As the aircraft became airborne at Adelaide Airport, air traffic controllers observed a tread separating from a main landing gear tyre.

The pilot was advised and confirmed an abnormal landing gear indication. Most of the tread of a main gear tyre was found on the runway and emergency services were placed on full alert.

The aircraft was operated clear of the circuit to reduce landing weight and to allow emergency services to be made ready. Later, after an inspection fly-past was carried out, the aircraft landed safely.

There have been other tread losses from the same type of re-treaded tyre. As a result, the operator has reduced the number of times this type of tyre will be re-treaded and has also stopped the purchase of this type of tyre.

The pilot reported that Melbourne Control had instructed him to call Melbourne on 126.0 Mhz at Yass, which he did. He was not aware at the time that this frequency was in fact a Melbourne Flight Information Service (FIS) frequency. The aircraft was at Flight Level 180, in controlled airspace. As a result, communications between ATC and the aircraft were disrupted, during which time the aircraft commenced descent without a clearance. The pilot should have called Melbourne Control on 126.6 MHz.

It was determined that the correct frequency was passed to the flight crew.

On selecting gear down at 130 kts, two loud bangs were heard from the vicinity of the right hand wing root. The nose gear down indicator light was illuminated but no lights were present for the main gear and the landing gear motor was still running. Emergency extension procedures were carried out with no change to the indications. On landing, the left main gear collapsed.

Engineering examination has not been able to determine the cause of the landing gear failure.

The aircraft was being radar vectored, heading 105 degrees, for an approach to land on runway 34 at Melbourne Airport. The Air Traffic Controller issued an instruction for the pilot to turn onto heading 080. In response the crew read back 010, but the controller did not detect this error.

Observing the aircraft on a near north track the controller asked the pilot to confirm heading 080. In response the crew said "affirmative," instead of reading back the assigned heading. Suspecting a compass failure the controller told the crew to turn right, intending to stop the turn when the aircraft was on an easterly heading. This turn was not made.

Following further communications, the aircraft was radar vectored and positioned for a visual approach on runway 34. A normal landing followed.

Significant Factors

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

1. The crew misunderstood the heading given to them by the approach controller.
2. The controller did not detect the error in the crew read back of the new heading.
3. When asked to confirm heading 080 the crew incorrectly replied "affirmative," instead of stating the actual heading.

The aircraft had been cleared for a visual approach to runway 23 at Adelaide via the Quarry turning point, with a request to maintain best possible speed on descent due to following traffic. Subsequently, the aircraft was observed to overfly Quarry towards the aerodrome at RAAF Edinburgh and was vectored, by air traffic control, to join the final approach path.

The crew of the aircraft advised that they were aware of their mistake and suggested that a higher-than-normal descent speed had caused them to overshoot the turning point.

There was no confliction with any other aircraft.

The incident occurred just prior to official first light, during a shift change in both the control tower and the departure/arrivals centre and during a busy period.

During multiple departurers in suitable weather conditions, the aerodrome controller is required to retain the aircraft on tower frequency and provide positive visual separation (diverging tracks) until the aircraft are handed off to the departure controller.

VH-FWJ and VH-MLX were departing, in turn, from runway 21 on the Perth to Ballidu track. Departure instructions were given to the aircraft which would allow them an unrestricted climb on headings 30 degrees apart (VH-FWJ on 360 degrees and VH-MLX on 030 degrees). When the departure controller passed the instructions to the aerodrome controller for relay to the aircraft, the aerodrome controller was reminded that he would be responsible for visual separation. However, the controller forgot to instruct the aircraft to remain on the tower frequency.

Both aircraft transferred to departure frequency shortly after take-off. VH-FWJ commenced its turn on to 360 degrees as it passed through 1000 feet, 4 nautical miles from take-off. VH-MLX (with a better climb performance than VH-FWJ) commenced its turn on to 030 degrees as it passed through 1000 feet 2 nautical miles from take-off. The resultant tracks placed the aircraft in potential conflict.

Although the potential conflict was recognised by both the aerodrome controller and the departure controller, corrective instructions had to be passed to the aircraft by the departure controller, resulting in a short delay between when the potential conflict was identified and the aircraft were able to respond. As a result the radar returns came within half a nautical mile horizontally and less than 200 feet vertically. Although the two radar returns appeared to be very close together, the aircraft were observed to be visually apart at all times.

