The Australian Transport Safety Bureau has released the final report from its investigation into the collision with water of a Cessna 182 light aircraft near Moreton Island. 

The Cessna 182Q aircraft had departed Caloundra Airport at around 3:30pm on 22 January 2020 for a private sightseeing flight over Moreton Island and Flinders Reef, with a pilot and passenger on- board. 

Recorded air traffic control radar data from the flight indicated that the aircraft flew along Moreton Island’s eastern coastline, from south to north, at 1,400—1,500 ft above sea level. 

The aircraft then commenced a shallow descent before passing Cape Moreton, at the northern tip of the island, at about 1,300 ft, continuing north-east towards Flinders Reef.  

The aircraft rate of descent began to increase, and after approximately 90 seconds, the pilot made a MAYDAY call that identified the aircraft’s callsign but not its position nor the nature of the emergency. 

At the time of the MAYDAY, the aircraft was east of Flinders Reef and descending through 300 ft, with a groundspeed of about 115 kt (213 km/h). The aircraft continued north-east for 15–20 seconds, before colliding with water at 4:26pm. 

On 29 January the aircraft wreckage was found on the ocean floor at a depth of about 30 m, and about 45 m from the estimated point of impact with water. The pilot and passenger were not located. 

On the evidence available, the nature of any in-flight emergency or abnormal situation, and any effect it had on the pilot’s ability to control and configure the aircraft for a ditching on the water, could not be established. 

Examination of the wreckage indicated the aircraft was likely destroyed by the collision with water at a moderately high speed and there was no evidence of pre-impact defects or structural failure. 

“ATSB investigators found that the engine’s power was reducing over the last period of the flight, for about 100 seconds,” noted ATSB Director Transport Safety Dr Mike Walker. 

At the time of the accident flight, weather conditions were conducive to carburettor icing, which is common in the region. The ice build-up within an aircraft engine’s carburettor may result in reduced power output, poor engine performance, rough running, and in extreme cases engine failure. The risk of carburettor icing is significantly increased at partial power settings (for example, when power is reduced during descent), because of the cooling effect of a partly-closed throttle. 

“The likely reduction in power in the last 100 seconds of recorded flight could plausibly have been due to carburettor icing,” Dr Walker observed.  

“However, a conclusion regarding the possible influence of carburettor icing on the development of the accident could not be drawn with any certainty. 

“Carburettor icing conditions are frequently encountered in the region, and carburettor icing can be easily prevented and managed through the use of carburettor heating.” 

During the accident flight, the aircraft maintained course away from suitable landing areas at a speed well above the aircraft’s best glide speed.  

Although the reduction in power and resulting descent would have been indicated on the aircraft’s instruments, the pilot may have been initially unaware of it because there would have been little or no change in sound and feel. 

The investigation also found that the pilot had twice descended over water beyond the glide range of a suitable landing area on a previous flight. 

“Although it could not be determined whether the aircraft’s descent out of glide range during the accident flight was intentional, pilots are reminded that the operation of single engine aircraft over water should at all times be conducted with consideration of the aircraft’s glide distance to a suitable landing area,” said Dr Walker. 

“Descending over water beyond the glide range of a suitable landing limits a pilot’s options to conduct a forced landing in the event of an emergency, such as an engine failure or partial power loss.” 

Read the final report: Collision with water involving Cessna 182, VH-WNR, 6 km north-west of Moreton Island, Queensland, on 22 January 2020

The Australian Transport Safety Bureau (ATSB) advises all pilots, operators and maintainers of recently-built Robinson R22 and R44 helicopters to monitor for intermittent or abnormal operations of the helicopters’ engine RPM governor, which can lead to engine overspeed or underspeed conditions.

A small number of recent incidents have been reported to both the ATSB and to the Civil Aviation Safety Authority (CASA) where the governor has not controlled engine RPM under normal conditions.

“This has led to either a rotor overspeed or underspeed condition, requiring the pilot to override the governor by applying collective throttle inputs,” noted ATSB Chief Commissioner Angus Mitchell.

