Overgrown helipad contributes to tail rotor strike and collision with terrain.

While manoeuvring close to the ground in a confined and overgrown landing site on Moa Island in the Torres Strait, the pilot of a LongRanger helicopter experienced difficulty locating the helipad before the helicopter’s tail rotor contacted trees, resulting in the helicopter spinning rapidly and colliding with terrain.

On the morning of 22 April 2020, the Bell 206L1 LongRanger operated by Nautilus Aviation was conducting a passenger charter flight from Moa Island’s Kubin Airport to Banks Peak with a pilot and two passengers on board.

Shortly after 8.00am, the pilot manoeuvred over the top of the helipad and used the helicopter’s rotor downwash to push away overgrown grass to reveal the edges of the helipad. During this process, the tail rotor contacted several tree branches of up to 45 mm in thickness located on the eastern side of the helipad.

A video taken by one of the passengers recorded that as the helicopter was turning to the right, a buzzing sound was heard followed by a crack. Immediately after this sound, the helicopter spun rapidly to the right before rolling left and colliding with terrain.

The video also showed that during the accident sequence, the left rear door opened. As a result of the spinning and rolling, the rear left passenger’s legs were forced out of the door and became trapped under the helicopter, resulting in serious injuries. The right rear passenger sustained a serious injury to one hand.

During the accident, the pilot’s helmet impacted the aircraft’s structure, resulting in a brief loss of consciousness. Paint transfer on the pilot’s helmet was of a colour matching the interior paint of the cabin. The investigation found that the use of a helmet very likely reduced the severity of the pilot’s injuries.

“The wearing of helmets is an important safety consideration when performing utility aerial work,” Director Transport Safety Dr Mike Walker said.

“Survivability in the event of an accident, as was highlighted in this case, is greatly increased by wearing a helmet.”

The investigation also highlights the importance of the design and ongoing maintenance of helicopter landing sites and helipads in tropical environments, and that maintenance schedules must account for rapid plant growth.

“Helicopter landing site owners are encouraged to add touchdown and positioning markings to their facilities,” Dr Walker said.

“Additionally, if a landing cannot be conducted as planned, pilots should reject the landing and go-around to re-evaluate their options from a safe position away from obstacles.”

Safety action taken by Nautilus Aviation since this accident has seen its HLS template amended to include a grading system for site assessment by the chief pilot or deputy chief pilot prior to tasking pilots. Nautilus has also developed a risk assessment template for landing at non-surveyed sites, in addition to sending an alert to its pilots reinforcing the go-around procedure as stated in its operations manual.

The lessee of the helicopter landing site, the Department of Home Affairs, has also conducted a formal risk assessment of Banks Peak and other higher-risk sites throughout the Torres Strait. The Department has ceased flying operations to landing sites deemed to have unacceptable risks until sufficient control measures have been implemented. In addition, the Department is developing a detailed HLS brief for aircraft operators and is considering the most appropriate mechanisms for systematic engagement with other users of its landing sites.

Read the final report: Collision with terrain involving a Bell 206L-1, VH-NBR, at Banks Peak, Moa Island, Queensland, on 22 April 2020

Train replacement coach driver surprised level crossing was activated for freight services in the area. 

Key points

• Coach stopped foul of tracks on level crossing after crossing protection warnings began operating.
• Coach stopped despite having adequate time to clear the crossing.
• The train was unable to stop and impacted the front-left corner of the coach

A passenger coach was struck by a freight train after it stopped foul of a Geelong level crossing when the coach driver stopped on the crossing after boom gate warning lights activated, despite having adequate time to clear the crossing, a new transport safety investigation notes.

The coach, with a driver and single passenger on-board, was operating a rail-replacement service from Melbourne to Waurn Ponds in Geelong on the morning of 2 April 2020 and had just entered the Station Street level crossing when the crossing warning system activated in response to an approaching freight train. The driver of the coach immediately applied the brakes and the coach stopped within the crossing, foul of the first track.

When the crew of the freight train observed the coach, the locomotive driver made an emergency brake application while the co-driver began to sound the horn. The coach driver heard the train horn and attempted, unsuccessfully, to reverse the coach off the crossing.

