On final approach into Melbourne at 2,000 feet an Engine Information and Crew Alerting System (EICAS) message alerted the crew to an asymmetrical leading edge slat problem. The crew selected flaps to 20 degrees and initiated a go-around. After completing all checklist actions, another approach was commenced with the flaps set at 20 degrees. The aircraft subsequently made an uneventful landing.

The asymmetric slat fault indication is a known 767 problem. Boeing is currently working on a solution to this recurring system anomaly.

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The crew of the Boeing 747 (B747) had made initial radio contact with the Brisbane sector controller and confirmed their clearance to climb to flight level (FL) 350. A few minutes later, the controller decided to resolve a traffic conflict by maintaining the B747 at FL330 and instructed the crew accordingly. The aircraft was passing FL320 when the instruction was passed and, when the crew correctly read back FL330, the controller attended to other work-related tasks.

There were numerous thunderstorms in the area and several track diversions and altitude changes had been made by various aircraft. When the controller next checked the radar display, he noticed the B747 was passing FL340. As there were several aircraft in potential conflict, the controller decided to allow the crew to continue with their climb to FL350 and resolve the separation tasks with radar vectors and altitude changes to other aircraft. He did not inform the crew of any perceived error. The crew believed that they may have omitted to set the altitude selector to FL330. There was no breakdown of separation standards.

The pilot had planned a solo training flight from Canberra to Scone, returning to Canberra via Goulburn the next day. The aircraft departed Canberra with full fuel tanks and continued to Scone without incident, where it remained overnight. The pilot reported that on the return flight the main fuel tanks were used for take-off, and the auxiliary tanks were selected after the aircraft was established on the departure route. Approximately 50 minutes later, when the right auxiliary tank indicated almost empty, the right main tank was selected. However, as the left auxiliary tank still indicated some 10 to 12 gallons, feed to the left engine from that tank was continued.

A short time later, just prior to commencing descent from 9,000 ft into Goulburn, the left engine lost power. The throttles on both engines were retarded for descent and the left main tank was selected to supply fuel to the left engine. The left throttle was advanced some time later but there was no response from the engine. The pilot reported that his troubleshooting checks consisted of checking that the fuel selectors were on the main tanks, the mixtures were full rich, the ignition was on and that the auxiliary fuel pumps were selected to LOW. The left throttle was again advanced but there was still no response from the engine. The checks were then repeated, but with the auxiliary fuel pumps selected to HIGH. Again, there was no response from the engine.

The same checks were performed on both engines but neither engine responded when the throttles were advanced. Both mixture controls were moved to idle cut-off for about 30 seconds. Full rich mixture was then selected, but the engines still failed to respond. As the aircraft was now at a low height, the pilot concentrated on finding a suitable forced-landing site. Just prior to landing on an open field, he had to manoeuvre the aircraft to avoid a wire and a ditch which lay across the intended approach path. The aircraft subsequently landed heavily, sustaining substantial damage. The pilot evacuated the aircraft without injury.

The investigation determined that although the main tanks had been ruptured in the accident, sufficient fuel would have been available for continued operation of the engines. However, an inspection of the aircraft found there was no HIGH auxiliary fuel pump switch position, as reported by the pilot. The three switch positions available were LOW, which runs the auxiliary fuel pump continuously at low pressure, a centre OFF position, and an up position, placarded ON. In the ON position, the pump runs continuously at low pressure until low fuel pressure is sensed by the engine fuel pressure switch. This could occur due to an engine-driven fuel pump failure, or running a fuel tank empty. The pump then automatically runs at high pressure, and is retained in that mode by a latching relay.

