The aircraft was dispatched from Melbourne with the auxiliary power unit unserviceable. Four minutes after take-off, with the first officer manually flying the aircraft, the crew received messages indicating that a series of services had been lost. These included the left generator control, bus tie, both utility busses and associated systems including all three auto pilots and auto throttle. The aircraft was levelled at 10,000 feet while the crew carried out appropriate check list items.

At the completion of the checks all systems had been regained and the flight continued to Sydney.

Extensive maintenance checks in Sydney failed to disclose the reason for the loss of the left generator. The failure occurred within the systems associated with the left generator bus power control unit. Connectors T105 and C905 were inspected and cleaned, as were the left integrated drive generator connectors. The connectors were a common link within the systems that failed.

Cleanliness of connectors is a continuing problem with many current aircraft. Conditions that affect the performance of connectors include moisture ingress, and the corrosive result of that ingress. Certain cleaning compounds used on the connectors have been found to cause contamination of the connector pins resulting in loss of conductivity. The operator has a continuing program to improve connector performance across the fleet.

The aircraft was dispatched with an unserviceable APU in accordance with minimum equipment list requirements. When the left generator failed the aircraft was being manually flown therefore the loss of automatic flight systems was not critical. The auto load shed system functioned to keep the remaining generator within its rated load parameters. When the crew restored twin generator operation the configuration met the minimum equipment list requirements and a return to Melbourne was not necessary.

Approaching top of climb a strong odour became evident in both the cabin and flight deck. When visible light smoke was noticed the crew initiated a return to Melbourne. During descent the right engine oil pressure fell to zero and the engine was shut down.

Maintenance found engine oil dripping from the engine. The engine was removed for tear down inspection which disclosed that the high-pressure turbine oil pressure tube had ruptured at the coupling nut allowing the engine oil to be pumped overboard. The rupture had originated in an area of deficient fusion in a manufacturing weld. The manufacturer initiated a worldwide x-ray sampling of the tube and published a service bulletin detailing corrective actions to be taken.

The pilot stated that he departed the Aircair base strip at Boggabilla at about 1415 EST after refuelling and proceeded to a farm strip at "Eddlington" nine kms due east of North Star, to spray herbicide.

He approached the strip from the north-west and turned for a straight in approach. The pilot said he had used the strip 2 days before and was familiar with it. The wind was from the west tending south-west at four to five knots, and he landed the aircraft "well to the north end of the strip". He stated that as he touched down the aircraft turned violently to the right through 180 degrees and proceeded backwards and to the right into the sorghum crop where it came to rest. The left wing was damaged, and the rear fuselage was broken. The pilot said that on investigation he found that the right wing had struck a dirt bank concealed by long grass, and this caused the sudden loss of directional control.

It was reported that the right main landing gear leg light failed to give a safe down indication after the gear was selected down during the approach to land at Cummins. The pilot was unable to get a safe indication after using both the normal and emergency extension systems, so he shut the right engine down and moved the propeller to a horizontal position prior to landing. The aircraft settled onto the right flap during the roll-out.

Post-accident inspection indicated that the torque link bolt of the scissors joint of the right landing gear seized and fractured during the take-off from Ceduna. When the landing gear was lowered at Cummins the top arm of the torque link contacted the side of the wheel well, preventing the right gear from being lowered. The grease on the torque link bolt had dried out, probably as a result of the aircraft having been left standing for a long time without use. Lack of lubrication probably led to the bolt failure.

Report not released due to no IP comment from the Indonesian agency on this joint investigation report.

ASOR hard copy held on occurrence file.

Report not to be released without the approval of the Director or a DD.

Signed

Alan L Stray

Deputy Director Investigations

6 July 1998

The crew reported for duty for a scheduled flight from Sydney to Moruya. The co-pilot was to be the handling pilot for the sector. He had recently been endorsed on the Fairchild Metro 23 and was undergoing line training under the supervision of the pilot in command.

After take-off, the aircraft was cleared to climb to 5,000 ft. This instruction was acknowledged by the crew. As the Metro was climbing to the south, opposite direction traffic was a Boeing 737 maintaining 6,000 ft, inbound to Sydney. A short time later the Metro was observed on radar to be approaching 5,600 ft, in close proximity to the B737. The departures controller asked the crew of the Metro to report their altitude, whereupon the aircraft was observed to commence a descent. The Metro passed below the B737 while descending to 5,000 ft.

