VH-DXO was conducting crosswind circuits on runway 06 (circuit direction right hand). VH-MYS, inbound from the southwest, was given traffic on VH-DXO and instructed to join downwind for runway 14 (circuit direction also right hand). VH-MYS was also instructed to report "approaching the circuit".

As VH-DXO was about to turn onto right base for runway 06, VH-MYS passed in front of VH-DXO at right angles tracking on a right downwind leg for runway 14. The pilot in command of VH-DXO estimated that the two aircraft missed by about 10 metres. The pilot of VH-MYS reported on downwind immediately after the near collision but had not reported approaching the circuit as requested by air traffic control.

Significant Factors

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

1. The pilot of VH-MYS did not report approaching the circuit as requested by air traffic control.

2. Lookout by the pilots of both aircraft was ineffective.

3. The instruction issued to VH-MYS by air traffic control to report approaching the circuit was too vague as this is not a specific position and is open to individual interpretation.

Safety Action

It was considered that this incident may have been averted if VH-MYS had been instructed to report at a specific location approaching the circuit rather than instructed to report approaching the circuit area which was vague and open to interpretation. This aspect was discussed with air traffic control supervisory personnel at Melbourne who will be taking standardisation action on the matter.

A report from the pilot indicated that he made a steeper than normal approach to a private strip. The aircraft landed some distance in from the threshold before bouncing back into the air. The pilot elected to apply power and go around for a further circuit. Despite application of full power, the aircraft did not clear obstacles beyond the end of the runway, and the pilot was forced to land in an adjacent paddock. The aircraft landed heavily.

The Boeing 767 crew requested departure from Perth via a scenic flight along the Swan River. Air Traffic Control (ATC) advised the crew to expect approval for this modified departure track. Due to traffic and noise abatement requirements, the aircraft was initially cleared to maintain runway heading after take-off. The crew acknowledged the clearance.

The aircraft was seen to commence a right turn, at 1600 ft, after take-off, conflicting with traffic departing off another runway. Shortly after ATC queried the crew's actions, the aircraft was seen to return to runway heading. By the time runway heading was regained, the aircraft had reached 2500 feet and was subsequently cleared to track via the Swan River.

Although separation reduced to below the minimum required, there was no danger of collision due to the horizontal displacement, between the aircraft, and the high rate of climb of the Boeing 767.

Runways 31 (left and right) were in use at Moorabbin. VH-IBL landed on runway 31L and vacated the runway via runway 22. VH-NBE was then given a clearance to take-off. Just after the aircraft became airborne, the student pilot abandoned the take-off. VH-IBL had inadvertently re-entered runway 31L and the student pilot of VH-NBE believed that his aircraft would not clear the other aircraft. The instructor assumed control of the aircraft and manoeuvred it around VH-IBL.

The pilot of VH-IBL had only recently been issued his private pilot licence. Although he was an experienced glider pilot, he was not very experienced at Moorabbin. He said that after vacating the runway he had had to taxi around a stationary aircraft and believed he had become disoriented and re-entered runway 31L.

The instructor in VH-NBE had watched both VH-IBL and the aircraft ahead of it land and taxi. He stated that VH-IBL had not taxied around the preceeding aircraft. He said the preceeding aircraft was well ahead of VH-IBL and was not a factor in the occurrence. He also believed that it was unnecessary for his student to abandon the take-off as their aircraft would have been well clear of VH-IBL.

After a normal preflight check had been carried out, the aircraft departed Bankstown. Soon after levelling off at 1500 ft the crew noticed an air noise from the left emergency exit which appeared to be partially dislodged. The pilot informed air traffic control of his intention to return to the airport but almost immediately the exit hatch separated from the aircraft. The aircraft landed without further incident.

The design of the emergency exit release mechanism permitted the handle to be moved to the locked position while the forward latch remained unlocked. The preflight inspection involved viewing the position of the handle through a cutout in the handle cover to ensure that it was locked. While the pilot had completed this inspection, it provided no guarantee that the exit was properly locked because the pilot cannot see if the locking pins have located correctly.

The investigation established that maintenance on the exit was not required, nor was it performed during the aircraft's last periodic inspection on 16 December 1993. The aircraft was not subsequently flown until the incident flight. However, on 29 December 1993 the operator reported that this aircraft may have been tampered with, together with two other aircraft belonging to him.

Significant factors

1. The emergency exit handle may have been moved by an unauthorised person or persons.

2. There was no means of alerting the pilot that the locking pins were not correctly located in the emergency exit locking mechanism.

Safety Action

As a result of this investigation the Bureau issued the following Safety Advisory Notice:

Safety Advisory Notice SAN 940101

The Bureau of Air Safety Investigation suggests that the Civil Aviation Authority consider the applicability of the provision of a suitable method(s) by which a pilot can obtain positive information on the locking status of the forward latching mechanism of the emergency exit in PA-44 aircraft.