“The ATSB encourages all pilots, operators and maintainers of R22 and R44s purchased after 15 January 2020 to familiarise themselves with CASA’s recently-released airworthiness bulletin(Opens in a new tab/window), and to continue to report such instances via the CASA Defect Report Service portal,” he said.

“In addition, any incidents where the safety of flight is affected should also be reported directly to the ATSB.”

The engine RPM governor senses engine RPM and makes adjustments to the throttle control to maintain a constant engine RPM, which leads to a constant rotor RPM in flight, and it may not prevent over or under speed conditions during aggressive manoeuvres.

“As per the CASA AWB, pilots are encouraged to exercise care not to unintentionally override the governor by squeezing the throttle twist grip too tightly, and to monitor governor operation during flight by keeping their hand lightly on the throttle twist grip,” Mr Mitchell said.

“A properly-functioning governor will provide relatively slow, small, and frequent twist grip rotation in both directions. If twist grip rotation becomes erratic or stops altogether, the governor may be malfunctioning.”

The AWB notes that if a governor malfunction is suspected, switch the governor off, assume manual RPM control using the twist grip, land as soon as practical, and have the governor serviced by qualified maintenance personnel.

The helicopter manufacturer, Robinson Helicopter Company, is currently investigating the circumstances of the malfunctions to identify causal factors and solutions.

Key points:

• Two banking locomotives began to roll away from the train crew after their parking brakes failed; 
• The two train crew boarded the locomotives but were unable to take control, and a 3 km runaway occurred before a derailment, resulting in minor injuries; 
• Operator has subsequently modified the locomotive classes involved along with relevant procedures, and has developed resources to enable more effective training. 

A pair of banking locomotives rolled away and derailed during a change of ends at Ardglen bank in the NSW Hunter region after their parking brakes failed and the crew was unable to regain control, a transport safety investigation report details. 

On the evening of 3 June 2020, two Aurizon banking locomotives had just assisted a loaded coal train up the Ardglen bank when they came to a stop to prepare for a change of ends. 

While the two members of the train crew were transferring between the banking locomotives, the locomotives began to roll back down the Ardglen bank. The crew were able to board, but unable to take control of the locomotives. 

During the runaway event, the locomotives travelled approximately 3 km, and reached speeds of 114 km/h, before derailing and overturning on their side, and coming to a rest 13 m apart. 

The train crew sustained minor injuries in the accident and were able to exit the cabin. Both locomotives were significantly damaged, and about 100 m of track was damaged. 

An investigation into the incident was undertaken by the Office of Transport Safety Investigations (OTSI), which conducts rail safety investigations in NSW on behalf of the Australian Transport Safety Bureau. 

“During the process of changing ends, the driver likely depressed the independent brake handle accidentally, at the same time as placing the now-trailing locomotive into ‘Trail Cut-out’ mode,” OTSI Chief Investigator Dr Natalie Pelham explained.  

“This released the automatic air brake application on both locomotives.” 

The park brakes were then ineffective in holding the locomotives on the grade at Ardglen, and the banking locomotives started to roll away. 

“Rail transport operators should ensure parking brake systems on locomotives are effective, regularly inspected and maintained,” Dr Pelham said. 

The investigation found Aurizon’s relevant work instruction lacked specific detail about how to safely change ends – this information was included in the Operator’s Manual and also detailed in training documentation. 

“Without the step-by-step information being detailed in the work instruction, Aurizon’s system did not provide a clear ‘how to’ for safely changing ends,” Dr Pelham said. 

“Work instructions in quality management systems explain ‘how’ things need to be done. In this case, the work instruction detailed ‘what’ needed to be done, but the ‘how’ was left to the train crew to carry out based on what they could recall from their training.” 

The OTSI investigation also found that, during the runaway, the use of the forced lead function on the locomotives would likely have allowed the train crew to regain control, but the crew had not been trained to use this function. 

