Interim report released 11 July 2008

On 7 February 2008, a Boeing Company 717-200 aircraft, registered VH-NXE, was being operated on a scheduled passenger service from Cairns, Qld, via Nhulunbuy (Gove) to Darwin, NT, with six crew and 88 passengers. During an ILS approach to runway 29 at Darwin Airport, the aircraft touched down on the runway at a high rate of descent which resulted in a hard landing. The crew completed the landing rollout and taxied the aircraft to the terminal without further incident. The extent of aircraft damage constituted an accident

On 7 February 2008 at Tamworth Aerodrome, New South Wales, an air traffic controller issued a take-off clearance to the flight crew of a Bombardier Inc DHC-8-315 (DHC8) aircraft, registered VH-TQZ, for runway 30 Right. At the same time, an airport operations officer was operating a vehicle on that runway.

The controller had previously issued a clearance to the operations officer to conduct bird dispersal activities on the runway. The operations officer was monitoring his radio and heard the DHC8's take-off clearance. He advised the controller that he would vacate the runway. At the same time, the flight crew had observed the vehicle on the runway and did not commence the takeoff. The controller cancelled the take-off clearance until the runway was clear.

While these secondary safety defences effectively prevented any possibility of an accident, the issue of the take-off clearance with the vehicle on the runway constituted a breakdown of separation.

The investigation found that the controller's scan of the runway and flight strip board was not effective as a result of his pre-occupation with the management of current and pending traffic and the associated high volume of radio communications. It was also possible that the controller was experiencing some degree of fatigue at the time. The ATSB's investigation did not detect any safety issues that required consequent safety action.

On 14 January 2008 the pilot of a single-engine Cessna Aircraft Company 208 conducted a successful forced landing back onto the departure runway after the aircraft's engine failed. The flight, with six passengers onboard, had earlier departed Townsville, Qld on a private Instrument Flight Rules (IFR) flight to Mt. Isa.

The evidence showed that the failure of the engine was precipitated by the fracture and separation of a single blade from the compressor turbine (CT) disc. The gross mechanical interference caused by the release of that blade into the confines of the turbine section contributed to the subsequent forced fracture of the other CT blades and the downstream migration of blade debris. The remainder of the internal engine damage was identified as secondary damage as a result of that debris.

Damage to the area of crack initiation limited the extent of examination such that the root cause of fatigue initiation could not be established with certainty. However, from the available evidence, it was considered likely that the crack initiated at a localised area of stress concentration, such as may have arisen from the passage of foreign object debris through the engine, from handling or tooling damage sustained during a prior maintenance activity, or from the effects of an isolated blade casting anomaly that was not evident to the examination.

At approximately 1224 Eastern Standard Time on 11 January 2008, a Boeing 737-200 aircraft, registered VH-OBN, was intercepting the localiser for an instrument landing system approach to runway 01, Brisbane Airport, Qld. The operating crew for the passenger flight included two flight crew (pilot in command (PIC) and copilot) and three cabin crew. The copilot was the handling pilot.

The copilot had reported to the PIC that he was feeling a bit uncomfortable. Shortly after, the copilot handed over control of the aircraft to the PIC and vacated the cockpit due to pain and discomfort.

The PIC continued the approach and landing, without the copilot. Following the landing, as the aircraft entered the taxiway, the copilot returned to the cockpit and resumed support duties until the aircraft reached the gate.

Following the event, the copilot was diagnosed with and received treatment for diverticulitis.

Preliminary report released 19 February 2008

On 7 January 2008, a Boeing Company 747 438 aircraft, registered VH-OJM, was being operated on a scheduled international regular public transport service between London, England and Bangkok, Thailand. The aircraft had 346 passengers and 19 crew on board, including four flight crew.

At about 0837 UTC, while the aircraft was at about 21,000 feet on descent to Bangkok International Suvarnabhumi Airport, the customer service manager (CSM) notified the flight crew that a substantial water leak had occurred in the forward galley.

Between approximately 0840 and 0852, cockpit indications showed a number of electrical bus and system failures that indicated alternating current (AC) buses 2, 1 and 3 were not powered. The status of AC bus 4 appeared normal and some systems were powered by batteries.

The captain's primary flight display, navigation display, and some other instruments were available in a degraded mode. Standby instruments and the aircraft's instrument landing system were also available. The crew conducted an approach to runway 01 Right in day visual meteorological conditions and the aircraft landed at 0907.

On 11 January 2008, the aircraft manufacturer issued a Multi Operator Message to operators of 747 400 series aircraft, containing advice and instructions for the inspection and repair of main equipment centre drip shields. The manufacturer is preparing an inspection and repair alert service bulletin on the same subject that is scheduled for release by May 2008.

