A fire on board a bulk carrier that took five days to contain and extinguish highlights the lack of adequate regulatory requirements and standards to address the known risk of fire on-board self-unloading ships, an ATSB investigation has found.

The 202 metre, Australian flagged self-unloading bulk carrier Iron Chieftain was discharging its cargo of dolomite at Port Kembla, New South Wales in the early hours of 18 June 2018 when friction, probably from a failed bearing, generated enough heat to ignite a rubber conveyor belt in the C-Loop internal cargo handling space. (Self-unloading bulk carriers are equipped with a series of conveyor belt systems and spaces that enable cargo to be unloaded without requiring shore-based equipment.)

During a regular safety round of the self-unloading system during cargo discharge operations, a crew member detected a strange smell and white smoke that abruptly changed to black as the crew member approached the deck casing door for the C-loop space.

The ship’s crew then initiated an emergency response but shipboard efforts to control the fire proved ineffective, with the fire soon establishing itself and spreading to the exterior of the ship, setting the discharge boom alight. The ship’s crew were eventually evacuated and Fire and Rescue New South Wales (FRNSW) firefighters took charge of the response to the fire. The fire was contained and eventually extinguished about five days later.

The fire caused substantial structural damage including breaches of two fuel oil tanks, and much of the self-unloading system was destroyed. The ship was subsequently deemed uneconomic to repair and declared a constructive total loss before it was towed to Turkey for recycling. However, there were no serious injuries or marine pollution reported as a result of the fire.

“The fire on board Iron Chieftain demonstrates how the effectiveness of a shipboard response to a fire depends primarily on the ability to detect the fire at an early stage and quickly extinguish it at the source,” said ATSB Chief Commissioner Greg Hood.

“Iron Chieftain’s self-unloading system was not equipped with a fire detection or fixed fire-extinguishing system in the C-Loop space, but nor was it required to be.

“This highlights the lack of adequate international standards or regulations for dedicated fire detection and fixed fire extinguishing systems in cargo handling spaces of self-unloading bulk carriers.” 

The ATSB’s investigation report also notes that the initial emergency response by the crew, in particular stopping the conveyor belts, aided the fire’s early development as heat could not dissipate.

“Following ignition, the combination of high fuel loads in the form of rubber conveyor belts in the C-Loop space and airflow from the vertical design of the loop and its ventilation fans, meant the fire quickly established itself and travelled along the C-Loop’s rubber conveyor belt system to the ship’s exterior to the deck discharge boom and set it alight,” said Mr Hood.

In addition, heat from the fire in the C-Loop space caused thermal stress, cracking and deformation to the adjacent heavy fuel oil tanks, releasing additional fuel for the fire and increasing its intensity and complexity.

“The ATSB recommends the introduction and improvement of international standards for suitable fire detection and fixed fire-extinguishing systems in the cargo handling spaces of self-unloading bulk carriers and the introduction of standards for the fire resistant properties of their conveyor belts,” said Mr Hood.

“The absence of these measures has been a contributing factor in at least three major shipboard fires over a 25‑year period, including Iron Chieftain.”

Mr Hood said the ATSB welcomes the commitment by the Australian Maritime Safety Authority (AMSA) and Lloyd’s Register to approach the International Maritime Organization (IMO) and the International Association of Classification Societies (IACS) respectively, to highlight the safety issue regarding the inadequacy of fire safety standards or regulations for self-unloading system spaces.

“Nonetheless, the ATSB is recommending that AMSA formally raise the safety issue with the IMO to initiate safety action aimed at addressing the risk of fire in the cargo handling spaces of self-unloading bulk carriers due to the inadequacy of the current associated standards and regulations,” he said.

Separately, the investigation notes that while the operators of Iron Chieftain had identified the fire risk in the ship’s cargo handling space due to the lack of fire detection and fixed extinguishing systems, particularly in the C-Loop space, about five years earlier, the prevention and recovery measures it put in place were not sufficient to mitigate the risk.

In response to the Iron Chieftain fire, the operator’s parent company, the CSL Group, initiated a fire risk mitigation project across its global fleet of self-unloading bulk carriers to improve fire detection and suppression technology, reviewing its firefighting policy and setting minimum fire safety standards for early fire detection and suppression at the ship design and build stage.