The Bureau also suggests that the Civil Aviation Authority ascertain whether a similar problem exists with other aircraft types.

Prior to landing, the landing gear was selected down and the pilot reported that he had normal down and locked indications including illumination of the single green light, the visual arrow indicating down and the nosewheel visually checked down via an external mirror. On the landing roll the left wing lowered until the propeller and wingtip hit the runway. After the aircraft came to a stop, the pilot got out to find the left main gear had not extended.

Investigation revealed that on this particular aircraft model, the single green light that indicates the landing gear is down and locked, is activated by a switch which closes when the actuator has moved to its full extent of travel. Further investigation revealed that the actuator arm linking the actuator to the left main gear was bent. This prevented the arm from extending the left main gear. The reason the actuator arm was bent was not determined.

The aircraft was cruising at 4,500 feet when the engine stopped without warning. The pilot landed in a partially cleared paddock, the only suitable area. During the landing roll the aircraft struck trees, and the nose gear was torn out. The aircraft nosed over, coming to rest inverted.

Failure of the magneto drive gear caused the engine failure. Investigation found the detached gear in the engine oil sump. The aircraft had suffered a recent propeller strike (130 hours prior) and it appeared that the gear had been defective for some time. The fracture face was discoloured from carbon/oil deposits. It is possible that the two events were related.

The pilot reported that, shortly after take-off and after selecting the landing gear up, the landing gear lights, and the panel lighting dimmed and then extinguished. On checking the alternator output he found that there was no electrical power and began emergency procedures. Unable to restore electrical power, the pilot attempted to lower the landing gear using the emergency system. However, the emergency system jammed before the landing gear could be fully lowered. He subsequently landed the aircraft with the landing gear retracted.

Examination of the aircraft found that the landing gear had been fully retracted on landing. Both the normal and emergency gear systems functioned correctly when tested. The electrical system failure was caused by inadequate output from the alternators, and battery discharge. The right alternator drive belt tension bracket had broken, and the drive belt had fallen off. The left alternator was able to produce only 5 A due to a shorted diode. Battery discharge soon after take-off suggests that these faults may have occurred during the previous flight.

An electrical charging fault had been reported on 30 December 1993. The maintenance organisation responsible for the aircraft had cleared the fault on 31 December 1993 with an entry indicating that both alternator drive belts had been tensioned and the operation of the alternators had been checked.

Unrestrained freight in the cabin of the aircraft was packed to the level of the cabin windows and was abutting the rear of the front seats. This would have limited the pilot's access to the emergency gear operating handle.

The pilot reported that the aircraft suffered a gradual reduction in power after take-off. The aircraft was force landed onto a railway line and suffered major damage. Subsequent investigation disclosed no apparent fault with the engine. The VW conversion fitted to this aircraft is prone to carburettor icing. The aircraft was operating on mogas which has a very low tolerance to carburettor ice.

Significant Factors

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

1. The engine suffered a gradual power reduction.

2. The pilot was forced to land on unsuitable terrain

The flight was planned as a fire spotting flight. All systems were normal during the pre-flight, start and after start checks. The aircraft took off towards the east. The wind was reported as blowing from a southerly direction at approximately 10 knots. Witnesses reported that, after liftoff, the aircraft climbed at a very steep angle and very slow airspeed to approximately 300 feet above ground level. At that point the aircraft entered a flat spin to the left and completed four turns prior to impact 110 metres to the left of the runway centreline and 300 metres from the start of the take-off role. The engine ran at a high-power setting throughout the flight.

A post-accident inspection of the wreckage did not disclose any aircraft failure that might have contributed to the accident. The inspection did determine that the aircraft was not fitted with an aural stall warning device, similar to those fitted to all the other PA18 aircraft used by the Operator.

A row of trees, designed to act as a wind break, is located along the southern side of the flight strip. These trees may cause some turbulence when a southerly wind is blowing.

The pilot advised that he was concerned about possible turbulence from the trees and the crosswind effect on the aircraft. As a result, he attempted to climb the aircraft above the trees as soon as possible after liftoff. During the climb the pilot was distracted by the aircraft's proximity to the trees, and he did not monitor the airspeed closely. He allowed the airspeed to reduce and at approximately 300 feet above ground level the aircraft stalled and entered a flat spin to the left.

The pilot had no warning of the stall. There was no pre-stall buffet, and the aircraft was not fitted with an aural stall warning device.

The pilot attempted to recover from the stall, but the aircraft impacted the ground before his attempt had any effect.

It is possible that had an aural stall warning been fitted to the aircraft it would have alerted the pilot in sufficient time to prevent the loss of control.