“Operators’ safety management systems should contain operational work instructions with sufficient detail on how to carry out safety critical tasks, like using the forced lead function,” Dr Pelham said. 

Since the incident, Aurizon completed an internal investigation, and commenced and completed several actions to prevent a recurrence. 

The operator completed modifications on the locomotive classes involved in the incident to improve alignment in the braking system, resulting in improved park brake force. 

It also modified the procedure clarifying steps for changing ends and when to use forced lead function and monitoring, and began monitoring the correct application of the procedure through regular analysis of locomotive downloads. 

Finally, the operator developed training resources to enable more effective training in emergency situations. 

Read the final report: Uncontrolled runaway and derailment of banking locomotives, Kankool, New South Wales, on 3 June 2020

New categories of aircraft operations, additional responsible persons, and harmonised definitions with domestic and international standards are drafted in proposed updates to Australia’s Transport Safety Investigation Regulations.

The ATSB is calling on its aviation, marine and rail stakeholders to take part in the consultation process to help shape the next update of Australia's Transport Safety Investigation (TSI) legislation.

Under the TSI Act, The TSI Regulations define what occurrences are reportable to the ATSB, how urgently they should be reported, what form a report must take, and who is responsible for making a report.

The ATSB has released an Exposure Draft and Consultation Paper detailing proposed amendments. This is towards finalising the new Regulations by mid-2022, for commencement at the start of 2023. 

The proposed changes have been prepared by the ATSB working closely with the Office of Parliamentary Counsel, and have been shaped by the ATSB’s ongoing work, a series of past consultations in 2019 and 2021, and continuous engagement with industry stakeholders.

“Broadly speaking, the proposed changes aim to bring transport safety investigation legislation in line with industry and international standards, and help the ATSB maximise its ability to improve transport safety, without placing undue burden on industry,” ATSB Chief Commissioner Angus Mitchell said.

Among the six issues discussed in the Consultation Paper is the proposed recategorisation of aircraft operations, to prioritise them in four distinct categories.

New, clear definitions for aircraft accidents and incidents would then prescribe what occurrences need to be immediately reported, or routinely reported, for each category of operation, with higher categorisations bearing a stricter reporting standard.

“The Statement of Expectations, provided to the ATSB by the Minister, makes it clear we should use our resources for the greatest public safety benefit,” Mr Mitchell said. 

“Ensuring the greatest focus is on receiving reports with the highest potential to improve safety, is in line with that directive.”

The proposed changes would also extend the persons who are responsible to report occurrences in the aviation and marine sectors.

In aviation, this would include sport aviation bodies and insurers of aircraft as responsible persons. In marine, pilotage providers and vessel traffic service authorities would be added.

“It’s important to note that, as with the existing framework, a responsible person only has to report an occurrence if they have a reasonable belief that no other responsible person has reported the matter,” Mr Mitchell noted.

“For example, if an aircraft is damaged in an incident, and the insurer receives assurance from the pilot that the occurrence has been reported, the insurer would not have to report that incident.

“But the goal of this change is to make sure that accountability is there, and ultimately reduce the number of occurrences that are not reported to the ATSB.”

One welcome proposal for all operators will be the extension of written reporting timeframes from within 72 hours to within 7 days. This will form part of a separate package of work to amend the TSI Act.

“This proposal relates to the written report, which follows the initial notification via telephone as soon as possible after an occurrence,” Mr Mitchell explained.

“Considering prior consultation and stakeholder engagement, the ATSB is of the view that a 7-day window to file a formal written report will maximise the quality of information that can be included, without sacrificing the recency necessary to ensure the information is current. If this proposal is supported by industry, we will work with government on making these changes.

“It is worth noting this will not change the existing pathways for reporting an incident to the ATSB; that is, through the Office of the National Rail Safety Regulator for rail occurrences, the Australian Maritime Safety Authority for marine occurrences, and directly to the ATSB for aviation occurrences,” Mr Mitchell added.