Finally, the ATSB also identified a safety issue relating to Fire and Rescue New South Wales’s marine firefighting capability as well as other safety factors related to the inconsistent conduct of ship’s drills and Port Kembla’s emergency response plans.

Read the report: Fire on board Iron Chieftain, Port Kembla, New South Wales, on 18 June 2018

Key points:

• Student pilot initiated a low-level go-around;
• Aircraft deviated from the runway centreline, stalled and commenced a spin, before impacting the ground;
• Student pilot had very limited experience in the Bristell aircraft type;
• Flying school’s flight dispatch procedures were not followed.

The student pilot of a Bristell aircraft that stalled and commenced a spin before colliding with the ground was not authorised to conduct the flight and did not have the necessary qualifications and skills to safely operate the aircraft, an ATSB investigation has found.

The student pilot had departed Melbourne’s Moorabbin Airport on the morning of 12 December 2019 to conduct a series of circuits in the Bristell in what was their first solo flight in the aircraft type.

Just after crossing the runway threshold for the first touch-and-go landing, witnesses observed the aircraft suddenly pitch up. The left wing then dropped, bank angle increased to the point where the aircraft became inverted, and the aircraft entered the first half rotation of a spin entry. The aircraft’s nose then dropped before it impacted the ground adjacent to a taxiway in a steep inverted attitude.

The student pilot was severely injured in the accident, and the aircraft was substantially damaged.

The ATSB’s investigation found that the pilot commenced a go‑around at low level when the aircraft deviated from the runway centreline in a crosswind (the crosswind component was subsequently calculated to be about 13 kt, within aircraft performance limitations).

During the go‑around, the aircraft aerodynamically stalled and commenced a spin.

“The ATSB identified that the student pilot did not have the necessary qualifications and skills to safely operate the Bristell aircraft solo,” said ATSB Director Transport Safety Stuart Macleod.

“The student had undertaken only one supervised training flight in the Bristell, and that flight, which was curtailed due to deteriorating weather conditions, did not include any go-arounds, crosswind landings or stall training.

“Consequently, the student pilot’s familiarity with the Bristell was very limited.”

All the student’s previous flying had been undertaken in the Aeropakt A-32 Vixxen, a lower-performance aircraft with a different configuration and handling characteristics compared to the Bristell.

“The Bristell exhibits different handling characteristics to the other aircraft type the student pilot had previously operated,” said Mr Macleod.

“Specifically, instructors reported that the Bristell is less docile and has a stronger tendency to pitch up when engine power is applied for a go-around.

“Instructors also reported that the Bristell has less elevator authority to counter the nose-up effect and a greater tendency to drop a wing during a stall.”

Even though the student pilot believed they were instructed, and authorised, to conduct a solo flight in the Bristell, the ATSB found that the student pilot did not follow the operator’s solo flight dispatch procedures, including not endorsing the aircraft’s maintenance release, and not undertaking the required solo flight briefing and sign out procedure with a flight instructor.

“Familiarity with an aircraft’s specific systems, controls, handling and limitations is essential for safe flight,” said Mr Macleod.

“That is why safety-critical procedures and regulations are in place to ensure that pilots have the required level of skill and experience to safely operate an aircraft.

“The outcome of this accident, which could just as easily have been fatal, illustrates the potential consequences of deviating from safety-critical procedures and regulations.”

Subsequent to the accident, the flying school operator, Soar Aviation, advised the ATSB that they had revised procedures to ensure an aircraft could not be taken by a student for a solo flight, either deliberately or inadvertently.

The flying school ceased operations in December 2020.

Read the final report: Loss of control and collision with terrain involving BRM Aero Bristell S-LSA aircraft, VH-YVF, Moorabbin Airport, Victoria, on 12 December 2019

Key points:

• Two separate landing gear failures during beach landings involved the same aircraft;
• Maintenance inspections probably would have detected faults that led to the failures;
• Investigation highlights that operators should consider additional inspections when operating aircraft in challenging conditions, in addition to ensuring they are conducting the required inspections in accordance with the manufacturer’s maintenance schedule.

Two separate right main landing gear failures involving the same Gippsland Aeronautics GA8 Airvan during beach landings on Fraser Island, Queensland highlight the need to not only conduct required inspections in line with the manufacturer’s maintenance schedule, but that operators consider additional inspections when routinely operating aircraft in challenging conditions.