The train was unable to stop and impacted the front-left corner of the coach. The coach driver and passenger were injured in the collision and were taken to hospital. The coach driver was released from hospital the same day, and the passenger the next day.

The subsequent investigation into the incident, conducted on behalf of the ATSB by Victoria’s Chief Investigator Transport Safety, confirmed that the coach had stopped past the boom barrier with the front-left corner of the coach foul of the track.

The acute road-to-rail track angle and the position of the left-front corner of the bus relative to the track may have influenced the driver’s perception of the crossing, the investigation notes.

“Had the driver not stopped the coach when the crossing warning system activated, there was adequate time to complete the crossing prior to the arrival of the freight train,” said Chief Investigator Chris McKeown.

At interview with transport safety investigators, the driver indicated that he did not continue over the crossing as he did not want to be reported for crossing with the bells ringing.

Further, the driver indicated that he was surprised when the crossing was activated, as they were under the impression that V/Line trains were not running because they were driving a train replacement service.

When the coach driver was alerted to the train’s presence by the train horn, the driver recalled attempting to reverse the coach, but reported that they had forgotten to release the park brake.

“Motorists need to be aware that in situations where passenger train services are not operating, freight trains may be operating, and normal safety precautions should be observed,” stated Mr McKeown.

Although probably not directly related to this incident, in the previous six years, there had been 20 occurrences of the boom barrier strikes by road vehicles on the inside lane of the Station Street approach. This suggests that the crossing configuration is probably conducive to driver error on that approach, and that additional risk controls may be warranted, Mr McKeown noted.

“While there were no identified queueing issues at the crossing that may have triggered a requirement to applying yellow box markings, such markings may have assisted the driver’s identification of the crossing limits and the hazardous zone.”

Read the final report: Level crossing collision between freight train 5KQ7 and a road coach, at Norlane, Victoria, on 2 April 2020

An update on the investigation into the collision with terrain at Carcoar, NSW.

The ATSB will analyse data from the pilots’ personal electronic devices and evaluate witness information as part of its on-going investigation into the fatal accident of an Aquila training aircraft south of Orange, Central West New South Wales, on 4 November 2020.

An instructor and a student pilot undergoing a check flight prior to undertaking a commercial pilot licence flight test were on-board the aircraft when it collided with the ground shortly after departing a private airstrip at the Coombing Park property, near Carcoar, south of Orange.

The investigation update notes that the aircraft impacted the bank of a small dam, located on rising terrain about 600 metres beyond the end of the runway and about 30° to the left of the runway centreline.

“To date, the ATSB has examined the aircraft wreckage, interviewed witnesses, and retrieved personal electronic devices and aircraft components from the accident site,” said ATSB Acting Director Transport Safety Kerri Hughes.

“On-site examination of the aircraft’s flight controls, engine and structure did not identify any pre‑existing faults or failures,” she said.

“In addition, evidence of fuel spillage at the accident site indicated that the aircraft had fuel onboard, while the presence of fuel in the fuel filters indicated the engine had fuel supply at the time of the accident.” 

The investigation update also notes that the recorded weather at nearby Orange Airport at the time of the accident included visibility of greater than 10 km with no cloud detected, and an 11 knot wind from the west.

Ms Hughes noted the progress update does not include any safety findings or analysis, which will be detailed in the investigation’s final report.

“As well as analysis of electronic data from the pilot’s personal electronic devices and considering witness information, the ATSB will also examine a number of recovered aircraft components and analyse the aircraft’s maintenance history, weight and balance, and performance,” she said.

“The ATSB will also examine flight planning for the accident flight; the operator’s policies and procedures; and review pilot qualifications, experience and medical information.”

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,” Ms Hughes noted.

Read the investigation progress update.

Repaired engine component contributes to engine failure and forced landing incident.

The Australian Transport Safety Bureau welcomes US Federal Aviation Administration (FAA) consideration of the adoption of an Airworthiness Directive that seeks to address the likelihood of compressor turbine blade failures in certain variants of the PT6A turbine engine fitted with repaired compressor turbine vane rings.

In August 2020 the FAA released a notice of proposed rulemaking of its consideration to issue the Airworthiness Directive (AD) which would require operators to check for, and remove specific third party‑repaired compressor turbine vane rings from Pratt & Whitney Canada PT6A‑114 and PT6A-34 series engines, which power single-engine Cessna 208B Caravan and aerial application aircraft, respectively.