The Consultation Paper also explains a number of clarifications, minor and technical changes, proposed with the goal of better aligning the language of legislation to the other changes proposed in this consultation round. 

It also proposes prescribing the format for written reports, aligning with the Minister's Statement of Expectations by ensuring the ATSB can work efficiently to improve transport safety.

“I encourage all of our stakeholders to go to our website and check out the Consultation Paper and Exposure Draft for these proposed changes,” Mr Mitchell concluded.

“You can then take part in our consultation survey and give us the valuable feedback we need to finalise these changes.”

Consultation closes 7 March 2022. 

Review the Consultation Paper and other documents here.

Complete the consultation survey here(Opens in a new tab/window).

Key points:

• After nose wheel turning angle was unexpectedly restricted during taxiing, the captain opted to continue a turn, briefly exiting the runway area;
• In such an unexpected event where there is sufficient time to assess available options, flight crew are encouraged to utilise all available resources to determine the safest course of action.

Flight crews should utilise all available resources when they encounter unexpected events during taxiing, an Australian Transport Safety Bureau report into a taxiing excursion by an airliner at Laverton notes.

On the afternoon of 28 September 2021, a Fokker F100 aircraft, operated by Alliance Airlines, landed uneventfully at Laverton Airport, Western Australia, following a scheduled passenger flight from Perth, with 2 flight crew, 3 cabin crew, and 75 passengers on-board.

After completing the landing roll, the captain began to taxi the aircraft towards the end of the runway, intending to turn around and backtrack to the taxiway.

Upon reaching the end of the runway, the captain commenced a right turn by rotating the nose-wheel handwheel, or tiller. However, the captain was unable to achieve full tiller rotation, even when using the force of both hands.

They attempted to tighten the turn by applying the right inboard brake, and asymmetric thrust, but this did not have the desired effect.

“A torn boot on a universal joint probably restricted the operation of the aircraft’s nose-wheel steering system, preventing the aircraft from completing the turn on the runway,” ATSB Director Transport Safety Stuart Macleod explained.

Realising the aircraft would not be able to complete the turn without the nose-wheel leaving the runway surface, the captain decided to continue.

They later reported this decision was made based on their knowledge of the ground next to the runway being compact dirt, and the fact the airport had a single runway and no ground support equipment, so stopping would prohibit other aircraft from landing.

“In continuing the turn the nose-wheel left the runway surface and entered the runway strip, increasing the risk of damage to the aircraft,” Mr Macleod said.

“While there was no damage to the aircraft, there was no assurance that the runway strip was clear of hazardous debris and could safely manoeuvre on the strip.”

Mr Macleod noted that other aircraft would have been unable to safely land if the Fokker had remained on the runway.

“But options such as having the airport staff inspect the runway strip before completing the turn onto it were available,” Mr Macleod said.

“This incident highlights that when flight crews encounter an unexpected event and there is sufficient time to assess available options, they should utilise available resources to determine the safest course of action.”

After completing the turn and re-entering the runway, the captain taxied the aircraft to the terminal without incident.

A post-flight inspection identified damaged insulation in the nose-wheel area, and the torn universal joint boot on the tiller shaft.

Read the final report: Taxiing excursion involving Fokker F100, VH-FKD, Laverton Airport, Western Australia, on 28 September 2021

Key points:

• A NSW TrainLink service was stopped, and the train evacuated, after a small fire was detected at the rear;
• The fire was the result of a collapsed axle bearing, likely caused by locking plate tabs not being fitted correctly during a bogie overhaul;
• This occurrence emphasises the significance of having adequate bearing installation processes and ensuring that axle bearings are correctly maintained and monitored throughout their operational life.

A fire which led to the evacuation of a NSW TrainLink service at Yerrinbool in the New South Wales Southern Highlands was the result of a collapsed axle bearing, likely after locking plate tabs were not fitted correctly during a bogie overhaul, a transport safety investigation notes.