Recorded radar data later showed that separation between the aircraft was reduced to 1.3 NM laterally, and some 600 ft vertically, at their closest point of approach. The Manual of Air Traffic Services specified that 1,000 ft vertical or 3 NM lateral separation was required at the time.

Both the pilot in command and the co-pilot of the Metro did not recall noticing an altitude alert, which should have provided the crew with both aural and visual warnings 1,000 ft before the aircraft reached the selected altitude. The pitch trim control was being used during the climb, which also provided an aural annunciation through the cockpit loudspeaker. Company procedures required the non-handling pilot to alert the handling pilot some 500 ft prior to the aircraft reaching its cleared altitude. In this instance that procedure was not carried out.

The pilot in command later reported that he had been completing paperwork during the initial climb but felt that the co-pilot appeared to be handling the departure sequence adequately and did not require close supervision. However, the co-pilot said he had working hard to cope with the workload and may have channelised his attention on the speed control of the aircraft.

The breakdown of separation in this occurrence resulted from a combination of factors. These included: the attention of the handling pilot being unduly focussed on the speed control of the aircraft, at the expense of monitoring altitude; and the attention of the pilot in command being diverted from monitoring and supporting the performance of the handling pilot. The aural annunciation of the pitch trim control may have masked the sound of the altitude alerting system.

As a result of this occurrence, the standard operating procedures of the company will be amended to provide additional defences designed to prevent a recurrence.

The pilot reported that during cruise at Flight Level 180, at an outside air temperature (OAT) of -6 degrees Celsius (C) in clear air, with the engine anti-ice selected OFF, the left engine suffered two minor reductions in power (rollbacks). During the first rollback, the engine ignition light illuminated, but did not illuminate during the second occurrence, which occurred approximately 5 minutes later. Some 10 minutes prior to the first rollback, the aircraft had been operating in icing conditions, with the engine anti-ice systems turned ON.

The pilot reported that during the climb-out from Sydney, the indicated OAT was observed to rise from -2 degrees C to approximately +10 degrees C and then slowly reduce to the lower value. There was no apparent change to the ice being carried on the airframe at the time. The crew concluded that the OAT measurement system must have been in error. Subsequent maintenance action found an obstruction in the OAT probe which would cause it to read in error, affecting the proper operation of the engine anti-ice system. It was also considered that the engine rollbacks probably resulted from pieces of ice breaking away from an earlier buildup in the engine air intake.

SAFETY ACTION

Investigation of this incident revealed a problem associated with engine power interruptions on SAAB 340 aircraft. The problem was attributed to ice build-up in the engine intakes subsequently breaking free and being ingested into the engine. This resulted in a momentary power interruption. The investigation also revealed that the manufacturer had initiated a SAAB 340 power interruption improvement program in October 1994 to find a solution to the power interruption problem. The program involves the individual manufacturers of the engine anti-ice systems (General Electric, Cox, and Aerospace Composite Technologies, formerly Lucas), and aims to develop an improved engine anti-ice system.

Proposed design solutions are presently being trialled on SAAB 340 aircraft from several airlines around the world, including the operator of the aircraft in this occurrence. Once a design solution has been finalised, it will be introduced into new production aircraft and offered as a service bulletin to in-service aircraft.

The operator in this occurrence reported that its SAAB 340 aircraft experience "rollbacks" several times per year. Both SAAB and the operator require the engine anti-ice system to be selected on whenever the OAT indicates below +5 degrees C in the presence of visible moisture. In this instance, the proper application of the engine anti-ice system was not possible due to the erroneous readings provided to the crew by the OAT system.

As a result of the investigation into this occurrence, the Bureau of Air Safety Investigation forwarded the following Interim Recommendation IR960144 to the Civil Aviation Safety Authority on 29 November 1996.

"The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority actively monitor the SAAB 340 Power Interruption Improvement Program and ensure that Australian operators are aware of the program and of the outcomes."

The aircraft was returning to Kununurra following a cargo flight to Kalumburu. There was sufficient fuel on board for the flight to Kununurra (71 min) as well as for an additional one hour flying (a company requirement). The fuel was evenly distributed between the right and left tanks. The pilot had planned to use the fuel in the right tank until he passed over Forrest River (approximately 40 min after departing Kalamburu) and then change to the left tank. On departure from Kalumburu the aircraft was climbed to 13,000 ft to check a Kununurra navigation aid before it was descended back to 9,500 ft for the rest of the trip.  When the pilot completed his enroute check over Forrest River he made a note on the flight plan form indicating that he had changed the fuel selector to the left tank.

