Circumstances:

The pilot took off with the intention of doing a local flight. However, he could not locate any lift, so he returned for a circuit. While on very short finals the aircraft encountered undershoot windshear. The right wing struck a small bush some 5 to 10 metres short of the threshold. The wing was further damaged in the subsequent contact with the ground. The particular bush has since been removed.

Significant Factors:

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

1. The aircraft encountered undershoot windshear on very short final approach. This caused the aircraft to undershoot the landing strip.
2. The aircraft collided with an obstruction close to the strip threshold.

Circumstances:

The aircraft was cruising at about 150 - 200 feet above the trees over heavy scrub country when the engine coughed. The pilot started a descent and the engine regained power briefly before stopping completely. Unable to reach a suitable area for an autorotational landing, the pilot avoided two large trees before the aircraft crashed through smaller trees and struck the ground. The aircraft had been operating for some two and one half hours since refuelling to full tanks, which usually provided an endurance of at least three hours. The pilot was in the habit of managing his fuel by reference only to the operating times and by landing to conduct a sight check of the fuel tank contents after about two and one half hours of operations. No reliance was apparently placed on the fuel contents gauge in the aircraft. An inspection of the aircraft after the accident revealed fuel stains over the oil tank, induction plate and main frame. The inspection also revealed that two screws were missing from the carburettor drain tap plate. No signs of the fuel leak were reportedly evident at the previous pre-flight inspection.

Significant Factors:

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

1. Pilot relied on the times of operation for fuel management in flight and did not refer to the fuel contents gauge in the aircraft.
2. Leaking carburettor fuel drain tap.
3. Engine failure through fuel exhaustion.
4. Engine failure over terrain unsuitable for an autorotational landing.

Circumstances:

The pilot under training was practising circuits and landings in preparation for a Commercial Licence test. When the landing gear was extended on the downwind leg, the nose gear light did not illuminate. The instructor changed light bulbs and the light illuminated so the circuit was continued. The landing was normal until the nose gear collapsed during the ground roll. The aircraft was involved in a similar accident in South Australia on 25 May 1989 and had flown approximately 25 hours since being repaired. A technical investigation revealed the down lock hook had fractured across the "U" section and there was excessive wear in all attachment holes and bushes. The down lock hook failed in overload probably as a result of higher-than-normal loads caused by the excessive wear in the drag link/over centre lock system.

Significant Factors:

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

1. Inadequate maintenance and repair following a previous accident.

2. Overload failure of the down lock hook in the nose gear mechanism.

Circumstances:

The pilot had been airborne for approximately 15 minutes, carrying out aerial spraying of a newly planted crop. The paddock being sprayed was bounded on its northern and western boundaries by a fence approximately 1.2 metres high. Directly above, and running parallel with the western fence, was a three strand power line, the lower cables of which were approximately five metres above ground level. The pilot had flown above the power lines on each previous spray run, crossing the paddock from east to west. After completing a procedure turn the aircraft was lined up for the clean-up run from west to east. The pilot stated that he forgot about the power lines until they became visual again at close range. Knowing he would not be able to climb the aircraft above the cables in the distance remaining, the pilot elected to fly between the lines and the fence. The aircraft struck the two lower cables of the power lines, tearing the fin and rudder from the airframe. The aircraft continued airborne for approximately one kilometre before rolling to the right and striking the ground. It then began to break up as it cartwheeled across the paddock, finally coming to rest inverted. An inspection of the area revealed that the poles that supported the power lines would have been difficult to see, when approaching from the west, as their outline merged with trees in the paddock.

Significant Factors:

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

1. The pilot forgot about the presence of the power lines.

2. The pilot did not see the power lines in time to avoid them.

3. The aircraft wire deflector failed on contact with the power lines.

Circumstances:

The pilot reported that the aircraft was part way along a spray run when he heard a change in the engine noise which he described as a hissing/tapping sound. He completed the run but, when the noise increased during the procedure turn, he elected to land the aircraft on a dirt access road between two crops. The aircraft landed with a wind of about 10 knots from the right rear quarter. Shortly after touchdown, the pilot swerved the aircraft to avoid a post. The pilot then experienced directional control difficulties, and the right main wheel entered soft ground at the edge of the central road surface. This caused the aircraft to swing right and enter the crop. As both main wheels encountered the cultivation, the aircraft nosed over, and a fire began in the engine compartment. The cockpit roof was embedded in soft soil. This prevented the pilot opening either door. However, he was able to egress from the cockpit by kicking out the Perspex panel in the left side door. An inspection of the engine revealed that the exhaust pipe from Numbers 1 and 9 cylinders had come loose and was free to rattle and allow exhaust gases to escape past the respective cylinder flanges. This would have caused the noise as described by the pilot. The brass nuts which secure the exhaust to the cylinder head were not found. However, the cylinder head exhaust studs showed witness marks which indicated that neither nut had been in place at impact.

Significant Factors:

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

1. For reasons which were not established, the numbers 1 and 9 cylinder exhaust pipes were not secured to their respective cylinder flanges.