If a fuel tank is allowed to run dry, and fuel supply to the engine is restored by selecting an alternate tank, the engine will then be supplied with an excessive amount of fuel, resulting in a loss of engine power due to over-fuelling. To correct that condition, the auxiliary fuel pump switch must be moved to OFF to unlock the latching relay. The flight manual instructions for the fuel system are to select the auxiliary fuel pumps to ON for takeoff and landing, and to use full rich mixture and auxiliary fuel pumps on LOW when changing fuel tanks. Further investigation determined that the right engine fuel pressure switch had a very high electrical resistance after activation.

Consequently, electrical current was able to flow in the latching circuit and lock the system to high flow mode when selected to the ON position. The left engine initially lost power due to fuel exhaustion of the left auxiliary tank. When the main tank was selected, and the auxiliary fuel pump switch was moved to ON, the pump mode changed to HIGH and the latching relay engaged. The consequent over-fuelling condition prevented the left engine from being restarted the right engine stopped from a similar over-fuelling condition when the right auxiliary fuel pump was selected to ON during troubleshooting.

In 1988, the aircraft manufacturer issued Service Bulletin MEB 88-3, which modified the auxiliary fuel pump system and operation because of reported failures of engine fuel pressure switches. The modification included changing the auxiliary fuel pump ON placard to read HIGH. The service bulletin was applicable to all 300/400 series aircraft. However, the modification was not mandatory in Australia and resulted in aircraft in the Australian fleet having differing operational specifications. Service Bulletin MEB 88-3 had not been incorporated on this aircraft.

Modified aircraft have appropriate cockpit placarding and flight manual instructions, but the pilot's operating handbooks do not include the amended instructions. This leads to a misunderstanding of systems operation between different aircraft. The pilot's response to the engine failure was not in accordance with the manufacturer's checklist.

SAFETY ACTION

The Bureau of Air Safety Investigation is currently investigating a perceived safety deficiency identified as a result of this occurrence. The deficiency relates to a misunderstanding of operational procedures on Cessna 300/400 series aircraft as a result of the optional modification state of the auxiliary fuel system (incorporation of Cessna Service Bulletin MEB 88-3).

Any recommendation issued as a result of this investigation will be published in the Bureau's Quarterly Safety Deficiency Report.

The pilot was attempting to land at Numurkah airstrip in gusty crosswind conditions. After a normal approach, the pilot reports having difficulty controlling the aircraft during the landing flare. The aircraft speed decreased, the aircraft stalled and landed heavily on the runway. The nose wheel collapsed, damaging the engine cowl and propeller.

FACTUAL INFORMATION

The helicopter was being refuelled on an oil rig. The fuel sample taken from the oil rig fuel tank before fuelling commenced was clear of contaminant. However, the sample taken after fuelling was completed had a different colour and displayed obvious contamination with fine metallic and other particles. The helicopter was de-fuelled, and its fuel system cleaned before it was released to service. The oil rig operator reported that the contaminant had been inadvertently left in the oil rig fuel tanks after the rig had undergone refit in Singapore. The operator also reported that the fuel was regularly tested, although the testing carried out had not discovered the contaminant.

The contaminant was only discovered when the rig's fuel pumps had been run for sufficient time to refuel the helicopter. The time was probably sufficient to stir the contents of the tank and bring the contaminant into suspension where it was delivered to the helicopter. The refuelling procedures used appeared to have been appropriate to ensure the helicopter did not take off with contaminated fuel. However, the procedures were not adequate to ensure good quality fuel was delivered to the helicopter.

SAFETY ACTION

As a result of this occurrence, the Bureau of Air Safety Investigation (BASI) is reviewing the adequacy of aviation fuel quality control procedures on oil rigs. Any safety action arising from this review will be forwarded to the relevant action agencies and will be published in the BASI Quarterly Safety Deficiency Report.

The Piper Arrow was on a flight from Bankstown to Albury under the visual flight rules. At Goulburn, the pilot elected to return to Bankstown due to low cloud. During the return flight, the pilot noticed the engine oil temperature and fuel contents indications drop to zero. He transmitted a PAN call but received no response. Assuming he had suffered a radio failure, the pilot continued to Bankstown and joined the circuit on downwind for runway 29R.