The AD was first issued by Transport Canada and subsequently adopted by Australia’s Civil Aviation Safety Authority in 2019, and came in conjunction with an ATSB investigation into an engine-failure incident involving a Caravan aircraft with two pilots and 11 passengers onboard which force landed on a service road near the Solomon mine site in Western Australia on 16 November 2016.

In that incident the Caravan aircraft had departed Solomon Airport bound for Karratha when at an altitude of 4,600 feet the engine failed, with the pilots hearing a loud bang and observing smoke billowing from the exhaust.

On commencing a right turn back towards the airport, the pilots assessed that a return there would not be possible due to uncertainty over whether over they could safely avoid high terrain.

Scanning the immediate area, the pilots identified an unsealed dirt road as their planned emergency landing area. The subsequent landing was accomplished without injury to the occupants and the aircraft was undamaged apart from flat spots on the main gear tyres due to emergency braking on landing.

“A compressor turbine blade from the engine developed fatigue cracking and fractured after approximately 1.8 hours of operation, leading to the engine failure and resulting in the forced landing of the aircraft,” said ATSB Director Transport Safety Stuart Macleod.

“The compressor blade fracture in turn could be attributed to variations in the aerofoil geometry of a repaired compressor turbine vane ring. The variations likely led to increased vibratory stresses within the compressor turbine blade, and the development of fatigue cracking during operation of the engine.”

The investigation identified that the use of FAA-approved repaired compressor turbine vane rings significantly increased the likelihood of single-crystal 

compressor turbine blade fracture in PT6A-114A engines, compared to engines fitted with Pratt & Whitney Canada‑manufactured compressor turbine vane rings.

“This involved and complex investigation has resulted in significant safety actions being taken by a number of parties,” Mr Macleod said.

The compressor vane repairer, Southwest Turbine Inc, ceased conducting repairs on CT vane rings for fitment into PWC PT6A-114A engines in March 2017.

Also, in March 2017, the engine manufacturer, Pratt & Whitney Canada, released a Service Instruction Letter advising of the heightened risk of CMSX-6 single-crystal compressor turbine blade fatigue fracture when combined with a compressor turbine vane ring that had been repaired using processes that were not approved by PWC.

Then in August 2019, Transport Canada (the regulatory certifying authority for the PT6A engine) released airworthiness directive CF-2019-30, which required operators to check for, and remove, Southwest Turbine‑repaired CT vane rings from PT6A‑114 and PT6A-34 engines within a period of 9 calendar months, or 250 hours of operation.

That AD was immediately adopted by the Civil Aviation Safety Authority, requiring Australian operators to also remove Southwest Turbine-repaired compressor turbine vanes rings fitted to the PT6A-114A and PT6A‑34.

“Due to the significant safety action taken by the directly involved parties since the occurrence, including action from the engine and component manufacturers, as well as the aviation regulatory authorities, the ATSB considers that the risk of CMSX-6 single-crystal compressor turbine blade fractures in Australian‑operated PWC PT6A-114A engines has been adequately addressed,” Mr Macleod said.

“Further, the ATSB welcomes the initiation of safety action by the FAA to consider legislation of the Transport Canada AD. However, with closure of the NPRM on 1 October 2020, the ATSB notes that at the time of publication, no decision has been made whether the AD will be adopted.”

Mr Macleod said the occurrence shows how subtle changes can have unintended detrimental effects.

“In this instance, geometry variations in a repaired compressor turbine vane ring likely led to rapid fatigue cracking and fracture of a compressor turbine blade, and subsequent engine failure.”

Separately, the incident also reinforces the importance of communication and effective decision-making during an emergency, Mr Macleod said.

“The pilots’ response to the engine failure and subsequent emergency landing was handled in a competent and proficient manner that reduced the risk of damage to the aircraft and injury to passengers or crew,” he said.

“Noting the rugged terrain surrounding Solomon Airport, the decision to land on the access road considerably reduced the risk of damage and injury.”

Read the report: Engine failure and forced landing involving Cessna 208B, VH-LNH, 8 km north-west of Solomon Airport, Western Australia, on 16 November 2016

Overcharged light rail vehicle battery.