The pilot elected to complete a straight-in approach to runway 12 at Kununurra. He completed his pre-landing checks, which included a fuel check, 10 km from the airport and prior to commencing the approach. As the aircraft descended through 600 ft, 5 km from the airport, the engine stopped. The pilot changed the fuel selector to the other tank and selected the fuel boost pump to On. When the engine did not respond the pilot turned the aircraft to the left in an attempt to land on a road that the aircraft had just passed over. Realising that the aircraft would not reach the road the pilot selected full flap and landed in a paddock. Although he was able to avoid trees the pilot was unable to avoid a fence and the aircraft ran through the fence and across a road. The collision with the fence caused the nosewheel to collapse.

A post-accident inspection of the aircraft disclosed that the right fuel tank contained 0.5 L of fuel and the left tank 75 L. No faults were found with either the engine or the aircraft's fuel system.

Calculations indicated that a minimum of 155 L of fuel would have been required to complete the trip as planned at 9,500 ft. Inspection indicated that 160 L was used prior to the engine stoppage. The difference of 5 L can be accounted for by the additional fuel used during the climb from 9,500 ft to 13,000 ft.

The pilot could not recall if he actually changed the selector from the right to the left tank over Forrest River nor could he recall which tank he selected after the engine stopped. The selector was found in the Off position during the post-accident inspection, and it is believed the pilot moved it to this position following the accident as an anti-fire precaution.

The evidence indicates that the pilot probably did not move the selector to the left fuel tank over Forrest River and the engine stopped because all the fuel in the right tank had been exhausted.

Information provided by the pilot and his employer indicated that the pilot was suffering from a significant amount of personal stress at the time of the flight. In addition, he had resigned from his job and was due to leave the area the following week. The distraction provided by both the stress and the lifestyle changes may have contributed to the pilot not changing the tank selection although he noted that he had done so.

The fuel situation should have become evident when the pilot completed his pre-landing checks as the aircraft approached Kununurra. However, the pilot reported that although he was aware that one fuel gauge indicated empty and the other indicated over half full the significance of these readings did not register, nor did he check the fuel tank selection. The pilot could not offer any concrete explanation as to why his fuel management did not meet normal expectations. He did indicate that preoccupation with personal events, as mentioned earlier in the report, or an inappropriate mind-set about fuel systems resulting from recent flying experience in the Partenavia PN68 may have been contributing factors.

Safety Action

The operator has taken action to standardise aircraft checklists and procedures, particularly in those areas relating to fuel management. In addition, the operator conducted a seminar for all its pilots to increase their awareness of the part that human factors can play in pilot performance.

The pilot reported that he was practicing circuits and landings at the time of the accident. During an approach for a touch-and-go landing the aircraft encountered windshear at a height of about 15 ft resulting in a heavy landing. The pilot applied power and continued for another circuit.

It was the pilot's normal practice not to retract the gear during circuit training. He noted that the gear indications were still green, despite the heavy landing, during his pre-landing checks for the final circuit.

The aircraft's touchdown appeared normal but both main landing gear legs collapsed during the landing roll.

A post-accident inspection indicated that the right main gear attachment bracket probably suffered an overload failure during the heavy landing, but the leg was held in place by the drag brace thus providing a safe (green) indication. During the final landing the right leg brace failed allowing the leg to collapse. The asymmetric loads then caused the left leg to collapse.

The pilot of the Piper Pawnee had completed spraying the first property for the day. After landing, the operator discussed the next job with the pilot, including the area to treated, the rate of application of the chemical, and fuel management. The operator and his son then drove to the next property to mark a cotton field to be sprayed.

Spraying of the field commenced approximately 30 minutes later. After operating for about 50 minutes the engine stopped as the aircraft was flying at about 10 feet above the crop, during a swath run. The pilot climbed the aircraft to 60 feet, performed a trouble check, and then carried out a forced landing straight ahead into the cotton crop. During the landing the wheels entered soft, muddy conditions. The aircraft decelerated rapidly, pitched onto its nose, and then overturned.

Owing to the wet conditions, it took the operator about 20 minutes to get to the accident site. On arrival he found the pilot walking along a fence line, dazed and in shock, carrying his helmet which had sustained a large crack on the top.

A subsequent examination of the aircraft by the operator found an absence of fuel. The time airborne had exceeded the fuel endurance of the aircraft. In addition, the pilot did not have a reliable means of determining elapsed time to enable him to monitor fuel endurance. It was reported that the aircraft fuel contents indicator was not sufficiently accurate for precise measurement of the fuel tank contents.