Bankstown tower controllers, observing the aircraft approaching with the landing gear retracted, unsuccessfully attempted to contact the pilot by radio. They then flashed a red light signal to indicate to the pilot he should continue circling. The common crash call and crash alarm were activated, and a full emergency declared. The aircraft subsequently touched down with the landing gear still retracted, skidding along the runway for about 70 metres before coming to a halt. The pilot vacated the aircraft without injury.

The pilot subsequently reported that when he lost radio contact, he assumed he had suffered a radio failure, although the radio continued to generate static. He continued his return and made a non-radio approach to Bankstown. After joining the circuit on the downwind leg, he selected the landing gear down but did not monitor the landing gear warning lights as he was concentrating on a slower aircraft ahead, and looking for light signals from the control tower. He did not see the red signal light and failed to realise the landing gear was not extended until he landed.

A maintenance check of the aircraft did not find any defects associated with the electrical, radio or landing gear systems which may have contributed to the accident.

FACTUAL INFORMATION

The Boeing 747 (B747) was maintaining flight level 350 (FL350) when the crew received a traffic alert and collision avoidance system (TCAS) resolution advisory, warning of conflicting traffic crossing their track at an altitude 400 ft below. They were able to contact the other aircraft, which was a Douglas DC8 maintaining FL330 in accordance with air traffic control (ATC) instructions.

Both crews were able to maintain their respective levels and no evasive action was required. When the DC8 departed Auckland, ATC verified that the secondary surveillance radar altitude readout had correlated with the reported altitude from the crew. However, on arrival at Honolulu, ATC noted a 1,500 ft difference in the altitude reported by the crew to that showing on the radar display. The aircraft transponder was providing an erroneous altitude, but the crew had no flightdeck display to enable them to check what information the transponder was emitting.

The equipment failure had occurred between departing radar coverage at Auckland and the point at which the B747 crew received the TCAS alert. Initial maintenance action by the company indicated a faulty encoder, but an ongoing investigation in the USA revealed that the central air data computer had been providing faulty inputs to both transponders.

SAFETY ACTION

As a result of this occurrence, the Bureau of Air Safety Investigation is investigating a perceived deficiency involving the lack of information available to flight crews regarding the serviceability of altitude encoders. In addition, the Bureau is investigating the lack of information displayed to crews regarding altitude information being transmitted by transponders. Any recommendations issued as a result of these investigations will be published in the Bureau's Quarterly Safety Deficiency report.

The student with an instructor was practising autorotative landings onto the grass in the helicopter training area in the NE corner of Moorabbin airport. With the student at the controls, the helicopter touched down gently with about 10 kts forward groundspeed. During the ground slide the landing gear skids encountered a patch of sandy loam and dug in. The helicopter lurched nose down. The instructor took over the controls and raised the collective. The helicopter momentarily became airborne before landing firmly. The combined effect of the lurch and the subsequent landing bent the skids, dislodged the aft cross tube supports and caused the main rotor blades to dent the cover to the tail rotor drive shaft.

The instructor had taught students to perform autorotations at Moorabbin for many years. He was surprised at finding a sandy patch in the grassed area commonly used for autorotative touch downs. He has since advised the FAC of the sand hazard. Since the accident, as the grass has progressively dried out in the summer heat, the instructor has noticed several other sandy patches scattered around the airport.

While returning to the airstrip to reload for another spray run, the aircraft experienced severe engine surge with associated rough running. The pilot selected the fuel boost pump on, but with little improvement. He then elected to make a forced landing. While stretching the glide, the aircraft stalled at about five feet AGL and landed heavily in a soft earth paddock. This resulted in the left main landing gear failing, followed by the nose impacting with sufficient force to tear the engine from its mounts. Inspection by the company found the main fuel filter not lock wired allowing the filter assembly to come loose and starve the engine of fuel.