Loss of control

Circumstances:

The aircraft had been flown twice that day prior to the accident flight. No problems or unserviceabilities had been reported. The purpose of this flight was to take a youth for a joy flight and the passenger emplaned while the engine was still running after the previous flight. After take-off, the aircraft was seen by several witnesses to fly low over the strip and adjoining areas before starting a manoeuvre at low level which resulted in the aircraft apparently stalling. The aircraft was then seen to rotate several times before crashing in a near vertical attitude through several branches of a large tree. Witnesses ran to the aircraft and found the pilot dead, but they were able to free the surviving passenger from the rear seat. It would appear that at the time of the accident, the pilot was carrying out some form of impromptu display at low level or "showing off". The investigation established that the pilot was want, at times, to show off or enjoy "pushing it" or taking an aircraft to its limits. Although it was not possible to determine the exact manoeuvre performed by the pilot which lead to his loss of control, there is no doubt that he carried out a manoeuvre at low level that resulted in the aircraft stalling at a height insufficient for recovery. Such a manoeuvre was apparently induced by the pilot rather than as a result of his experiencing a problem with the aircraft. No faults or anomalies were detected in the aircraft that could have contributed to the accident. All witness evidence is consistent in that the "spin" or spiral occurred after the aircraft entered the turn at low level. During his earlier flight in the aircraft that day, the pilot was reported to have performed aerobatic manoeuvres. The aircraft was not certified for aerobatic flight, and no record was found of the pilot holding an endorsement to perform aerobatic manoeuvres.

Significant Factors:

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

1. The pilot was engaged in an unauthorised impromptu display at low level.

2. The pilot stalled the aircraft at a height insufficient for recovery.

3. The pilot attempted manoeuvres beyond his level of experience.

Recommendations:

It is recommended that the Civil Aviation Authority

1. Require evidence of logbook endorsements for aerobatic manoeuvres, Biennial Flight Reviews, and other logbook only entry qualifications to be recorded on the departmental pilot history file.

The pilot had been airborne for about forty minutes when he decided to outland to talk to the ground mustering party. He selected a strip of ground, as an Authorised Landing Area, with sparse low mulga scrub on the sides and a patch at the end of the proposed landing area. Although the pilot overflew the selected area to check for obstructions, he did not carry out his customary low level inspection of the landing surface. The subsequent landing roll was reported to be smooth and uneventful. After talking with the ground party, they departed and the pilot elected to take off in the opposite direction to his landing as there was nil wind. About halfway down the strip on the takeoff roll, the pilot felt the left wheel strike an obstruction and the aircraft slewed to the left. It then ran through some mulga, about 35 metres to the left of the centre of the strip, as it paralleled the takeoff direction. The pilot recalled seeing an airspeed of about 40 knots at this point and as the aircraft was now clear of the scrub, he decided to continue the takeoff. The aircraft was recovered without further incident. The accident was not the subject of an on-scene investigation and the above information was provided by the pilot. Although the pilot's decision to continue with the takeoff did not contribute to the cause of the accident, it is considered that this was an error of judgement on his behalf. Subsequent examination of the damage revealed, amongst other things, that the right elevator balance horn had been torn off. Such damage could easily have led to control surface flutter, component failure and loss of control.

Circumstances:

The pilot was mustering cattle to clear rising flood waters. A second pilot was on the flight to assist and to observe the first pilot's methods of operation. The aircraft was landed near a gate to allow the second pilot to disembark, open the gate and provide further assistance from the ground. The aircraft then took off and the pilot mustered cattle for about the next 15 minutes. The approach prior to the accident was made from the North at about 15 feet with a wind of about 360 degrees at 15 knots. After passing over the cattle, the aircraft pulled up to about 100 feet and levelled for about three seconds. The cattle were now behind and to the right of the aircraft. The left wing and the nose dropped, and the aircraft entered a steep, descending turn to the left until it hit the ground. No pre-accident defects were found with the aircraft. A search of the aircraft logbooks revealed no discrepancies which could have contributed to the accident. Discussions with the observer pilot and pilots who had conducted initial mustering endorsement and subsequent training, indicated a lack of awareness in their own training of airspeed judgement when flying near the ground. Little importance seems to be attached to the different ground speeds when flying into or down wind and the associated perception of airspeed, while the airspeed indicator seems to be largely ignored with wind sound changes used to judge airspeed.

Significant Factors:

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

1. The pilot failed to maintain airspeed.

2. The aircraft entered an inadvertent stall with insufficient height to recover.

3. Pilot training. It is likely that the pilot's training had not placed sufficient stress on the effects of low level manoeuvering in windy conditions whilst relying on airspeed judgement from ground features.