The two-car Endeavour train, crewed by a driver and train guard, and with approximately 20 passengers onboard, was operating service SN68 from Moss Vale to Campbelltown on the evening of 13 October 2020.

At 1820, as the train was slowing to stop at Yerrinbool Station, the guard inside the cab at the rear of the train heard a loud noise and noticed smoke outside the window. The guard then used the train’s bell system to ask the driver to stop.

The driver brought the train to a stand at Yerrinbool Station and the passengers were evacuated onto the platform.

After receiving permission from train control to access the track the driver attempted to extinguish the fire using an on-board extinguisher, but it continued to smoulder/burn before it was put out by Fire and Rescue NSW. There were no reported injuries.

Subsequent inspection determined that parts of the axle box were heat affected and sustained significant damage to the speed sensor and rubber suspension components.

An investigation into the incident was undertaken by the Office of Transport Safety Investigations (OTSI), which conducts rail safety investigations in NSW on behalf of the Australian Transport Safety Bureau.

The investigation determined the fire was the result of a collapsed axle bearing on wheel 8 on car 2811, the last on the train.

Approximately an hour before the fire, a wayside sensor at Burradoo had detected an elevated temperature, but the detection was below the threshold for an alarm to be sent to network control.

“The investigation determined the bearing failed when the axle end cap bolts loosened and one fractured, which caused the collapse of the bearing, resulting in frictional heat, and the fire,” OTSI Chef Investigator Dr Natalie Pelham said.

“The axle bearing installation process was not sufficient to ensure the tabs on the locking plate were installed correctly during a refurbishment three months before the incident.

“It is likely that during this last overhaul, the locking plate tabs retaining the axle end cap bolts were not fitted correctly against the sides of the bolts.”

Following the occurrence, Sydney Trains – which provides maintenance for NSW TrainLink – initiated an inspection of similar axle bogies in the fleet, and undertook an audit of the practices of the contracted maintainer, United Group Limited Unipart (UGLU).

“Sydney Trains has advised improvements have been made to UGLU’s quality assurance processes to ensure bolts and locking tabs are correctly installed,” Dr Pelham said.

Sydney Trains has also implemented an improved process to review and retain UGLU’s certificate of completion checklists.

“Bearing failures continue to occur within the Australian rail network,” Dr Pelham noted.

“This occurrence emphasises the significance of having adequate bearing installation processes and ensuring that axle bearings are correctly maintained and monitored throughout their operational life.”

Read the final report: Defective axle bearing leading to fire on passenger train SN68, Yerrinbool, New South Wales, on 13 October 2020

The pilot of a twin-engine Islander aircraft was attempting to exit south-west Tasmania’s Western Arthur Range in low visibility conditions when it collided with a ridgeline, an Australian Transport Safety Bureau investigation details.

The Airlines of Tasmania-operated aircraft was conducting a positioning flight under visual flight rules on the morning of 8 December 2018 from Hobart’s Cambridge Airport to an airstrip at Bathurst Harbour in the Southwest National Park. A single pilot was on board.

Satellite-based ADS-B transponder data from the aircraft showed that the pilot had tracked from Cambridge Airport direct to Bathurst Harbour, passing through a gap (or saddle) in the Arthur Range known as ‘the portals’, a route used in low cloud conditions.

After passing through the saddle, flight data showed the aircraft manoeuvred in a valley, consistent with the pilot assessing different options for possible routes through to Bathurst Harbour, before tracking back towards the portals, the investigation’s final report details.

While in a turn under power and pilot control, the aircraft collided with a ridge on the Western Arthur Range, at an elevation of about 885 m (2,805 ft). The aircraft was destroyed in the accident and the pilot was fatally injured.

“The ATSB’s investigation found that the pilot was using a route through the Arthur Range due to low cloud and had continued over a saddle in the range at a lower altitude than previous flights along the same route,” said ATSB Director Transport Safety Dr Stuart Godley.

“During this, the pilot likely encountered reduced visual cues, and while attempting to exit the range, the aircraft collided with a ridge that formed part of the Western Arthur range,” he said.