Key points:

• Battery overcharging generated excessive hydrogen that ignited and ruptured the battery system enclosure
• Software controlling the battery charging voltage was ineffective due to undetected data corruption
• Numerous ‘battery over temperature faults’ were recorded in the train monitoring system but drivers were not alerted

A light rail vehicle’s roof-top mounted battery system ruptured and ejected the enclosure cover off the vehicle’s roof when excessive hydrogen generated from battery overcharging ignited, a new ATSB report says.

The Sydney Light Rail vehicles (LRV) 053/054 were stabled at the light rail depot in Randwick overnight on 2–3 April 2020. At about 2:49 am workers in the yard heard a loud noise and found a roof-mounted battery enclosure cover on the ground behind two other light rail vehicles.

A review of closed-circuit TV footage showed a flash coming from the battery enclosure as the cover was ejected from the roof of LRV 053. The cover struck the overhead contact wire and was airborne for about 5 seconds before striking the two nearby LRVs and falling between them.

“Undetected data corruption of the battery system’s auxiliary converter configuration software, likely present from its initial upload and throughout validation testing, resulted in the batteries overcharging and high battery cell temperatures going undetected,” said Mick Quinn, Acting Chief Investigator, Office of Transport Safety Investigations (OTSI).

In New South Wales, OTSI conducts rail and light rail investigations on behalf of the ATSB under the Transport Safety Investigation Act 2003

“The auxiliary converter configuration software changes the battery charger voltage in response to battery cell temperature; as the battery cell temperature increases the charger voltage should decrease,” Mr Quinn said.

Overcharging then depleted the electrolyte levels of the battery cells and generated excessive hydrogen within the batteries.

“As flammable gases, including the hydrogen, released into the battery enclosure and encountered an undetermined ignition source they ignited and the force of expanding gases ruptured the enclosure ejecting the cover from the roof of the vehicle.”

“The ejected cover weighed 20 kg and was airborne for approximately 4.12 seconds in which time it struck the overhead contact wire likely slowing the ascent,” Mr Quinn explained.

“The cover landed approximately 6 m away from LRV 053 and posed a significant hazard to anyone in the area. Further, chemical hazards could also have caused burns or eye damage if released when the enclosure ruptured.”

The investigation notes that while a ‘battery over temperature fault’ was recorded in the train monitoring system when battery temperatures reached 60 °C for more than 5 seconds, and the fault warning was retained for review in the maintenance list in the driver’s display unit, no alert was generated for the driver.  

A review of the maintenance list found the battery had recorded frequent over temperature faults in the 30 days leading up to the occurrence.  

“The introduction and commissioning of new assets like light rail vehicles must ensure that design requirements and risk controls are tested and validated as functional and that fault monitoring and maintenance regimes monitor asset condition to avoid circumstances that might escalate and contribute to accidents,” said Mr Quinn.

As a result of the occurrence, the train monitoring system was updated so that it alerts light rail drivers to battery over temperature faults, while additional software validation and testing is planned by the battery charger software supplier and vehicle manufacturer during software acceptance testing and after the upload of revised software.

Read the final report: Uncontained battery failure involving Sydney Light Rail Vehicle 053, Randwick LRV Depot, New South Wales, on 3 April 2020

Safety Advisory Notice warns of cracking in Yak-52 aluminium elevator bellcranks.

The ATSB has released a Safety Advisory Notice to Yakovlev Yak-52 aircraft owners and maintainers highlighting the potential for fatigue cracking in Yak-52 aluminium alloy elevator bellcranks.

The Safety Advisory Notice comes as a result of the ATSB’s ongoing investigation into the collision with water of a Yak-52 aircraft during a private aerobatic flight near South Stradbroke Island, Queensland, on 5 June 2019, in which the pilot and passenger were fatally injured.

“During the course of the investigation, the ATSB detected two small cracks in the aircraft’s aluminium elevator bellcrank, one of which was established to be a pre-existing fatigue crack,” said Acting ATSB Director Transport Safety, Kerri Hughes.

“The ATSB stresses that the crack did not contribute to the South Stradbroke Island accident. However, cracking in this area can result in the failure of the bellcrank and a subsequent loss of control of the aircraft,” said Ms Hughes.

