Circumstances:

The aircraft was taking off shortly after the pilot had carried out modifications to the fuel system. This had included removing and replacing fuel lines. A witness reported that prior to commencing the take-off, the engine had been misfiring. This had continued during the take-off run and initial climb until the engine stopped at a height of about 150 feet. The aircraft was seen to turn sharply to the left before entering a steep nose down spin. After about one full turn the aircraft struck the ground near the strip end. The pilot, who was not wearing a helmet, suffered a fatal head injury following the failure of his upper body restraint on impact. The reason for the loss of engine power could not be positively determined.

Significant Factors:

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

1. Undetermined loss of engine power after take-off.

2. Pilot attempted operation with known engine deficiency.

3. Pilot encountered circumstances beyond his capability.

Recommendations:

As a result of the initial investigation, the Australian Ultralight Federation was notified of the failure of the restraint system, together with a recommended solution. The AUF issued an Airworthiness Advisory on the subject in January 1990.

The company was tasked to operate into a strip adjoining a local race course. Details of the strip were obtained from a local pilot, who told a company pilot that there was a powerline at the eastern threshold of the strip. This pilot subsequently gave the strip data to the pilot who flew the aircraft. Upon arrival overhead the strip, the pilot saw powerlines off the western end and thought that these were the lines mentioned in the briefing. He then decided to land into the west. On late final approach, he saw the powerlines over the threshold and flew the aircraft under them. The resultant high rate of descent could not be arrested before ground impact and the aircraft struck the ground in a nose low attitude with the nosegear and propellers. The landing gear and propellers were torn off and the aircraft slid for 112 metres before coming to rest. The cabin was protected from high deceleration forces by the collapsing landing gear and the occupants escaped without injury. It was determined that the strip was not suitable in length or width for the operation of this aircraft type, and the briefing obtained on the strip was not adequate to determine the suitability of the strip.

After a short flight in the local area the pilot made a long low final approach towards the intended landing point. During the approach the pilot temporarily forgot that powerlines crossed the flight path. The aircraft collided with the wires, which were 68 feet agl, and struck the ground in a vertical nose-down attitude about 800 metres from the landing area.

Circumstances:

The owner of the weight-shift controlled aircraft was being given dual instruction in circuit procedures. This involved making normal approaches followed by a low-level go-around. During the fourth go-around, at a height of about 50 feet, the engine suddenly stopped. The instructor took over the controls and attempted a landing in a sparsely wooded area adjacent to the landing strip but was unable to prevent the aircraft from colliding with a tree and striking the ground heavily. A specialist examination failed to reveal any defect with the engine or fuel system. The reason for the engine stoppage could not be positively established. However, the ROTAX 532 engine was fitted with a single ignition system controlled by an unguarded toggle switch mounted on a console in the forward cockpit. The circumstances of the engine stoppage were consistent with the ignition switch being inadvertently bumped off by the front seat pilot.

Significant Factors:

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

1. The engine stopped at a critical stage of the go-around. The reason for the stoppage could not be positively established.

2. Unfavourable terrain for forced landing.

Recommendations:

The Australian Ultralight Federation (AUF) should require ignition switches be fitted with guards to prevent inadvertent movement on all AUF registered aircraft.

The flight was planned to check the onboard survey equipment. After departing Jandakot the aircraft operated to the south of the airfield for about 80 minutes before the pilot advised that he would be extending his operation to the east over the Darling Ranges. The aircraft was then sighted, by several witnesses, over the foothills heading in an easterly direction. These witnesses reported that the engines were not operating normally. A short time later, the aircraft was observed to pass over the dam wall at an altitude of about 25 feet and head down a valley in a northerly direction before disappearing from sight. An inspection of the wreckage indicated that the aircraft had collided with two 30 metre high trees, in a nose high attitude at a low forward airspeed, before falling to the ground below the trees. At impact neither engine was delivering power. The fuel system, which was found to be relatively intact, contained only nine litres of fuel. It was determined that the engines failed due to fuel starvation following the exhaustion of the useable fuel onboard the aircraft. The pilot was then faced with attempting a landing in unsuitable terrain. Evidence indicates that the aircraft departed Jandakot with both the fuel quantity indicating systems unserviceable. Although the maintenance documentation for the aircraft did not indicate that these systems were unserviceable, it is believed that the pilot was aware of the maintenance state of the aircraft before DEPARTURE.