“For pilots, this tragic accident highlights the hazards associated with flying in mountainous terrain and the need to have an escape route. It also shows the challenges of in-flight weather-related decision‑making.”

The investigation also found that Airlines of Tasmania’s guidance to its pilots for operations to Bathurst Harbour was primarily given verbally and was not well documented.

“This resulted in the operator’s pilots having varied understandings of the expectations regarding in-flight weather-related decision-making at the Arthur Range saddle,” Dr Godley said.

The ATSB’s investigation also found that, while not a contributing factor to the accident, the operator’s safety management processes had limited opportunities to proactively identify risks in all operational activities and to assess the effectiveness of risk controls.

“For operators, this investigation highlights the importance of using multiple sources to identify the hazards potentially affecting the safety of their operations, rather than relying on one key source. These can include safety occurrence reports, inspections, audits, flight data, and expert judgment,” Dr Godley said.

“Likewise, it is equally important that operators monitor and evaluate the ongoing effectiveness of existing risk controls to ensure that they remain appropriate.”

Subsequent to the accident, in January 2020, Airlines of Tasmania introduced specific guidance for its south‑west Tasmanian operations, introducing visibility requirements for pilots using the direct route through the Arthur Range saddle.

In addition, the operator added further information and guidance to its training syllabus, and introduced changes to its safety management system.

The investigation notes the operator has also committed significant resources into installing technologies to assist with flight planning and oversight of its operations. This included the installation of a new high definition 360° webcam at the Bathurst Harbour airstrip and the installation of ADS-B ground receivers at a number of locations, including within the Southwest National Park.

Another aspect of the ATSB’s investigation was an analysis of the Civil Aviation Safety Authority (CASA)’s oversight of Airlines of Tasmania, including surveillance activities. The investigation found that, while not a contributing factor to the accident, CASA’s process for acquitting repeat safety findings was not effective. While there were ongoing communications with the operator, CASA did not conduct any formal surveillance activities specifically related to the operator's safety management system.

Finally, the investigation notes that, while ADS-B transponder data provided important information to the ATSB’s investigation, the aircraft was not fitted with an onboard recording device (nor was it required to be).

“An on-board recorder would have provided valuable information to better understand the pilot’s in-flight weather-related decision-making and identify potential safety issues,” Dr Godley said.

 “The use of lightweight recorders on smaller aircraft conducting commercial passenger operations can provide a relatively simple and cost-effective way of achieving of the benefits of traditional recorders fitted to large aircraft.”

Read the final report: VFR into IMC and controlled flight into terrain involving Pilatus Britten-Norman BN2A, VH-OBL, 98 km west-south-west of Hobart Airport, Tasmania, on 8 December 2018

A relief signaller who was working on two signal panels at once when they routed a train through a protected worksite was possibly experiencing the effects of cumulative fatigue as well as being under a high workload, a transport safety investigation report details.

On the evening of 15 October 2019, two Sydney Trains workers and a Protection Officer (PO) were conducting track work between Parramatta and Westmead stations, in Sydney’s west. 

Absolute Signal Blocking (ASB) was being used to protect the worksite, with the PO arranging with the signaller for a pair of signals to be set to stop to prevent trains from entering the section. 

However, the signaller directed an approaching passenger train to enter the section by removing the blocking for the two signals, with the intention of routing the train through a set of points to take it onto the adjacent track, to go around the track workers.

After passing the signals, the train driver saw the workers on the track in front of them, sounded the train whistle, and applied the emergency brakes. 

The workers were able to vacate the track and danger zone, as the train came to a stop near where the workers had been. 

An investigation into the incident was undertaken by the Office of Transport Safety Investigations (OTSI), which conducts rail safety investigations in NSW on behalf of the Australian Transport Safety Bureau. 

“The investigation found the relief signaller at Granville signal box had mistakenly believed the workers were further away from the location that was provided in the agreed arrangements for Absolute Signal Blocking,” OTSI Chief Investigator Dr Natalie Pelham said.  