A review of the available Yak-52 maintenance documentation identified a difference in the requirements for inspecting the bellcrank, Ms Hughes noted.

In 2009, Yakovlev amended the aircraft’s scheduled maintenance program to require a dye penetrant inspection of the elevator bellcrank every 25 flying hours (plus or minus 5 hours). In 2012, as a result of a fatal Yak-52 accident in 2010, where the elevator bellcrank had failed in-flight, Yakovlev directed that all aluminium bellcranks be replaced with steel.

However, the Yak-52 is an ex-military ‘warbird’ aircraft that was not designed to western civil certification standards and is flown in Australia under a Limited category special certificate of airworthiness.* Consequently, neither the 2009 requirement to use dye penetrant inspections every 25 flying hours, nor the 2012 requirement to replace aluminium bellcranks with steel bellcranks, had been incorporated into maintenance schedules for the aircraft in Australia, and nor was there a requirement to do so.

In Australia, Yak-52 elevator bellcranks were required to be dye penetrant inspected every 100 flying hours or 12 months.

“Given the known fatigue cracking and potential failure of Yak‑52 elevator bellcranks manufactured from aluminium alloy, the ATSB reminds maintainers and operators of the importance of dye penetrant inspections to detect and remove defective bellcranks from service,” Ms Hughes said.

“The ATSB would also like to ensure that operators and maintainers of Yak‑52 aircraft are aware that Russia, the aircraft’s state of design, increased the inspection frequency for the bellcranks to 25 plus or minus 5 flying hours. Further, aluminium alloy bellcranks are no longer approved for use on Yak-52s operating in Russia.”

The ATSB’s investigation into the South Stradbroke Island accident is continuing, with a final reported anticipated to be released in the first half of 2021. Pending the publication of an investigation’s final report, the ATSB may issue Safety Advisory Notices to raise awareness of safety critical concerns determined during the course of an investigation without waiting for the conclusion of the investigation.

Read the Safety Advisory Notice AO-2019-027-SAN-024: Elevator bellcrank inspections

* Under the Civil Aviation Safety Authority’s Limited category(Opens in a new tab/window), operators can fly warbird ex-military and replica aircraft in Australia on an ‘informed participation’ basis where they are willing to accept the risk of the aircraft not meeting international airworthiness certification standards.

Aviation Occurrence Statistics report update.

The ATSB has released an update to the Aviation Occurrence Statistics report with the inclusion of 2019 aviation activity data (hours flown and aircraft departures) not available at time of initial publication.

ATSB Director Transport Safety, Dr Stuart Godley said the earlier report published in April contained 10 years of occurrence data from 2010 to 2019, but that aviation activity data (used to calculate rates) was only available from 2014–2018.

“The addition of last year’s aviation activity data allows for accident rates to be presented for the period 2014–2019,” said Dr Godley.

“Accident rates (accidents per hour flow or departure) is an important measure for the level of risk associated with different aviation activities and allows for a comparison between activities.”

The updated statistics shows that aviation activity involving test and ferry flights, aircraft registered with Recreational Aviation Australia (RAAus), followed by pleasure and personal transport, had the highest accident rates over 2014–2019.

For aircraft types of aircraft, recreational aeroplanes followed by commercial balloons are shown to have the highest accident rates, with recreational aeroplanes also having the highest fatal accident rate. 

Dr Godley explained that in order to provide more timely information to industry, the Aviation Occurrence Statistics report will now be published bi-annually, with the data published earlier in the year to include occurrence data (number of occurrences) for the previous year followed by an update later in the year including updated activity data.

“Both occurrence data and rate data are important tools for assessing the safety risk of aviation activity by providing two reports the ATSB aims to present safety information in a timely and relevant manner to industry,” he said.

The updated edition also incorporates interactive web versions of all tables and graphs to allow the user to display aviation occurrence data in the format of their choice.

Read the report AR-2020-047: Aviation Occurrence Statistics (rates update) 2010 to 2019

Turbulence during shallow approach results in collision with terrain.

Key points:

• Approach profile was lower than intended.
• Aircraft pitched up on encountering turbulence.
• Accident highlights the importance of aircraft adopting an approach profile that mitigates the effects of gusty or turbulent conditions.