In both instances – a right main landing gear collapse on 24 August 2019 and a right main wheel and axle separation on 31 October 2019 – it is probable that the faults that led to the failures were detectable during recent maintenance activity on the aircraft, an ATSB investigation found. Neither incident resulted in injuries. 

In the August 2019 incident the right main landing gear collapsed when a number of the eight mounting bolts securing the landing gear loosened and wound out, placing excessive loads on the remaining bolts causing them to eventually shear and the landing gear leg to collapse. 

Although the unsecured bolts would have been apparent during one or more periodic inspections, the investigation found recent maintenance had not detected any problems.

The 31 October landing gear failure occurred when, during the landing roll, the right main wheel and axle separated from the landing gear at slow speed. The ATSB’s investigation noted that surface contamination and corrosion in the axle inspection area indicated that the required pre-inspection cleaning had not been conducted for an extended period, decreasing the likelihood of any visual identification of cracking.

An inspection 27 flight hours before the second occurrence did not detect fatigue cracking at the main landing gear axle attach sleeve that led to the axle failure.

Further, the required axle magnetic partial inspection was about 470 flight hours overdue at the time of the axle failure.

“The operator’s aircraft experienced increased loads on the landing gear in operating from beach landing areas on Fraser Island as frequently as 20–30 times a day,” ATSB Director Transport Safety Dr Mike Walker said.

“In this challenging salt-laden and humid environment, the ATSB concluded that the operator did not place appropriate emphasis on ensuring the continuing airworthiness of the landing gear of its GA8 Airvan aircraft fleet.”

Following the two incidents, the operator, Air Fraser Island, appointed a new head of aircraft airworthiness and maintenance control, employed a quality assurance officer to audit its maintenance system, and made changes to the personnel conducting maintenance on its aircraft.

“Operators routinely conducting operations to beach landing areas should ensure that they are conducting the required inspections in accordance with the manufacturer’s maintenance schedule and procedures as a minimum standard," Dr Walker said.

“They should also consider improved and additional inspections when frequently operating aircraft in challenging conditions.”

Read the final report: Landing gear failures involving a GA8 Airvan, VH-BFS, Fraser Island, Queensland, on 24 August 2019 and 31 October 2019

The flight crew of a Boeing 767 freighter did not consult the minimum equipment list (MEL) and continued their departure from Auckland Airport on a scheduled service to Sydney following a fuel configuration advisory alert message as the aircraft approached the departure runway, an ATSB investigation found.  

The flight crew, consisting of the captain as pilot monitoring and the first officer as pilot flying, commenced duty at about 9:30 am on 27 July 2017 for a 11:45 am departure. After completion of engine start at 11:40 am, the fuel panel was correctly configured with fuel distributed as 6.6 t and 6.5 t in the left and right main tanks and 7.9 t in the main centre tank.

While taxiing for departure, an imbalance developed in the fuel load between the left and right main tanks while the centre tank was providing fuel to both engines, triggering a fuel configuration EICAS (Engine Indication and Crew Alerting System) advisory alert message just after completion of departure procedures and receipt of clearance to enter the runway.

After determining a fuel leak was not the cause of the imbalance and confirming that the fuel panel was correctly configured the flight crew began the non-normal checklist and decided to continue with the departure and address the fuel imbalance condition in-flight.

Early in the climb the first officer identified the fuel imbalance was the result of abnormal operation of the fuel system, resulting in fuel from the centre tank being distributed to the right tank. Not wanting to trigger another advisory alert the crew decided to delay the fuel rebalancing until the centre tank was empty.

The crew completed the fuel configuration non-normal checklist about 30 minutes after departure, during which time the fuel imbalanced increased past the operator’s fuel imbalance limit. The left and right fuel tanks were successfully re-balanced and remained in balance for the rest of the flight.

On arrival in Sydney, the crew verbally reported the abnormal fuel system behaviour to the dispatch maintenance engineer in Auckland and the maintenance engineer, but it was not entered into the technical fault log.

ATSB Director Transport Safety, Stuart Macleod, said that in making their decision to depart the crew had considered a number of factors including the likelihood of a fuel leak and the low priority of the alert advisory message but had not considered the MEL following the EICAS alert.

