On arrival overhead the destination the pilot assessed the wind velocity and decided to land on runway 23, a 610 metre long grass strip. The wind direction was north-north-easterly at 15 knots.

The pilot reported that the aircraft touched down further along the strip than normal, and that braking was poor on the grass surface. About two thirds of the way along the strip he considered going around but did not attempt to do so because of trees at the end of the strip. The aircraft overran the strip and collided with an abandoned vehicle before overturning.

The pilot had inadvertently misread the wind direction, and in doing so had operated the aircraft outside the published landing performance criteria.

The aircraft taxied for runway 27 at Jabiru for a flight to Darwin. There was light rain on the threshold of runway 09 and a wind velocity of approximately 290 degrees at 10 knots with active thunderstorms approaching from the east.

After take-off, the aircraft climbed normally until about 100 feet above ground level, then began to sink. Full power was being indicated on the engine instruments for both engines. However, the pilot noticed that the airspeed was decreasing. He set the best rate of climb speed and selected the landing gear up to reduce drag. The aircraft continued to descend until it struck the runway. It slid along the runway for about 200 metres before stopping. The pilot and passengers vacated the aircraft uninjured.

A witness noticed a wind shift as the aircraft commenced its take-off and it is possible that the aircraft encountered a microburst just after liftoff.

The aircraft, a Sea scan version of the Westwind 1124, was departing for a normal coast watch operational flight. The outside air temperature (OAT) was 30 degrees C, with a north westerly wind at 5 kt. It was loaded to its maximum all up weight (MAUW) and configured for a flapless take-off. This being normal requirements for the aircraft operating at MAUW with an OAT greater than 28 degrees C. The calculated V1 speed was 140 kt, and the VR speed 148 kt.

With the co-pilot at the controls the aircraft taxied the 4 km to the threshold of runway 29 for departure. The take-off run was normal until the aircraft had travelled approximately 2,000 m and accelerated to 128 kt. At this point the left main wheel tyre suffered a blow out causing the aircraft to veer left.

The captain took control and rejected the take-off. Whilst he was attempting to maintain directional control, using brakes and nose wheel steering, the right main wheel tyre also blew out and the aircraft swung to the right, departing the runway and coming to a stop on the flight strip in the reciprocal direction to the take-off.

The left main gear leg collapsed, and the aircraft suffered damage to the left gear attachment structure, left fuel tank cell, and the infra-red dome mounted to the lower fuselage surface. All occupants evacuated safely.

The left main wheel and tyre remains were examined at the CAA Materials Evaluation Facility. The examination revealed that all three fusible plugs in the wheel hub were loose. Although it could not be established if the fusible plugs were tight before the accident, enquires indicated that they had not been touched by any other party prior to the wheel coming into BASI's possession.

The valve, and gasket between the wheel hub halves, were in good condition, and no flaws or defects were found in the tyre material, or its manufacturing process. An uneven wear pattern across the tread was noted, being more advanced on the middle tread and shoulders than on the intervening sections of tread.

The wear along the tyre shoulders is consistent with under-inflation, but as there was also some wear on the middle tread it was apparent that the tyre had been correctly, or possibly over inflated at some time. Over a period of time an undetected slow leak had probably occurred, with the wear pattern indicating that the tyre had been under-inflated for a number of take-offs and landings. In this condition the sidewalls would have been subjected to increased flexing, resulting in excessive heat generation and delamination between the fabric layers. Eventually the tyre would have been unable to sustain these flexing loads, resulting in rapid deflation and shredding of the tyre from the wheel. The aircraft operating at MAUW, the hot tarmac, and long taxiing distance would have exacerbated the situation.

The reason why the fusible plugs were loose could not be determined, but this was considered as the most probable source of the slow leak.

The pilot reported that during the descent into Fitzroy Crossing he diverted to inspect a fishing pool. During the inspection the descent continued unnoticed, and the aircraft collided with an object, later identified as a power line. The aircraft continued to operate normally and landed safely at Fitzroy Crossing.

Whilst conducting pilot training for Search and Rescue helibox dropping, the helibox hit the tail of the leading edge of the horizontal stabiliser. The heliboxes were being dropped out of the front passenger window of the aircraft. The drop was the last for the day and there had been no problems experienced in the previous drops. Turbulence in the area had built up during the day and was causing slight airspeed and altitude fluctuations. CAA manuals recognise that turbulence can cause an increased risk of tailstrike in this type of operation and advise to exercise caution when turbulence is present.

While conducting a pleasure flight the aircraft right rear landing wire failed. The pilot returned to TYABB and landed normally.

The landing wire examination found that the wire failed in fatigue initiating from two subsurface defects in approximately the middle of the wire length.

A sample taken some 40 mm from the fracture surface contained intermetallic stringers reducing the integrity of the material. Size of the stringers was consistent with the size of the subsurface defects. The analysis identified the stringers to be an aluminium based intermetallic, possibly from the refractory material used in production of the material.