Turbulence during a shallower than intended landing approach resulted in the pilot of a Cessna 172 aircraft electing to reduce power and land in a tree canopy about 50 metres short of the runway threshold, an ATSB report says.

On 22 March 2020, a Cessna 172 aircraft, registered VH-CCB, took-off for a local private flight from a private airfield at Canyonleigh, near Mittagong, in New South Wales, with the pilot and passenger on board. Soon after take-off the aircraft experienced turbulence and the pilot and passenger decided to terminate the flight. The aircraft turned for its final approach about 1 NM from the runway threshold and 400 ft above aerodrome level.  As it approached the runway over steep forested terrain, the pilot reported the approach profile was lower than intended and increased power. The aircraft then pitched-up on encountering turbulence.

After correcting the pitch attitude, the pilot saw the aircraft remained lower than expected and was not aligned with the runway. Uncertain whether the aircraft would be able to climb over the canopy to the runway the pilot reduced power and landed in the tree canopy. The aircraft came to a rest 50 metres short of the threshold and to the left of the runway. The pilot and passenger sustained serious injuries and the aircraft was substantially damaged.

The ATSB’s safety message featured in the report highlights the importance of adopting an approach profile that mitigates the effects of gusty or turbulent conditions. Also, pilots need to be go-around prepared and minded and go around if the approach becomes unstable.

For more information on for go-around preparedness read the Flight Safety Foundation Approach-and-landing Accident Reduction briefing note 6.1(Opens in a new tab/window) from the Approach-and-landing Accident Reduction (ALAR) Tool Kit.

Read the final report: Collision with terrain involving Cessna 172, VH-CBB, 31 km west of Mittagong, New South Wales, on 22 March 2020

ATSB releases APL England loss of containers investigation preliminary report.

An ATSB preliminary investigation report details that a container ship was rolling and pitching heavily in rough seas and high winds when it lost 50 containers overboard about 46 nautical miles south-east of Sydney on 24 May 2020.

The on-going investigation’s preliminary report sets out the incident’s sequence of events and outlines that as the APL England travelled down the east coast of Australia, the Bureau of Meteorology issued regular forecasts regarding a complex low-pressure system developing off the south-east of the country, with gale force wind warnings.

“By 0600 on Sunday 24 May, while maintaining a southerly course and a speed of about 7 knots, the ship was pitching and periodically rolling in high seas and gale force winds,” said ATSB Chief Commissioner Greg Hood.

“Shortly after, at 0610, the ship experienced a series of very heavy rolls, to about 25° either side of upright. On the bridge, with many items moving and falling to the deck and the crew holding on to maintain their footing, steering system and engine room alarms sounded, and then the main engine shut down due to a loss of oil pressure.”

The report details that the crew restarted the engine, by which time the ship had turned to port, beam on to the seas, while continuing to roll heavily. The ship slowly gathered speed, and was turned easterly and then southerly, into the weather, before the crew then decided to head north, with the weather.

“It was not until skies had lightened - sunrise was at 0647 - that the chief officer first noticed the fallen stacks of containers,” Mr Hood noted.

“It was later established that 50 containers had been lost overboard from both forward and aft bays. One container lost overboard contained hazardous goods in the form of dry powder fire extinguishers, while 23 containers were empty.  A further 63 containers were damaged but remained on board.”

The ship would recover to the Port of Brisbane, where ATSB transport safety investigators were able to board the vessel to survey the damaged container stacks, inspect the container lashing equipment, download the vessel data recorder and video recording system, and interview the crew.

“Generally, the ship’s lashing equipment appeared in good condition. However, many of the ship fittings including lashing eyes, lashing bridges and deck structures were found to be heavily corroded and wasted,” Mr Hood said.

In addition, ATSB examination of the container stowage arrangement showed that the use of ‘high cube’ (2.9m/9ft 6in high) as opposed to standard height (2.6m/8ft 6in) containers in the ship’s aft-most container bay, bay 62, affected the security of the stow above the container cell guides.  However, the loading computer’s lashing and forces checks did not show any conflicts for this arrangement.

Mr Hood noted that the preliminary report does not include any safety findings or analysis, which will be detailed in the final report.