“The flight crew had differing knowledge of the MEL requirements following a fuel configuration alert message, and this combined with a shared belief that the risk was low enough for the flight to proceed and having only consulted the non‑normal checklist, led them to believe they were able to depart,” he said.   

Mr Macleod said the occurrence highlights the importance of flight crews being fully conversant with all operating procedures, particularly those related to aircraft unserviceability that are critical to the safety of flight operations.

“Had the crew consulted the MEL they would have seen the requirement to return to the gate and seek maintenance action before continuing operations of the aircraft,” he said.

“In addition, delaying the completion of the non-normal checklist resulted in the fuel imbalance increasing to 2.6 t in excess of the operator’s fuel imbalance limitations, unnecessarily elevating the flight’s safety risk.”

The investigation report explains that the fuel imbalance was the result of abnormal fuel system behaviour, probably caused by the malfunction of one of the three fuel system valves, resulting in fuel from the centre tank being fed into the right main tank. Maintenance action was unable to determine to the cause of the malfunction.

Mr Macleod said the investigation also highlighted the importance of any aircraft unserviceability being recorded in the aircraft’s technical log to ensure that it is addressed and to provide future reference in case of further, or related, instances.

“Not entering the abnormal fuel system behaviour in the aircraft’s technical fault log resulted in a delay to maintenance action until after a further two sectors had been flown by the aircraft and probably hampered in the identification of the underlying fault.”

In response to the occurrence, the operator, Tasman Cargo Airlines, has undertaken to amend its MEL to clarify crew actions in the event of an EICAS message between off‑blocks and take-off.

Read the final report: Fuel imbalance involving Boeing 767, VH-EXZ, during flight from Auckland, New Zealand to Sydney, New South Wales, on 27 July 2019

Key points:

• Train driver read through to a green signal on an adjacent line, resulting in a signal passed at danger;
• Habituation limited the effectiveness of the automatic warning system in warning the driver of approaching a red signal;
• Investigation found discrepancies in rail operator’s train diver maintenance of competencies (MOC) process;
• Processes for maintaining and assessing the competence of rail safety workers should be effectively monitored and reviewed.

An emergency ‘STOP’ command issued by a network control officer avoided the potential for collision between two Brisbane suburban passenger trains following a signal passed at danger (SPAD) incident, with the subsequent ATSB investigation highlighting the importance of assuring train driver competence and having sophisticated engineering controls in place to manage the risks of SPADs.  

Queensland Rail (QR) Citytrain passenger service TP43 had just departed Bowen Hills station after a driver change on 10 January 2018, with the departure signal at the northern end of the platform displaying a yellow aspect, denoting that the next signal (ME45) would be set at red. As the train approached that signal, the driver mistakenly read through to a green aspect signal for an adjacent line, the ATSB investigation found.

Approaching signal ME45, the automatic warning system generated an alarm in the train driver cab, indicating the signal was at danger, which, if the driver did not acknowledge, would have triggered an emergency brake application. The driver acknowledged the alarm by pressing the reset button, but that acknowledgement was almost certainly an automatic response and did not result in the driver effectively checking signal ME45.

The train subsequently passed signal ME45 and exceeded its limit of authority. This generated a SPAD alarm at QR’s rail management centre, resulting in a network control officer broadcasting an emergency stop command to the driver via the train radio.

The driver responded to the command and stopped the train 220 metres past signal ME45, and 126 metres short of a crossover and conflict point. At the time that TP43 came to a stop, another suburban passenger train had just cleared the conflict point.    

Although the ATSB found the driver probably misread the green aspect signal on the adjacent line, the investigation also identified issues with the automatic warning system, and with QR’s administration of its train driver maintenance of competency (MOC) process, ATSB Director Transport Safety Dr Mike Walker said.

The automatic warning system provided the same alarm for all restricted signals, whether double yellow, yellow, flashing yellow and red, creating the potential for habituation, Dr Walker noted.

“Citytrain drivers frequently encounter restricted signals, and so it is understandable how drivers can become conditioned to cancelling the automatic warning system alarm as a habitual, reflexive reaction,” he said.

“The absence of a higher priority alert when approaching a signal displaying a red aspect reduces the effectiveness of the automatic warning system to prevent SPADs.