Recommendations:

1. It is recommended that the Civil Aviation Authority surveillance of instructors conducting cattle mustering endorsements, ensure that both ground and air instruction covers the effects of manoeuvering at low level in windy conditions, particularly the awareness of airspeed. Reference CAO Section 29.10 Appendix 1 paragraphs 2(b) (ii) and 2(b) (iii).

The pilot was making an approach in light wind conditions to a 600 metre long strip. Undulations on the surface were such that the slope in the landing direction varied from about 7 up to 4 down. The pilot was using a short-field landing technique. Touchdown occurred just prior to the threshold, and the aircraft bounced. Full power was applied, but the aircraft then touched down heavily 100 metres in from the threshold. The noseleg broke at the fork, the propeller struck the ground several times and the aircraft came to rest at the edge of the strip. The strip did not meet the published requirements for an ALA suitable for Private category operations. The premature touchdown short of the threshold may have resulted from visual illusions associated with the strip slope. The aircraft had stalled during the attempted recovery from the bounce after initial touchdown.

The pilot reported that he had difficulty obtaining effective braking during the landing roll, due to a grassed, wet strip surface. He was able to initiate a groundloop near the end of the landing roll but the aircraft drifted sideways off the side of the strip prior to the upwind threshold. Very heavy rain had fallen during the previous night and up until 30 minutes prior to the landing, and there were areas of standing water on the strip. The airstrip was not suitable for the intended operation.

When the pilot arrived at the destination, he noted that the wind direction indicator showed apparently calm conditions. Almost immediately after touchdown the aircraft began to swing to the right. Attempts to correct the swing were unsuccessful and the left gear leg collapsed. After vacating the aircraft the pilot noticed that there had been a quartering tailwind of about 10 knots during the landing. The pilot was inexperienced on the operation of tailwheel type aircraft, this being his first flight on such a type following a two hour endorsement. This accident was not the subject of an on-site investigation.

During the daily inspection prior to a series of glider towing operations, the pilot noticed that the brake linings were worn. During the landing roll following the third of these operations, the right brake failed and the aircraft ground looped before coming to rest. The brake had failed following the loss of hydraulic fluid from the seal for the brake caliper piston. This was caused by excessive piston travel, associated with severely worn brake linings. When the assembly was dismantled, it was found that the linings had worn completely off the backing plate, and those on the pressure plate were only 1.1 millimetres in depth. Both brake discs were pitted from the effects of corrosion, which would have caused the excessive wear in the linings.

After a normal touchdown a swing to the right developed. The swing was controlled initially with rudder, but when the brakes were applied the pilot was unable to maintain directional control. After the aircraft had swung through about 120 degrees the left wheel was dislodged. The left main axle assembly had separated from the leg because a bolt had failed and a section of the broken bolt had jammed between the brake unit and the brake disc, locking the left wheel. The locked wheel caused the remaining bolts to fail. The bolt that failed was found to have been worn by fretting. The aircraft had only operated 20 hours since servicing was carried out to the gear legs. The failed bolt had not been changed at that service.

CICUMSTANCES The pilot and his passengers were touring in the north-west of Australia. For a number of landings after the DEPARTURE from Parafield the aircraft displayed a tendency to veer to the left side of the runway. The aircraft was checked by a licenced aircraft maintenance engineer and no defects were found. However, the pilot continued to experience the same problem. For the landing at Erong Springs, the aircraft was landed with a slight crosswind from the left. Shortly after the nosewheel was gently lowered onto the runway, the aircraft once again veered to the left. The pilot did not regain control of the aircraft, which ran off the runway and collided with a tree. A thorough inspection was made of the aircraft following the accident but no fault could be found that may have affected the landing performance. The reason for the aircraft diverging to the left during the landing roll could not be determined.

During the aero-tow launch the right wing of the glider contacted the ground and the glider began to veer to the right. After travelling about 40 metres in this manner the glider was seen to climb steeply, to about 15 feet above the strip, then roll to the left before impacting the ground nose first. An inspection of the glider did not reveal any faults that were likely to have contributed to the accident. It is probable that the pilot was slow to react to the loss of directional control following the wing drop, and delayed in releasing the tow rope. The pilot of the tug aircraft stated that shortly after his aircraft became airborne he felt it being pulled to the left of the strip. He immediately released the tow rope. There was long grass along the side of the strip and it is likely that once the wingtip entered this, the task of attempting to regain directional control was made more difficult for the glider pilot.