“The on-going investigation will review and analyse several areas of interest including the ship’s container stow and lashing arrangement; the maintenance regimes for the ship’s deck and engine room; the ship’s service and inspection history; the ship’s stability condition; weather conditions and information provided to crew; and the actions of the ship’s crew,” 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,” Mr Hood concluded.

Read the preliminary report: Loss of containers overboard from APL England, 46 NM south-east of Sydney, New South Wales, on 24 May 2020

Collision with terrain following in-flight simulated engine failure.

Key points:

• Aircraft rolled to the right and impacted the ground after a simulated engine failure after take-off
• Exercise was conducted in a configuration in which the aircraft was unable to maintain altitude with one engine inoperative
• Pilot likely had skill decay from lack of recent flying, instructor had minimal experience in aircraft type and limited experience in multi-engine aircraft with retractable landing gear

A twin piston-engined Angel 44 utility aircraft was conducting a simulated engine failure, when, about 20 seconds after take-off from Mareeba Airport in far north Queensland, it rolled rapidly to the right and impacted the ground, fatally injuring the pilot and instructor.

An ATSB investigation into the 14 December 2019 accident details that the aircraft was being used for a flight review of the aircraft’s owner-pilot, who was seated in the left seat, with an instructor in the right seat.

Witnesses at Mareeba Airport observed the aircraft touch down on the runway, accelerate and take off again. After take-off, the aircraft climbed to about 100–150 feet above ground level before entering the right descending turn.

“The ATSB found that shortly after take-off, the flight instructor very likely conducted a simulated failure of the right engine on a warm, humid day at a high aerodrome elevation in a configuration in which the aircraft was unable to maintain altitude with one engine inoperative,” said ATSB Director Transport Safety Dr Stuart Godley.

“Power was not immediately restored to the right engine to discontinue the exercise and the pilots were unable to maintain altitude or heading, particularly with the aircraft banked towards the inoperative engine,” Dr Godley said.

“The pilots did not reduce power and land ahead, as required by the aircraft’s flight manual, resulting in a loss of directional control and the aircraft rolling to the right. The loss of control occurred at a height too low to recover and the aircraft impacted terrain in a cornfield 475 metres north of the runway.”

Neither the pilot nor the instructor had any recent experience in the aircraft, which had not been flown regularly for more than two years, the investigation notes.

In addition, the pilot had not flown for three years before the accident, which likely resulted in a decay of skills at managing tasks such as an engine failure after take-off, while the instructor had limited experience in multi-engine aeroplanes with retractable landing gear, and had only once before flown the Angel 44 aircraft, several years earlier.

As a consequence, the investigation notes that the instructor was likely unfamiliar with the time necessary for the landing gear and flaps to retract – approximately 14 seconds, significantly longer than other aircraft the instructor had flown – and the associated detrimental effect that extended flaps and landing gear had on the aircraft’s single-engine climb performance.

“In light twin-engine aeroplanes, loss of power on one engine shortly after take-off poses a high risk due to low height above ground, low airspeed and generally limited single-engine climb performance,” Dr Godley said.

“When conducting simulated engine failures, it is essential that pilots understand the risks and ensure effective controls are in place to prevent the simulation turning into a loss of control at low level, where recovery will probably not be possible.

“Attempting to continue flight with one engine inoperative in a multi-engine aeroplane when directional control cannot be maintained, carries a high risk of an accident and fatal injuries.”

Dr Godley said the ATSB assessed whether the accident occurred following a simulated or real engine failure, as witnesses reported hearing an engine ‘splutter’ sound.

However, no evidence of a complete power loss was found, with both engines producing power at the time of impact, and with the ‘splutter’ consistent with simulation of an engine failure by rapidly retarding the throttle.

Nonetheless, investigators established that two of the fuel injectors in the right engine showed evidence of partial blockage by corrosion particles. That would have resulted in the over-fuelling of the other injectors and the engine running overly rich, backfiring, and reducing the maximum power available.

In the two years the aircraft had not been flown, its engines had not been preserved in accordance with the manufacturer’s procedures, the investigation notes.

“If an aircraft is not flown regularly, the airframe and engine/s need to be preserved in accordance with the manufacturer’s procedures,” Dr Godley noted.

Read the report: Loss of control and collision with terrain involving Angel Aircraft Corporation 44, VH-IAZ, near Mareeba Airport, Queensland, on 14 December 2019