On 11 January 2008, the aircraft operator issued a Cabin Standing Order and a Flight Standing Order requiring cabin and flight crews to treat and report abnormal water accumulation in galley areas.

On 29 November 2006, an Australian Army Black Hawk helicopter, A25-221, crashed during a training flight. The helicopter was attempting to land on HMAS Kanimbla located in international waters off Fiji. Onboard the helicopter were 10 army personnel - four aircrew and six soldiers. Of those onboard, eight survived and two were fatally injured.

The helicopter sank in deep water and the flight data recorder (FDR) was recovered in March 2007 after a salvage operation. The Australian Department of Defence was responsible for investigating this accident and appointed a Board of Inquiry. The Department of Defence requested ATSB assistance in the recovery of data from the FDR. The Executive Director of the ATSB approved the request. To protect the information supplied by the ATSB to Defence and investigation work undertaken to assist Defence, the ATSB initiated an investigation under the Transport Safety Investigation Act 2003.

The solid-state memory was successfully downloaded and a copy of the data file was provided to a representative from the Directorate of Defence Aviation and Air Force Safety.

Information publicly released by the Board of Inquiry is available on the Department of Defence website: http://www.defence.gov.au

Preliminary report released 8 February 2007

On 24 December 2006, the owner-pilot of an Auster Aircraft Company J1/A1 aircraft, registered VH-ALO, was intending to ferry the aircraft from a private airstrip at Nelson, Vic, to Akuna station S.A. The pilot was the sole occupant. At approximately 0930 Eastern Daylight-saving Time, the pilot commenced a take-off towards the west. Three people were standing between two hangars that were to the north of the airstrip, and they observed that the aircraft became airborne before it reached the taxiway leading from the hangars to the runway. When the aircraft was adjacent to the taxiway, it made a low-level right turn towards the hangars.

One witness, who was an experienced pilot, reported that the aircraft climbed suddenly just prior to striking a power line that was located on the airstrip side of the hangars. The aircraft then drifted over open space between the two hangers on a northerly heading; the left wing was seen to drop and the aircraft impacted the ground almost vertically. The pilot was fatally injured.

On 29 December 2006 at 1330 Western Daylight-saving Time, an Embraer EMB-110P2 Bandeirante aircraft, registered VH-FNP, departed Kununurra Airport, WA, enroute to Argyle. The aircraft was being operated on a charter flight with two pilots and one passenger onboard. The pilots later reported that, during climb out following take-off, while passing through 500 ft above ground level, the right engine lost power. The pilots confirmed the power loss, completed emergency procedures, that included shutting down the right engine, and returned to Kununurra Airport. There were no injuries to the flight crew or passenger and no damage to the aircraft.

Subsequent examination of the engine compressor turbine (CT) blades from the engine indicated that they had been subjected to a 'high temperature creep' event, leading to stress rupture of the CT blade assembly.

The investigation could not determine when the engine had sustained the localised high temperature heating of the compressor turbine components.

On 20 December 2006, a Kawasaki KH4 helicopter lost collective pitch control and impacted terrain while performing agricultural aerial spray operations approximately 21 km NE of Mount Gambier, SA. The helicopter was substantially damaged, but the pilot was uninjured. When the accident site was surveyed, the main rotor mast and main rotor blade assembly were found to have separated from the helicopter. They were located a short distance away.

Examination of the wreckage revealed that the helicopter's main rotor mast thrust bearing had failed catastrophically in flight. That bearing was a critical item for safe operation and continued airworthiness of the KH4. It supported the full weight of the helicopter and transferred thrust loads generated by the main rotor blades during flight.

The investigation was unable to conclusively establish the factors that led to failure of the mast bearing. No evidence was found of manufacturing or material defects. Nor was there any evidence of improper installation procedures or maintenance practice. Based on the inspection of aviation databases in Australia and North America, the main rotor mast thrust bearing failure appears to be an isolated event for the KH4-series helicopter.

Despite the low probability associated with a mast bearing failure of this type, the consequences of such an event could have been fatal for the pilot onboard. This report has been provided to Australian operators and maintainers of Kawasaki KH4 and Bell 47G3 series helicopters as a future alert for this type of occurrence.

A Saab 340B passenger aircraft, registered VH-UYA, experienced a left engine malfunction during the take-off roll at Mount Isa airport. In response to the abnormal engine condition, the flight crew rejected the take-off and shut down the left engine. When the engine was subsequently disassembled by the engine manufacturer, it was revealed that a single stage-four power turbine blade had fractured at the blade root. The liberated airfoil section caused secondary damage to the power turbine and exhaust sections. Metallurgical analysis of the fractured blade revealed that a pre-existing crack had been present at the blade root for a significant period of engine operation prior to the incident malfunction.