After takeoff, the aircraft was observed to accelerate at a low height above the strip. At the upwind end, the pilot initiated a steep climb and a steep turn to the right, however the aircraft stalled at about 150 feet above the ground. The aircraft struck the ground heavily and slid into a ringlock fence. The pilot freed himself from the wreckage, and the engine which was still running at high speed, was shut down by a spectator. The pilot reported that after the ultralight stalled, he had the stick full back, but the aircraft would not recover. The aircraft stalled as a result of the steep climbing turn but recovery was not effected due to incorrect stall recovery technique.

Analysis of a video recording taken of the take-off run by the occupant of the front seat, indicated that the aircraft became airborne after a ground roll of about 18 seconds. The aircraft then continued in the direction of takeoff for a further 11 seconds at what appeared to be near to takeoff speed. The aircraft did not climb away. It was not clear from the recording whether or not the aircraft was airborne throughout the 11 seconds. At the end of this time however, the aircraft was on the ground and it then veered sharply to the right. At the time the prevailing wind was a left quartering crosswind. The pilot was unable to regain directional control and the aircraft ran off the side of the strip and struck an embankment before coming to rest inverted. No defect was found with the engine or flight controls and the aircraft weight and centre of gravity were within the required limits. The aircraft had been fitted with a braking system and had recorded 27 hours in service since the modification. An examination of the brake shoes revealed an excessive rate of wear to the left brake shoes, and a cable within the braking system was found to be incorrectly adjusted. However, whether these defects contributed to the development of the accident could not be established. The reason for the loss of directional control was not determined.

Before lining up for takeoff, the motor glider pilot estimated that there would be sufficient time for his takeoff to be completed between a landing glider, and the tug aircraft that had just joined the circuit. The takeoff was delayed by the time taken to clear the landing glider from the strip. The tug aircraft, just prior to turning final, was observed to increase power and head towards the departing motor glider which had just commenced its takeoff run. It passed low over the motor glider and the tow rope struck the right aileron of that aircraft. The glider pilot had lined his aircraft up for takeoff on the strip the tug pilot intended to use for landing. The tug pilot stated that his intention was to teach the glider pilot a lesson not to attempt to takeoff in front of him again. In taking this action the tug pilot forgot that the tow rope was still attached and trailing his aircraft.

The pilot reported that when the aircraft was in the cruise at 3500 feet he heard a noise followed by severe vertical and less severe lateral vibration. The aircraft was descended and checks carried out in an attempt to ascertain the cause of the vibration. The cause of the vibration was not determined and the pilot decided to hover taxi the aircraft back to the platform. The aircraft was subsequently landed on a barge without further incident. An inspection of the aircraft found that one of the two lugs on a main rotor blade flapping hinge had failed. The lug fractured as a result of fatigue which originated adjacent to an area of fretting where the blade retaining pin passes through the lug. These lugs had been known to suffer from a defect discovered in service, and the manufacturer introduced a requirement to fit protective washers to the spindle during overhaul in order to prevent the initiating of cracking. The head from this aircraft had been overhauled by the manufacturer some months before the accident and the protective washers were not fitted. The operator had not carried out a recent Maintenance Manual amendment to inspect the lugs of spindles without protective washers. This inspection was not mandatory in Australia at the time of the accident.

The glider was being winch launched. The launch was normal until the glider reached an altitude of about 70 feet above the strip when the winch cable went slack. The aircraft was levelled before commencing a descent and the landing flare was initiated at about 10 feet above the strip. The aircraft then stalled, landed heavily and bounced. The wheel collapsed during the landing roll. The winch engine failed during the launch due to an ignition problem.