The investigation disclosed that although the traffic load was normal for that time of the day it was significant enough to prevent a comprehensive shift change briefing from being carried out in the tower. Evidence also indicated that the aerodrome controller was distracted by the activity associated with the shift change and this plus the combination of low external light conditions and high workload led to temporary task saturation. Consequently the aerodrome controller did not complete his assigned tasks nor did he register the reminder given by the departure controller.

SIGNIFICANT FACTORS

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

1. The aerodrome controller was distracted from his assigned tasks by the shift change which occurred during a time of high workload and less than optimum light conditions.

2. The aircraft had significantly different climb performance, with the climb profile of VH-FWJ being about half that of VH-MLX.

3. The provision of positive separation instructions from the tower was made difficult because the aircraft were not on the tower frequency. The delay associated with the provision of this information by the departure controller, although not excessive, was sufficient for the conflict to occur.

SAFETY ACTION

The following safety enhancement action was taken after the occurrence.

1. The Civil Aviation Authority reminded relevant Perth staff of the requirements for the application of visual separation during departure.

2. The Civil Aviation Authority took action to rearrange the tower shift change over so that it occurs prior to the known busy period which starts around 0600.

The aircraft was flying over the Grampians Mountain ranges, the highest peak of which is nearly 4000 feet. The pilot reported that he had diverted slightly to the north of track to avoid the higher peaks of the first range but also to keep clear of a storm to the south and to keep below cloud. As the flight proceeded, the pilot realised that the aircraft was not going to clear the rising ground. He attempted to turn away from the rising ground but realised that the aircraft was going to sink into the trees in the heavily timbered terrain. The pilot lowered flap and stalled the aircraft into the tops of the trees, estimated to be between 20 and 30 metres high.

The aircraft was destroyed as it fell through the trees to the ground. The two occupants spent the night at the site. Early the next morning, when there was no longer any sign or smell of fuel, they turned the radio on and made a call to Melbourne, after which search and rescue procedures were commenced.

The pilot initially believed that the engine had suffered some form of power loss. The wreckage was inspected by an aircraft engineer who reported that damage to the propeller was consistent with the engine delivering significant power at the time of propeller impact. The Bureau of Meteorology advised that there were active thunderstorms in the area at the time with the possibility of severe downdrafts. In addition, conditions were conducive to the formation of carburettor ice. However, an eyewitness reported that the wind was calm, and the sky was clear at the time of the accident.

The accident was not formally investigated by the Bureau, and it was therefore not possible to determine significant factors that could be supported by sound evidence.

Shortly after lift-off, at about 50 feet, the right engine surged and lost power. The pilot was unable to control the yawing effect and attempted a landing beyond the departure end of the airstrip. During this attempt the engine surged to power once but as this exacerbated his control difficulties the pilot closed both throttles. The aircraft cartwheeled after striking the ground with the left wingtip. The aircraft came to rest in a paddock beyond the 1,000 metre airstrip.

The fuel selector for the right engine was found in the auxiliary position. The pilot later commented that he probably missed the fuel selection out of his pre-take-off checklist. He said that he had been in the habit of using a memorised checklist for the operation of the aircraft and at times he had forgotten to switch the tank selection from auxiliary to main tank prior to landing, as required by the operating instructions in the aircraft flight manual. The pilot also commented that he felt uncurrent in asymmetric operations.

Examination of the right engine did not reveal any defects which could cause a power loss.

Significant Factors

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

1. The pilot did not follow flight manual operating instructions for the operation of the aircraft fuel system.

2. The pilot relied on a memorised checklist.

3. The pilot was uncurrent in asymmetric operations.

On selecting gear down, there was no green light indication in the cockpit and the landing gear motor continued to operate. The pilot noticed that both main gears were trailing. He was unable to retract or extend the landing gear by either the normal or emergency extension systems. The aircraft was landed in this configuration.

Investigation found that the retaining circlip in the hydraulic ram for the left main landing gear door had failed. This allowed the actuating ram to separate from its housing and seal, causing the loss of all hydraulic oil from the landing gear reservoir.

The cause for the circlip failure could not be determined.

Shortly after commencing the take-off the aircraft made an uncommanded turn to the right and ran off the sealed runway. Before the aircraft could be brought to a stop the left propeller was damaged as it struck a T-VASIS box.

The crew had deactivated the nosewheel steering system during the early portion of the take-off, in accordance with standard operating procedures. An extensive investigation by the operator and manufacturer did not disclose the cause of the uncommanded turn.

The manufacturer recommended, and the operator has adopted, a modified procedure aimed at avoiding a repetition of this incident.