“That increases the reliance on procedural or administrative controls to prevent SPADs, which are fundamentally limited in their effectiveness.”

The investigation also found that limitations with QR’s administration of the Citytrain driver maintenance of competency process, which involved each driver completing a written and practical assessment every 18 months (or 12 months after first qualifying), provided limited assurance that its drivers met relevant competency requirements, Dr Walker said.

“In assessments undertaken subsequent to the SPAD incident, the very experienced train driver was found not to have met the relevant competency requirements even though their previous maintenance of competency assessments showed no indications of any problems,” he said.

“Further, QR’s management oversight of the Citytrain driver MOC process did not include planned assurance activities or regular and effective auditing of how the MOC assessments were being conducted, even after there were multiple indications that the process could have been undermined by not being conducted as designed.”

Dr Walker noted that QR has subsequently undertaken a range of proactive safety actions to address the design and implementation of its train driver MOC process.

“This investigation highlights the importance for rail organisations to have an assurance system in place that effectively monitors and reviews processes for maintaining and assessing the competence of train drivers and other rail safety workers,” he stated.

“Those assurance activities must be suitably designed and implemented to ensure that they appropriately evaluate controls that manage risk.”

In addition, the investigation notes that limitations with the automatic warning system in preventing SPADs remain.

“There is only limited potential to redesign the existing automatic warning system to reduce the risk of SPADs,” Dr Walker said.

The ATSB notes that QR is introducing the European Train Control System, which will provide more sophisticated controls for detecting SPADs, however that system is only being implemented across parts of QR’s south-east network.

“This occurrence highlights the importance for suburban passenger rail networks to have sophisticated engineering controls in place to detect potential or actual SPADs and manage their risk,” Dr Walker said.

“In addition, even though SPADs are rare events for most drivers, the role of driver performance in minimising the risk of SPADs is critical. This investigation provides an opportunity for train drivers to reflect on the need for crosschecking signal information, particularly at locations where there is potential for a signal read-through.”

Dr Walker also noted that the ATSB identified safety issues with QR’s implementation of risk triggered commentary driving (RTCD), as well as the limited use of recorded data to determine driver compliance with key operational rules that had been designed to minimise the risk of SPADs.

Read the final report: Signal ME45 passed at danger involving suburban passenger train TP43 and near collision with another suburban passenger train, Bowen Hills, Queensland, on 10 January 2018

Key points: 

• A380 flight crew misheard ATC instruction, aircraft turned left instead of right
• Flight crew likely experiencing a high workload due conducting a missed approach after experiencing windshear
• In instructing a second aircraft on approach to land on a parallel runway to turn right, the second aircraft experienced a loss of separation with a third aircraft

The pilots of an Airbus A380 which turned left instead of right while conducting a missed approach to land at Sydney Airport, contrary to an air traffic control (ATC) instruction, were likely experiencing a high workload, an ATSB investigation found.

The Singapore Airlines A380 was operating a scheduled passenger service from Singapore to Sydney on 9 February 2020, with the flight crew—comprising the captain as pilot flying and the first officer as pilot not flying—having briefed before and during the flight on the forecast deteriorating weather at Sydney. Cleared for an ILS (instrument landing system) approach to Sydney Airport’s runway 16 right, the A380 encountered windershear while descending through about 1,000 feet. In response, the flight crew initiated a missed approach and advised air traffic control that they were ‘going around due to windshear’.

Air traffic control instructed the flight crew to turn right onto a heading of 270°. The first officer read back the heading, however, did not include the direction of the turn, and ATC did not correct the incomplete readback. The flight crew then commenced turning the aircraft left instead of right.

Air traffic control subsequently issued a safety alert to the A380 flight crew, advised them of a Bombardier Dash 8 (DHC-8) aircraft about 6 NM (11 km) on final for runway 16 left, and instructed them to turn right and climb immediately. Air traffic control then instructed the flight crew of the Dash 8 to make a right turn in order to maintain separation with the A380. This in turn resulted in a loss of separation between the Dash 8 and a Boeing 737, which was on approach to runway 16 right.

The minimum distance between the Dash 8 and 737 aircraft reduced to 2.6 NM (4.8 km) laterally and 1,300 feet (397 m) vertically.