“This mistaken belief led to the signal protection for the worksite being removed to allow a train to go around the workers using an alternative route.” 

The signaller and the PO had discussed the need to divert trains around the worksite, but neither had correctly comprehended the implications of doing this. 

“The relief signaller was possibly experiencing the effects of cumulative fatigue due to rostering issues as well as experiencing a high workload,” Dr Pelham said. 

The rostered signaller at the Granville signal panel was absent from their workstation at the time of the incident and the relief signaller was operating both the Granville and Westmead signal panels. 

“Sydney Trains did not provide suitable management arrangements for supervision at Granville signal box to ensure there was adequate coverage on both signalling panels,” Dr Pelham said. 

“Signallers are safety critical workers who perform work which is vital to the safe performance of the rail network.  

“These workers require supervision and should be subject to suitable management arrangements to ensure compliance to relevant work instructions and requirements.” 

The relevant Network Rules and Procedures for ASB had very little direction and guidance to workers about how to manage the risk of clearing a protecting signal for an alternative route in order to run a train, the investigation notes. 

“Railway safeworking rules are in place to achieve safe rail operations and should be developed so that the desired outcomes are supported by suitable procedures,” Dr Pelham noted. 

Sydney Trains temporarily prohibited the practice of signallers being permitted to clear any signals used for ASB protection in order to run trains via an alternative route. 

Subsequent changes to the ASB rule and procedure were implemented in December 2020 to prohibit the clearing of the signal immediately protecting a worksite in order to run a train via an alternative route. 

The investigation also found there were inconsistences with Sydney Trains’ application of their fatigue management system, in particular the use of a bio-mathematical model to predict individual fatigue risk. 

Read the final report: Near hit with workers on track using Absolute Signal Blocking, Westmead, New South Wales, on 15 October 2019

Key points:

• A helicopter pilot conducting long-line lifting operations sustained serious head injuries during a collision with terrain;
• ATSB investigation determined it was virtually certain the head injuries were the result of the pilot not wearing an upper torso restraint during the flight;
• Upper torso restraints are likely not fit-for-purpose for vertical reference flying, such as long-line lifting and aerial firefighting, and are likely not routinely worn by many pilots.

Aerial firefighting and long-line lifting helicopter pilots are often subjected to an elevated risk of serious injury, as standard upper torso restraints are not suitable for use during many of these operations, an Australian Transport Safety Bureau investigation highlights.

On 17 April 2018, the pilot of a Garlick Helicopters UH-1H ‘Huey’ helicopter, was conducting long-line lifting operations near Talbingo, in the Snowy Mountains region of New South Wales, to assist drilling works for the Snowy 2.0 project.

After 11 uneventful lifting runs between a drill site and a laydown area, the pilot was climbing clear of trees near the drill site, waiting for the next load to be ready.

As the helicopter started to climb, the pilot heard a loud mechanical ‘screaming’ noise and started planning for a forced landing. Witnesses also reported seeing ‘smoke’ and some advised they heard a ‘bang’ at about the same time.

Almost immediately, the pilot also heard an audible alarm, then experienced noticeable yaw and engine power loss.

Unable to determine if ground crew would be clear of the helicopter at the drill site clearing, the pilot opted instead to conduct the forced landing in the nearby Yarrangobilly riverbed to the south-west.

The helicopter subsequently collided with trees and the riverbed, and was destroyed. Ground personnel from the drill site immediately responded to the accident, extinguishing a small fire in the engine bay and removing the pilot from the wreckage.

The pilot was wearing a lapbelt and a helmet, but was not wearing the fitted upper torso restraint.

“It was virtually certain that this lack of upper torso restraint use resulted in the pilot sustaining serious head injuries when the aircraft collided with the riverbed,” ATSB Director Transport Safety Dr Stuart Godley said.

In Australia, vertical reference flying – when a pilot looks down as well as out to position the helicopter – mainly comprises aerial firefighting, and to a lesser extent, lifting operations.

