The aircraft was cleared via a Standard Instrument DEPARTURE with an unrestricted climb to Flight Level (FL) 220. The aircraft climbed on track at an average rate of 1300 ft/min until FL130. The rate of climb then reduced to 350 ft/min until FL140, when the rate of climb increased to 1800 ft/min. At FL160 the aircraft entered a near vertical descent and radar contact was lost one minute later at 3100 feet. The aircraft impacted the ground in a near vertical attitude. Despite an extensive investigation, the reason for the loss of control leading to this accident could not be determined. There have been several other reported occurrences involving sudden loss of control in this aircraft type and the United States Federal Aviation Administration has conducted a certification review of the type. The results of that review do not appear to indicate any factors relevant to this particular accident.

During a flight earlier in the day, the pilot noted that an airspeed indicator he had fitted was not operating. This had been of no concern, as the original indicator fitted to the aircraft was functioning correctly. After landing and rectifying the defect in the new indicator, the pilot elected to carry out a further short flight. At about 200 feet after take-off the engine failed, and while attempting to restore power the pilot forgot to monitor the airspeed. The aircraft stalled at a height of about 100 feet, and the pilot was only able to regain partial control before the aircraft struck the ground heavily. The reason for the loss of engine power has not been established. This accident was not the subject of an on scene investigation.

As the final sequence of a licence test flight the examiner requested the pilot to carry out a normal autorotative landing from circuit height. The aircraft was flared slightly high, recovered but subsequently contacted the ground in a tail low attitude. It then bounced forward and the tail boom was severed by the main rotor. The aircraft flight manual specifies that touchdown following an autorotative descent must be made with the landing skids level. On this occasion touchdown was made on the heels of the skids, and the resulting oscillations of the aircraft allowed the main rotor blades to sail and strike the tail boom.

On initial touchdown the pilot detected an abnormality with the landing gear. An immediate go around was carried out and the pilot of another aircraft reported that the left main gear was sloping rearwards of its normal alignment. The pilot was committed to a landing with the gear in this position and the gear leg subsequently collapsed at about 60 knots. Initial investigation indicated that the failure of a slotted pin allowed the trunnion forward pivot pin to work itself free, with consequent misalignment of the gear leg. The pivot pin showed evidence of grinding, apparently carried out during maintenance in order to facilitate the fitting of the pin into its appropriate socket. However, the grinding also resulted in excessive free play, which allowed the pivot pin to apply bending loads to the slotted retaining pin and which resulted in the eventual failure of this pin.

As the aircraft was nearing the end of the landing roll, the Tower Controller observed smoke briefly issuing from one of the wheel assemblies. The crew was alerted, and reported that a hot brake temperature warning was indicated on the flight deck. The smoke had not persisted, and the pilot in command elected to continue taxying to the terminal area, in order to allow a normal disembarkation of the passengers. He requested the Tower to monitor the situation. The Airport fire services were summoned and followed the aircraft. Another Tower Controller then reported that fire had broken out in the left maingear. The aircraft was halted and the pilot in command ordered an evacuation. The evacuation proceeded smoothly, but injuries resulted from the use of the escape slides. The fire crews rapidly extinguished the fire and assisted with the evacuation process. Investigation revealed that an electrical short circuit had occurred in a solenoid in the anti-skid system which controls the brakes on one of the left mainwheels. This led to the brakes on the affected wheel being applied continuously. The resulting overheating in turn led to the eventual disintegration of the brake disc and pads, and the outer covering of an hydraulic line caught fire. Considerable overheating of the tyre and wheel rim also took place. The crew had no direct communication with the fire crews on site, and were unaware of the extent of the fire. This had left the pilot in command with no alternative but to order the evacuation of the aircraft.

The aircraft had been refurbished during the preceding months, and at the completion of this work the pilot intended to carry out a short test flight. He subsequently reported that as soon as the aircraft became airborne after a normal take-off roll, it veered sharply and the right wing dropped. Corrective control inputs had no effect, the wing and propeller struck the ground and the aircraft overturned, coming to rest about 200 metres from the start of the take-off roll. The surface wind was reported to be varying up to 30 degrees off the runway direction, and gusting up to 15 knots. Because of the degree of damage sustained however, it was not possible to determine whether the wind conditions or the rigging of the aircraft was the major factor contributing to the accident.

Shortly before the aircraft landed a tractor had finished slashing the strip. The driver had not noticed any soft areas, and the strip appeared to be of a uniform colour. As the aircraft decelerated to about 20 knots during the landing roll, the nosewheel suddenly broke through the strip surface and sank to a depth of some 30 cm. Shortly afterwards the wheel snapped off near the bottom of the strut, which then folded rearwards and the aircraft skidded to a halt on its nose. The strip was in regular use, however this had been the first landing since isolated heavy rain had fallen over the area two days previously. It was probable that the rain had affected a small section of the strip, but not to the extent where the soft patch was detectable by aerial or ground inspection.

Arrangements had been made for three Tiger Moth aircraft to carry out a fly-past at Walcha as part of celebrations to commemorate the first Australian superphosphate spreading operation by air. Earlier in the day VH-BII was flown from Williamtown to Maitland and Scone, where all three aircraft were refuelled in readiness for the flight. The pilots briefly discussed the flight procedures to be used enroute to Walcha and agreed that the pilot of the aircraft planned to take-off last would be responsible for navigation for the group. There was little or no discussion about how the aircraft would form up after take-off prior to departing on track. The aircraft were positioned for take-off with VH-BII planned to be the second of the group to become airborne. The first aircraft took off normally and commenced a left turn when at a height of about 500 feet. VH-BII was observed to follow a similar pattern, however the third aircraft commenced a right turn after take-off to intercept the track to Walcha. Shortly afterwards VH-BII, which had made a gradual turn to the left through about 45 degrees was observed to rapidly enter a steeply banked turn to the right. The angle of bank increased and the aircraft entered a spin. Any recovery action attempted by the pilot was unsuccessful and the aircraft struck the ground in a steep nose-down attitude after passing through a set of power lines. Fire broke out immediately and engulfed the wreckage. Subsequent investigation did not disclose any defect or malfunction of the airframe, engine or systems of the aircraft which might have affected the pilot's ability to safely control the aircraft.

This flight was to be the pilot's first flight in a minimum aircraft. He was briefed to carry out a take-off and landing along the beach. When the aircraft became airborne a left bank was adopted and right rudder was used to attempt to regain directional control. As speed was increased directional control was achieved but oncoming obstructions made further manoeuvring necessary. After starting to climb, directional control was lost. The aircraft crashed into trees and caught fire. The pilot mentioned to his rescuers that the ailerons had been inoperative. The pilot later succumbed to his injuries in hospital. Investigation of the apparent aileron failure was hampered by the degree of fire damage to the aircraft. This damage was a result of the inability of the plastic fuel tank to withstand the impact with the ground. The precise cause of the accident remains undetermined.

Circumstances:

Whilst cruising at 2000 feet the propeller separated from the engine, damaging the upper starboard wing leading edge. During the ensuing forced landing further damage was sustained to the landing gear and elevator. Investigation revealed the crankshaft had suffered a fatigue failure, causing the propeller to separate from the engine. The pilot reported the crankshaft had been in service for 150 hours and that all recommended modifications had been incorporated.