“The ATSB found that the A380 flight crew were likely experiencing a high workload managing a high-energy aircraft state as a result of conducting the windshear recovery and missed approach,” said ATSB acting Director Transport Safety Kerri Hughes.

“This, in combination with an expectation that they would be turning left, contributed to the flight crew mishearing the ATC instruction to turn right.”

Ms Hughes said the incident highlights the importance of readbacks to provide assurance that air traffic control instructions are correctly understood.  

“The flight crew omitted the direction of the turn from their readback, which was not corrected by ATC. This was a missed opportunity to correct the misheard instruction,” she said.

“This incident highlights the importance of flight crew completing full readbacks, as well as controllers correcting any readback discrepancies immediately.”

In response to the incident, Singapore Airlines issued a notice to flight crew, highlighting strategies to manage high workload situations, as well as reiterating the importance of correct readbacks and acknowledgement from ATC.

Read the final report: Operational non-compliance involving Airbus A380, 9V-SKQ, near Sydney Airport, New South Wales, on 9 February 2020

Key points: 

• All crew members began feeling unwell on second flight of the day
• Pilot observed indications of elevated levels of CO on chemical spot detector
• Crew immediately opened windows and confirmed cabin heating was off, but their condition deteriorated
• The pilot alerted air traffic control and landed safely as soon as possible

The crew of a Cessna 172 conducting an aerial shark patrol experienced symptoms associated with carbon monoxide exposure, highlighting the dangers of this colourless and odourless gas found in piston-engine aircraft exhausts, an ATSB investigation notes.

The aircraft with a crew of three, comprising a pilot, communications officer and observer, had departed Adelaide’s Parafield Airport for a second aerial shark patrol at 1.30 pm on 22 December 2019.

While overhead Sellicks Beach, about two hours into the flight, the communications officer and then the pilot became sick. They initially dismissed their symptoms as being due to turbulence, but the pilot subsequently observed a localised discolouration on the aircraft’s disposable carbon monoxide chemical spot detector. The communications officer, in the front right seat, confirmed the discolouration and the crew confirmed they were all feeling light-headed.

The crew immediately opened the aircraft’s windows and confirmed the heating was off, however the pilot’s condition worsened and they reported losing periods of time, loss of feeling in their legs, chest pains, and a tingling sensation in their hands.

With support from air traffic control, the pilot was able to return the aircraft to, and land safely at Parafield Airport, despite experiencing increased light-headedness and ongoing confusion.

On landing, the crew were then taken to hospital for medical examinations. Blood test confirmed they had mildly elevated carboxyhaemoglobin levels.

“Despite having only mildly elevated carboxyhaemoglobin levels, the crew’s physical symptoms and cognitive effects likely resulted from exposure to elevated CO levels in the aircraft cabin,” said ATSB acting Director Transport Safety Kerri Hughes.

“Owners and operators of piston-engine aircraft are strongly encouraged to install active warning CO detectors to alert pilots to the presence of CO before it adversely affects their ability to control the aircraft or become incapacitated,” said Ms Hughes.

“Further, once they experience any smell or sensation of illness pilots should check their CO detector, ensure cabin heat is off, open all fresh air vents and windows, and make a prompt decision to land using all available resources for assistance – such as contacting air traffic control – to do this safely.”

In this incident, the CO source within the aircraft could not be established, Ms Hughes noted. There were no indications of a potential exhaust leak prior to the flight and the post-flight testing found no fault with the aircraft. However, the most likely source of CO was from the aircraft.  

For more information on the use of active warning CO detectors read the ATSB’s recent safety advisory notice: Are you protected from carbon monoxide poisoning?

Read the final report: Partial crew incapacitation involving Cessna 172, VH-YXZ, 44 km south of Adelaide Airport, South Australia, on 22 December 2019

Key points: 

• Aircraft was conducting a post-maintenance check flight
• Wreckage examination found no evidence of pre-existing defects with the aircraft’s flight controls or structure
• Fuel system components including the fuel flow indicator were recovered from the site for further examination

The ATSB will continue its examination of recovered components and the analysis of downloaded recorded data as part of its on-going investigation into the fatal accident involving a Dynaero MCR-01 light aircraft near Serpentine Airfield, south of Perth, on 28 December 2020.