During the ATSB investigation, it was identified that a notable proportion of pilots conducting vertical reference flying operations are likely not routinely wearing upper torso restraints.

“In the majority of helicopters used for vertical reference flying, the pilot often needs to be able to lean out to look below the helicopter to observe the line and load,” Dr Godley said.

“Standard upper torso restraints are likely not fit-for-purpose for these operations. This means, in the event of an accident, the restraints cannot provide the important defence to reduce the severity of injuries.

“Engineering innovations for these restraints could reduce the risk associated with this problem, which is particularly relevant in Australia during bushfire season, when the frequency of vertical reference flying is elevated.”

During the examination of the wreckage at the site, the ATSB identified cracking and material loss visible in the exhaust diffuser area.

The helicopter’s engine was sent to the manufacturer’s facilities in the United States, where it underwent a teardown examination.

“This examination revealed extensive fatigue cracking in the exhaust diffuser inner struts, which supports the rear of the power turbine assembly,” Dr Godley said.

“When these fatigue cracks led the engine exhaust diffuser inner struts to fracture, this resulted in a complete loss of engine power.”

It was determined this high-cycle metal fatigue had not been detected for at least 34 daily, and 2 phased maintenance inspections prior to the accident.

Although the helicopter’s engine failed close to the cleared drilling area, the pilot did not have assurance that ground support personnel could vacate the drill site in an emergency.

The ATSB found that the documented risk assessment for the helicopter’s lifting operations at the drill site operations did not consider the hazard of an emergency landing.

“This increased the risk that ground personnel were not clear of the load pick-up area in the event an emergency landing was required. In this accident, this lack of assurance led the pilot to conduct the forced landing to a less suitable location, increasing the severity of impact forces during the subsequent collision with terrain,” Dr Godley said.

Read the final report: Collision with terrain, Garlick Helicopters UH-1H, VH-HUE, 24 km south-east of Talbingo, New South Wales, on 17 April 2018

Piston engine helicopter pilots are reminded to be alert for unexpected yawing and transient reduced engine performance during flight, following an Australian Transport Safety Bureau investigation into the forced landing of a Robinson R22 near Geraldton earlier this year.

On the morning of 20 February 2021, a R22 Beta helicopter was to be repositioned from a storage depot near Geraldton Airport to Murchison House Station near Kalbarri, Western Australia.

Shortly after lifting off, at about 30-40 ft above the ground, the engine’s performance reduced, and the helicopter began to descend. The pilot completed a forced running landing in a yard adjacent to the point of departure.

“The ATSB found that an inlet valve in the engine’s number-four cylinder sustained thermal damage, which led to reduced engine performance, resulting in the forced landing,” ATSB Director Transport Safety Stuart Macleod explained.

A short time after the forced landing, the pilot elected to reposition the helicopter. However, on becoming airborne, the helicopter began to immediately rotate nose-right, and the pilot again landed the helicopter.

The ATSB investigation found that the loss of directional control was the result of a loss of drive from the helicopter’s tail rotor, due to a fracture in the tail rotor drive shaft close to its connection with the tail rotor gearbox.

“This incident serves as a reminder for all pilots of piston engine helicopters to be alert for unexpecting yawing during flight,” Mr Macleod said.

“Additionally, when a loss of engine power or abnormal operation is encountered, an appropriately licensed maintenance engineer should complete an engine cylinder inspection in accordance with the helicopter and engine manufacturer’s most recent service instructions, before any further flight takes place.”

The ATSB’s investigation also highlighted the utility of borescope inspections.

“Maintenance organisations should note that when completing a differential compression test of the engine cylinders, an accompanying borescope inspection of the cylinders and valves will provide an effective method to visually assess the condition of these components.”

Read the final report: Engine power loss and forced landing involving Robinson R22 Beta, VH-HCX, 4 km south-west of Geraldton Airport, Western Australia, on 20 February 2021