported that he was making a right turn over the river, which is a conglomerate of channels and gullies, to position the aircraft for a cleanup run. During the turn, he was trying to assess whether a single run would suffice, or if two runs would be required to cover the curved northern boundary of the paddock. The pilot stated that he then suddenly became aware of foliage directly in front of him. The aircraft struck the branches of a large gum tree, lost a 2.5 metre section of right wing, dived into the ground, and came to rest inverted 75 metres from initial impact. There was no fire despite both wing tanks being ruptured. The battery was thrown from the aircraft at initial ground impact. The wing tanks were foam filled, which reduced fuel spillage when the tanks were ruptured, and prevented fuel spraying over the wreckage whilst the aircraft was breaking up. The pilot was wearing protective clothing including a helmet, overalls, and boots. The safety harness was in good condition and did not fail. The cockpit remained intact despite complete destruction of the fuselage, and consequently the pilot was protected from sustaining other than minor injuries and was able to extricate himself from the wreckage.

After a cross country soaring flight, the pilot made an outlanding in a paddock short of his destination. The pilot reported that the paddock was about one kilometre wide and one and one half kilometres long, covered in short dry grass with some scattered thistles. While waiting for the tug aircraft to arrive, the pilot inspected the paddock and decided that a takeoff into the west would be the best course of action. The wind at the time was approximately five knots from the south-west. The pilot reported that the takeoff was normal with the glider lifting off at about 40-45 knots. While flying at about two feet above the ground, waiting for the tug aircraft to lift off, the right wingtip of the glider hit a large thistle or group of thistles. The glider swung to the right, the left wingtip lifted and the right wingtip contacted the ground. The glider was then 90 degrees to the tug and at about 20 degrees of bank. The tow rope was released and the glider swung almost 180 degrees from the takeoff direction. The glider remained airborne for about another 40 metres before the left wing and tail section hit the ground, bringing the aircraft to rest shortly thereafter. The pilot advised that although he thought he was extremely unlucky for this accident to have occurred, he now thinks that the paddock was not a suitable takeoff area.

The pilot reported that the engine stopped on the downwind leg whilst the aircraft was at an altitude of 200 feet. He originally considered landing across the strip but changed his mind and attempted to land along it. Touchdown was heavy and the right main landing gear (laminated wood) broke. The aircraft skidded to a halt on the right landing gear stub.

It was reported by the owner of the aircraft, that after about two hours and 15 minutes flying the pilot checked the contents of the fuel tanks. He estimated that four hours fuel remained. However, after a further two hours flying the engine failed following the exhaustion of the fuel onboard. The pilot was committed to a landing on unsuitable terrain, and during the landing roll the aircraft struck a tree and ground looped.

The pilot was returning from a solo navigation exercise and had descended from 800 feet in the training area to 300 feet above ground level to comply with the height restrictions on ultralight aircraft. The engine began to run roughly and the aircraft lost height to about 200 feet. The pilot elected to carry out an immediate precautionary landing on the Stuart Highway as he was flying downwind and was uncertain of his ability to turn into wind for a landing if he lost any more height. A normal landing was made in the centre of the highway, but the aircraft diverged to the right and the pilot was unable to maintain directional control on the camber of the road. The aircraft then hit the roadside windrow and collided with bushes. No mechanical defects were found that could have contributed to the loss of engine power. Conditions were conducive to the formation of carburettor icing which would have been assisted by the use of Mogas fuel. Club officials stated that the limit on the altitude of ultralight operations prevented the pilot from flying at a greater height, and therefore denied him the opportunity of selecting another area for landing which was clear of obstructions.

Circumstances:

The pilot had been unable to obtain details of the strip before his departure for the area. On arrival he conducted an inspection of the strip from 500 feet. He noticed that there was no windsock and that a power line had been installed across the northern end since his previous visit. He also noted that the strip changed colour along its length and that vehicles had been driving along it. After this inspection he conducted a landing from the south. On touchdown he saw a bank where the traffic path entered the strip. As it was then too late to initiate a go-around the pilot tried to avoid the bank. This was not successful and the nose gear leg was broken off on colliding with the bank which was about 1.5 metres high. It was determined that the landing area had been de-commissioned about a year earlier.

Significant Factors:

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

1. The pilot did not obtain information from the strip owner or permission to land at the strip.
2. The pilot did not conduct an adequate inspection of the intended landing area.
3. The aircraft was landed on an unsuitable area.