2. Noise from the loose exhaust pipes and escaping exhaust gases attracted the pilot's attention.

3. The pilot elected to land as soon as possible.

4. The pilot lost directional control of the aircraft during the landing roll. Bureau of Air Safety Investigation

Circumstances:

The flight consisted of one aircraft in a group of three positioning a mobile polling booth. After the passengers were unloaded at Oenpelli, the aircraft flew to Jabiru to refuel, and the pilot rested in the air-conditioned snack bar for about five hours. The aircraft was then re-positioned at Oenpelli and the passengers boarded. The aircraft departed from runway 12 as the wind was 120 degrees at 20 knots, gusting to 25 knots. The temperature was about 40 degrees Celsius. This was not the pilot's preferred runway as the Spencer Range escarpment commences within five miles of the DEPARTURE end of this runway, rising rapidly from sea level, through 500 feet to over 1,000 feet. At some point after take-off, the pilot realised the left engine manifold pressure was steadily decreasing. After completing trouble checks, he feathered the left propeller and turned back towards the aerodrome. When turning onto the base leg, the pilot realised the aircraft would not maintain altitude and could not reach the runway. He then elected to land straight ahead on a dry clay pan. The landing gear could not be extended as the left engine drives the hydraulic pump and insufficient time remained for the pilot to manually extend the gear. The aircraft touched down wings level and skidded for about 135 metres. All four occupants evacuated safely once the aircraft stopped. The investigation failed to determine any pre-existing defect in the left engine. However, impact damage to the undersurface of the engine, may have destroyed any evidence of a pre-existing defect.

Significant Factors:

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

1. For undetermined reasons, the left engine suffered a partial or total power failure.

2. The aircraft was unable to maintain height on one engine in the high-density altitude conditions.

The aircraft was operating as Flight QF004/145 from San Francisco to Sydney, cruising at flight level 390 in smooth, clear, moonless conditions. The aircraft Captain occupied the left control position and the Second Officer occupied the right. The weather radar system was serviceable and operating. No significant weather had been forecast or observed by the crew during the flight. Although the "fasten seatbelt" signs had earlier been turned off, passengers had been advised, by cabin announcements, that it was recommended that seat belts should be worn unless moving around the cabin. This information was also included in the passenger safety briefing cards as well as being stamped onto each seatbelt buckle. About six hours after leaving San Francisco, the Captain noticed stars he had observed from his left window were becoming obscured. Upon closer inspection he noticed cloud ahead, and to the left of, the aircraft. Although no weather radar returns were apparent, the Captain took the precaution of turning on the fasten seatbelt signs. Approximately 15 seconds later the aircraft encountered a short period of moderate to severe turbulence. A number of passengers and flight attendants were flung about the cabin, incurring minor injuries as they struck fixed objects. Damage to the aircraft was minor and confined to internal fittings. After considering the condition of the injured, the enroute medical facilities and the superficial nature of the aircraft damage, the Captain decided the flight should continue as planned. The aircraft subsequently landed at Sydney where further medical treatment was provided. Twenty passengers required short term treatment in hospital. The investigation of the incident revealed that the flight crew had operated the aircraft in accordance with approved company procedures. Their knowledge, and use, of the weather radar systems was considered satisfactory. All weather radar systems depend on the fact that water particles, either in suspension (cloud) or as rainfall, will reflect a radar energy beam to an extent generally dependent upon the density and size of the water droplets. The aircraft encountered vertical air currents associated with an isolated towering cumulus cloud, which evidently contained insufficient moisture to be detectable by weather radar.

The pilot was approaching to land at the end of a local soaring flight. He commenced final approach at a satisfactory height and speed. The air brakes were selected half extended in order to control the approach. A short time later the aircraft began to slow down and sink more rapidly than the pilot desired so he lowered the nose and attempted to retract the air brakes. He was unable to retract the brakes and the aircraft struck the boundary fence short of the runway. On later consideration of his actions the pilot found that he had been trying to extend the airbrakes rather than retract them. He considered that this was due his anxiety at the high rate of descent that had developed. The initial high rate of descent was probably a result of unexpected sink encountered on approach.

When the pilot departed the aerodrome the wind strength was reported to be 18 knots. However, by the time the pilot returned for a landing the wind strength had increased significantly with gusts reported to have reached 30 knots. The pilot landed the aircraft successfully, but as he started to taxi a wind gust caused the right wing to rise. The left wingtip then contacted the ground and the aircraft nosed down resulting in the propeller also striking the ground. The aircraft then pirouetted around the wingtip and somersaulted onto its back. The strong wind sprang up during the time the pilot was flying in the local training area. After landing the pilot was unable to attract the attention of persons who could have acted as wing walkers and despite having placed the control column in the full back and full right position, he was unable to prevent the right wing from rising. This accident was not the subject of a formal on-site investigation.

Prior to landing the gear was selected down and a normal gear down indication obtained. The touch down was normal but when the airspeed was reduced to about 65 knots a vibration similar to a wheel shimmy developed. Attempts were made to keep the aircraft straight with brake and rudder but when it was realised that the right maingear was not supporting the aircraft the right engine was shut down. Investigation revealed that the uplock bracket spring had become detached from the uplock bracket. This along with some corrosion and stiffness in the bracket pivot bolt caused the bracket and uplock not to be withdrawn during the extension sequence. As a result the extension rod was bent during the extension cycle and the right gear did not extend. There is no provision made for lubrication of the bracket pivot bolt and no requirement for regular removal and servicing of this item. The pilot was unaware of the gear malfunction due to the design feature of the system which does not indicate gear-leg position but only the extent of gear-box travel.