The material composition and microstructure was typical of a drawn and rolled 316 stainless steel. The manufacturer advised the wire was made of 316S16 steel.

Circumstances

Panther Cougar Section [4 X Macchi 32] were completing operations in Restricted Area R527. Williamtown air traffic control [ATC] commenced co-ordination procedures with Sydney Sector 2 for clearance to transit civil airspace in order to recover the section to Williamtown.

Due to Sydney ATC internal co-ordination requirements, Sydney Sector 2 were unable to issue a clearance immediately and themselves commenced co-ordination with Sector 1 and arrivals South. At the same time Sector 2 advised Williamtown ATC to contact Sector 1 direct for further instructions.

Williamtown ATC then contacted Sector 1 only to be told to contact Arrivals South. After establishing contact with Arrivals South, Williamtown were then told to contact Sector 2.

As a result of this uncertainty the 4 X MC32 aircraft were diverted clear of civil airspace by Williamtown ATC and the extra flight time resulted in the aircraft landing with eight minutes endurance remaining.

Significant Factors

1. The internal co-ordination requirements for Sydney ATC were cumbersome and unnecessarily complex.

2. The Sydney Sector 1 controller did not obey the principles of point to point co-ordination as specified in the Manual of Air Traffic Services [MATS].

Circumstances

RAAF Williamtown were operating FA18 aircraft in Restricted Areas R457 and R527. In order to return these aircraft to Williamtown at the completion of their task, it was necessary to transit civil controlled airspace under the control of Sydney Sectors 1, 2 and Arrivals.

Williamtown air traffic control [ATC] co-ordinated with Sydney Sector 1 for the recovery of two FA18 aircraft and Sector 1 issued approval and advised of civil aircraft with which Williamtown ATC needed to provide radar separation with their aircraft. Sector 1 also agreed to perform the co-ordination tasks with Sector 2 and Sydney Arrivals, which was correctly carried out.

Williamtown ATC then proceeded to recover their aircraft in accordance with the clearance issued by Sector 1, but as the FA18s were approaching civil airspace, Sector 1 advised of additional traffic VH-TAH whose track and altitude placed the aircraft in potential conflict with Shogun 1/2 [FA18].

Sydney Sector 1 believed that he had only co-ordinated an expectancy of approval with Williamtown ATC but Williamtown believed that they had received a clearance to transit the airspace.

As a result Williamtown ATC radar vectored its aircraft clear of VH-TAH and no breakdown in separation occurred.

Significant Factors

1. The co-ordination procedures for this section of airspace were complex and time consuming which led to confusion as to if an actual clearance was issued.

ASOR 9200127

Circumstances

VH-KLS departed Williamtown for Canberra at 1032 hours on a charter flight using IFR procedures. At 1040 hours the pilot contacted Sydney Flight Service and reported that he was on the 015 radial of the Sydney VOR and maintaining 6,000 ft.

The Flight Service Officer [FSO] held a flight strip on the aircraft but had received no co-ordination from Williamtown ATC. The FSO then contacted Williamtown ATC to ascertain the co-ordination required and was informed that VH-KLS had departed at 1032 hours.

There was no known conflicting traffic and therefore no breakdown in separation.

Significant Factors

1. Williamtown ATC did not co-ordinate the departure time of VH-KLS as required by the Manual of Air Traffic Services [MATS].

VH-STO [PA31] taxied at Port Macquarie for Williamtown at 0241 hours (UTC) and made his departure call on area frequency at 0246 hours.

VH-TQQ [DHC8] was enroute Sydney for Port Macquarie and passed overhead Williamtown at 0242 hours with an estimate for Port Macquarie of 0254 hours.

TQQ was under the control of Williamtown military ATC, and the controller did not pass this position and estimate to Sydney FS in the required time. As a result, the first the Sydney FS officer and the pilot of STO knew of TQQ was when the pilot of TQQ made his passing 10,000ft call on area frequency at 0247.30 hours.

The FSO immediately passed the two aircraft traffic on each other [at 0248 hours] and the Williamtown controller passed the coordination at 0249 hours, with an apology.

The two captains immediately initiated vertical separation until positive passing was established. TQQ maintained 5000ft on descent and STO maintained 4000ft on climb. This separation was established at 0249 hours, and the two crews attained a mutual sighting at 0250 hours. The pilots state that the two aircraft were on track and over the same location at the time of passing.

Weather was cloudy with some breaks and both pilots report being in and out of cloud. TQQ did remain visual throughout the lower part of its descent, but STO was in IMC most of the time.

Significant Factors

1. Williamtown ATC did not coordinate the Williamtown position report for TQQ to Sydney FS in the required manner.

2. Only appropriate and timely action by the Flight Service Officer and both crews avoided a separation incident.