The aircraft, with the pilot the sole occupant on-board, had departed Serpentine’s runway 09 at about 1438 local time to conduct a second post-maintenance check flight. Shortly after take-off, at about 300 feet above ground level, witnesses heard an audible change in the aircraft’s engine noise.

The preliminary report notes that the aircraft was then observed to make a slow turn to the left. A further change in engine noise was then heard before the left wing dropped and the aircraft was seen to enter a steep, nose-down rotating descent. The pilot was unable to recover the aircraft before it impacted the ground in relatively flat, open farmland about 200 metres east of the threshold of Serpentine’s runway 23.

The pilot sustained fatal injuries, and the aircraft was destroyed.

“To date, ATSB transport safety investigators have examined the accident site and aircraft wreckage, interviewed witnesses, and retrieved aircraft components for further examination. The retrieved components include a damaged GPS unit, aircraft instrumentation, the engine, propeller and fuel system components including the fuel flow indicator,” said ATSB Director Transport Safety Dr Mike Walker.

“No pre-impact defects were identified with the aircraft’s flight controls or structure,” Dr Walker noted.

“In addition, the aircraft’s fuel tank had ruptured, and a quantity of fuel had leaked into the soil.”

Dr Walker noted the preliminary report does not include any safety findings or analysis, which will be detailed in the investigation’s final report.

“As well as the analysis of data from the aircraft’s fuel flow meter and other electronic devices, and considering witness information, the ATSB’s investigation will examine the recovered aircraft components and review the aircraft’s maintenance history and flight characteristics,” he said.

A final report will be released at the conclusion of the investigation.

“However, should a critical safety issue be identified during the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken,” Dr Walker noted.

Read the preliminary report: Partial power loss and collision with terrain involving Dynaero MCR-01 VLA, VH-SIP, near Serpentine Airfield, Western Australia, on 28 December 2020

Key points:

• Dash 8 surveillance aircraft’s engine failed on take off
• Power turbine shaft of the aircraft's right engine fractured due to fatigue cracking
• Corrosion pitting that exceeds repair limits on safety‑critical components should be a warning sign to manufacturers, maintainers, and operators

Corrosion pitting from prolonged low-altitude operations in a marine environment probably contributed to a Dash 8 surveillance aircraft’s engine failure on take-off, an Australian Transport Safety Bureau (ATSB) investigation has found.

The Surveillance Australia operated Bombardier DHC-8-315 aircraft with four crew on board was about to start its take-off roll from Darwin Airport on 11 November 2019. With the brakes on, power was applied to both engines. On reaching take-off power, and prior to brakes release, the crew heard a loud bang. The crew aborted the take-off and shut down the engine, while air traffic control advised the crew of smoke from the right engine.

After the aircraft had returned to the maintenance hangar, a runway inspection identified metal fragments behind the aircraft’s take-off position. An external inspection of the right engine revealed significant damage to the power turbine assembly.

“The ATSB’s investigation found that the power turbine shaft of the aircraft's right engine fractured due to fatigue cracking, resulting in secondary damage and engine failure,” said ATSB Director Transport Safety Stuart Macleod.

“The fatigue cracking initiated at corrosion pitting, which was probably associated with prolonged low‑altitude operation in a marine environment.”

The power turbine shaft originally installed in the engine was replaced during its first overhaul in 2011 due to excessive corrosion pitting. However, the maintenance organisation did not escalate the finding of corrosion to the engine manufacturer, Pratt & Whitney Canada (P&WC), possibly due to the informal reporting process at the time (formal guidance and criteria for reporting such findings was established in 2018).

The ATSB also identified that the power turbine shaft in P&WC PW100 series engines operating in certain marine environments is susceptible to corrosion pitting, which can grow undetected between scheduled inspections, increasing the risk of shaft fracture and engine failure.

“The corrosion-related fracture of the power turbine shaft of the aircraft’s engine in this occurrence highlights that corrosion pitting that exceeds repair limits on safety‑critical components should be a warning sign to manufacturers, maintainers, and operators that the existing maintenance strategy may not be effective,” said Mr Macleod.

“Additionally, manufacturers should provide guidance and criteria to maintenance organisations for assessing and reporting corrosion on safety‑critical components. This enables identification of whether the maintenance strategy is effective or if changes are required to reduce the risk of in‑service failures.”