Circumstances:

The aircraft engines performed normally during the run up, taxi and take-off. At approximately 500 feet after take-off, the pilot noticed the right hand engine manifold pressure gauge indication slowly decreasing. Thinking that the throttle friction may have slipped, he advanced the right hand throttle. There was a momentary pause in the decreasing manifold pressure reading. The right hand throttle was gradually advanced to the full power position, however, manifold pressure continued to decay. Following completion of the trouble checks the pilot shut down the right hand engine and feathered the propeller. Because the flight was only a six minute positioning flight, for maintenance purposes and the aircraft was performing to his satisfaction on one engine, the pilot elected to continue to Parafield. He advised air traffic services of the engine failure and of his intention to proceed to Parafield. The aircraft subsequently made an uneventful single engine landing. At the end of the landing roll the pilot who was wearing a headset, heard the fire warning bell. At the same time, he noticed for the first time that the right hand engine bay fire warning light was illuminated. A post-flight inspection revealed substantial fire damage within the right hand engine bay forward of the firewall and a large section of the number four cylinder head was found lying in the lower cowling. The cylinder head had failed at the threaded joint of the head and barrel. Metallurgical examination showed that the fatigue failure had developed over a period of approximately 900 start/stop cycles. However, the development of the crack would probably have been visible to external inspection only during the latter 15 start/stop cycles prior to failure. The failure was probably the result of defective cylinder maintenance and assembly techniques and heat treatment used during overhaul. The engine fire had developed in the vicinity of the failed cylinder and spread throughout the engine bay fed by raw fuel through the cracked cylinder head and burnt fuel lines. It is likely that the fire self-extinguished when the pilot turned the electric fuel pump off and shut the engine down. The engine bay fire warning system apparently activated and because it had not been detected by the pilot, remained activated until after the landing. The warning system did not self-cancel after the fire abated. The aural warning system was found to be inaudible at high power settings and due to the ambient light conditions prevailing during the take-off into bright sun and glare, the steady red fire warning light was not noticed by the pilot. Approved check lists did not include a check of the fire warning system as part of the emergency procedures cockpit drill.

Significant Factors:

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

1. Defective techniques used during cylinder assembly maintenance and inspection.

2. Cockpit visual fire warning system for the engine bay operated but was not evident to the pilot under the ambient light conditions.

3. Aural fire warning could not be heard at high power setting.

4. Aural fire warning bell was not connected to audio system.

5. Aircraft emergency procedures check list did not specify pilot monitoring of fire system following engine failure.

Recommendations:

1. That the Civil Aviation Authority give consideration to: Improving surveillance of maintenance organisations where cylinder heads and barrels are separated by heat treatment with particular emphasis on:

a) techniques used in the control of heat processes during strip down and reassembly procedures such that temperatures attained do not cause softening of the alloy, and

b) reminding maintenance personnel of the necessity to maintain due care during the disassembly and reassembly stages of cylinder overhauls where heating is required, and

c) achievement of sound inspection techniques and practices.

2. Ensuring that general aviation aircraft equipped with on-board fire detection and extinguisher systems are able to provide the pilot with such vital information concerning an in-flight engine fire by:

a) changing any steady fire warning light/s to a flashing red indication;

b) ensuring that such red fire warning light/s are ergonomically placed in the pilot field of vision to permit immediate recognition of activation;

c) ensuring that where an aural fire warning system is incorporated, the minimum volume be adjusted such that it be audible under all power settings with and without noise suppressing headsets;

d) conducting a study of the feasibility of incorporating an aural fire warning alarm for reproduction through the cockpit audio system; and

e) amending emergency procedure check lists to incorporate a check of the fire alarm system where fitted.

The pilot had been conducting a six and a half hour low level survey flight. He stated that on joining the circuit, at the completion of the flight, he lowered the landing gear and obtained a gear down indication. The gear indication was again checked on final approach but during the subsequent landing roll, as the nosewheel was being lowered to the runway, the landing gear handle in the cockpit sprung to the up position. The landing gear retracted and the aircraft slide to a halt on its undersurface. An inspection of the aircraft could find no pre-impact defect with the landing gear or its systems which could have contributed to this inadvertent retraction. The landing gear was found to be capable of normal operation. The reason for the selector deselection remains undetermined.

The pilot was conducting a short cross country flight. As he approached the end of the final leg he realised that there was insufficient height available for the aircraft to make a safe landing at the destination aerodrome. A decision was made to attempt an out-landing as the aircraft passed through 1200 feet on the descent. At that height the choice of fields was restricted and the one that was chosen for the landing was unsuitable. The landing area was covered with long grass and sloped downwards and from right to left. A shallow gully also crossed the area. During the final stages of the approach the right wing touched the ground and long grass causing the aircraft to yaw violently and enter a ground loop. The aircraft finally touched down whilst it was travelling sideways and it came to rest after travelling backwards along the paddock. The pilot was not authorised to conduct cross country flights in the particular aircraft type as he had not completed the required number of flight hours and landings. This accident was not the subject of an on scene investigation.