P&WC has advised the ATSB it has commenced a review of historical overhaul experience of the power turbine shaft in an effort to identify which engines and operators are potentially exposed to an increased risk of shaft corrosion.

Additionally, P&WC has also proposed a range of safety actions to address the identified safety issue concerning the corrosion-related fracture of power turbine shafts in PW100 series engines that should complement its formalised reporting process. This includes considering a borescope inspection of the power turbine shaft between overhauls during hot section inspections with defined corrosion inspection criteria and investigating a method to remove contaminants from inside the shaft during service. Additional mitigating action for engines within the PW100 engine fleet that have completed hot section inspections, but are potentially exposed to the risk of power turbine shaft corrosion, is also being assessed. 

“While the proposed actions should address the safety issue, no timeline for their implementation was provided. As such, the ATSB has issued a safety recommendation to P&WC to support its proposed actions to avoid a similar shaft fracture from occurring,” said Mr Macleod.

Read the final report: Engine failure during take-off involving Bombardier Dash 8, VH-ZZE, at Darwin Airport, Northern Territory, on 11 November 2019

Key points:

• The investigation identified a safety issue relating to lack of post-training supervision by the helicopter operator
• Shortly after being trained in powerline stringing operations, for unknown reasons, the pilot modified the stringing methodology
• Experience alone will not always prevent a pilot from having an accident

An Australian Transport Safety Bureau (ATSB) investigation into an accident where a Squirrel helicopter struck a powerline pole identified that the operator’s procedures had no requirements to provide any post-training supervision for powerline operations, and that what supervision was provided was ineffective in identifying that the pilot was using a modified stringing method.

The AS350B3e Squirrel helicopter, registered VH-SZS and operated by Aeropower, was stringing powerlines from the Mount Gunson South substation to the Carrapateena mine site, a total distance of 51 kilometres, approximately 60 kilometres east of Woomera Airfield, South Australia on 20 March 2019.

While pulling the draw wire with a nose-high and rearward attitude, the helicopter’s main rotor blades struck the pole about 17 metres above the ground. The helicopter subsequently impacted the ground near the base of the pole.

Several ground crew from the stringing team extinguished a small post-impact fire and removed the pilot from the aircraft to a safe distance. A short time later emergency services and paramedics from the mine site attended the scene and confirmed that the pilot, who was the sole occupant, had received fatal injuries. The helicopter was destroyed.

Shortly after being trained in powerline stringing operations, for unknown reasons, the pilot modified the stringing methodology. In addition to placing the helicopter at low level in the vicinity of the powerline poles, the modified methodology also exacerbated the uptake of dust. This, in combination with the position of the sun and the rearward attitude of the helicopter, likely reduced the pilots’ visibility of the pole and their situational awareness of it.

“There were no requirements in the operator's procedures to provide any post-training supervision for powerline operations,” Director Transport Safety Stuart Macleod said.

“What supervision was provided was ineffective in identifying that a modified stringing method was being used by the pilot.”

In November 2020, the ATSB were advised that Aeropower had taken a number of proactive safety actions specifically relating to the supervision and review of newly authorised pilots in specialist tasks.

“These actions taken by Aeropower address the key concern of the investigation's identified Safety Issue, being the supervision of pilots recently trained or authorised in a new specialist task,” Mr Macleod said.

“The mandated extension of command under supervision time, the introduction of periodic consolidation flight checks, and the mandated extension of mentoring time are all expected help better prepare newly trained pilots for solo operations and provide them with additional defences to the hazards associated with specialist flight tasks.”

The investigation also highlighted that experience alone will not always prevent a pilot from having an accident. In this case, the pilot was a very experienced deputy chief pilot with nearly 6,500 flight hours.

Research published by the ATSB in 2012 as part of its Avoidable Accidents series titled Experience won't always save you, showed experience does not always provide a safeguard.

“Using pilot experience as mitigation for potential operational risks is inadvisable," Mr Macleod said.

“The ATSB has found that in some occurrences very experienced pilots were undertaking flying that involved much higher risk. And as a consequence, we found that in those circumstances their flying experience alone was unable to help them avoid an accident.”

Read the final report: Collision with terrain involving AS350, VH-SZS, 60 km east of Woomera, South Australia, on 20 March 2019