Loss of control

What happened

On the morning of 29 April 2012, the owner-pilot of a Cessna 150 aircraft, registered VH-UWR was aerial stock mustering on a cattle station about 55 km north-east of Bourke, New South Wales. Some early patches of fog cleared such that the weather conditions were fine and calm.

After about 1.5 hours in the air, the pilot radioed stockmen on the ground to direct them to an area where cattle were not moving. The aircraft was observed circling over the area then in a steep descent followed by the sound of an impact. The aircraft was seriously damaged, and the pilot sustained fatal injuries.

What the ATSB found

While manoeuvring at low level the pilot inadvertently allowed the aircraft to aerodynamically stall, resulting in a high rate of descent and collision with terrain. There was insufficient information about pilot control inputs to establish the factors that precipitated the stall.

The pilot did not hold a valid medical certificate and had not completed a flight review for a number of years, increasing the risks of operating an aircraft, especially during aerial stock mustering.

Safety message

Pilot proficiency can decline without regular practice of non-routine procedures under the supervision of instructors or approved training/check pilots. As such, pilots should take every opportunity to refresh their knowledge and skills, at a minimum during a flight review every two years.

Preliminary report released 9 March 2012

This preliminary report details factual information established in the investigation’s early evidence collection phase and has been prepared to provide timely information to the industry and public. Preliminary reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003.

At about 1555 Eastern Daylight-saving Time on 4 February 2012, a Robinson R44 Raven II helicopter, registered VH-COK, lifted off from Jaspers Brush Aerodrome, New South Wales for an aerial filming task at Jervis Bay. On board were the pilot and a camera operator.

Soon after lifting off, the pilot's door opened. The helicopter abruptly pitched nose-up and the tailskid struck the ground. The helicopter then abruptly pitched forward and rolled to the right before the main rotor blades struck the ground. A fuel-fed fire started in the vicinity of the fuel tanks and lower mast area. The fuselage then hit the ground. Both occupants were fatally injured, and the helicopter was destroyed.

On 20 December 2010, the manufacturer issued R44 Service Bulletin 78 (SB 78) requiring that R44 helicopters with all-aluminium fuel tanks be retrofitted with bladder-type fuel tanks as soon as practical, but no later than 31 December 2014. At the time of the accident, about 90% of the helicopters originally fitted with all-aluminium fuel tanks, including VH-COK, had not been retrofitted. On 21 February 2012, the manufacturer issued SB 78A that revised the date of compliance to 31 December 2013.

In addition, the manufacturer released SB 82 in respect of the replacement of existing R44 rotor brake switches. The aim of that bulletin was to reduce the chance of the rotor brake switch as a possible ignition source in the event of a fuel leak.

Although the circumstances of this accident are still under investigation, the Australian Transport Safety Bureau has, in the interest of transport safety, issued a Safety Advisory Notice suggesting that operators and owners of R44 helicopters fitted with all-aluminium fuel tanks actively consider replacing those tanks with bladder-type fuel tanks, as detailed in SB 78A as soon as possible. The existence and content of SB 82 is also highlighted.

On 23 December 2011, a Robinson Helicopter Company R22 Beta, registered VH-LNC departed Caloundra aerodrome on a Trial Instructional Flight (TIF).  On board the helicopter were an instructor and student.

Whilst attempting to hover the helicopter the student made a significant and unexpected control input.  Before the instructor could take control, the left skid contacted the ground, and the helicopter rolled over and sustained serious damage.  The instructor and student were uninjured.

Robinson Helicopter Company has identified inexperienced individuals manipulating the controls and dynamic rollover as a significant factor in helicopter accidents.  In response to this accident the helicopter operator has introduced a new policy in regard to TIFs and students manipulating the flight controls below 500 ft above ground level.

Preliminary report released 11 July 2011

At about 1140 Eastern Standard Time on 8 September 2011, a Eurocopter AS350BA helicopter, registered VH-RDU, with a pilot and two passengers on board, collided with terrain on approach to land at a helicopter landing site that was located on a peak of Double Mountain South, Queensland.

The pilot and front seat passenger were fatally injured, and the rear seat passenger received serious injuries. The helicopter was substantially damaged. There was no fire.

What happened

At 1157 on 19 July 2011, a PZL-Mielec M18A Turbine Dromader aircraft, registered VH-FOZ, impacted terrain on a cotton station about 23 km west-south-west of Dirranbandi, Queensland while conducting a spraying flight. The pilot was fatally injured, and the aircraft was destroyed by impact forces.

What the ATSB found

The ATSB found that, for reasons that could not be determined with certainty, the aircraft departed from controlled flight during a turn at low altitude and the pilot was unable to recover before impacting the ground.

The ATSB also identified a significant safety issue affecting the safety of future spraying operations in turbine Dromader aircraft: the potential for the aircraft's centre of gravity to vary significantly depending on the weight in the aircraft's chemical/spray tank and exceed the forward and aft limits during a flight. This safety issue was unlikely to have contributed to the accident as the aircraft was probably within the approved weight and balance limits at the time of the accident.

Moreover, although also not found to have contributed to the accident, there was an increased risk to the flight from the aircraft's operation, at times, in excess of its published airspeed and angle of bank limitations.

What has been done as a result

During the investigation, the Australian Transport Safety Bureau worked with the Civil Aviation Safety Authority (CASA) and the Aerial Agricultural Association of Australia to address the risk to turbine Dromader aircraft of the potential for excessive movement of the aircraft's centre of gravity as the contents of the aircraft's chemical/spray tank are dumped or dispensed.

CASA and the owner/developer of the approval for operations at weights of up to 6,600 kg, which had effect during the flight, took action to improve operator and pilot understanding of the issue. In addition, the owner/developer indicated that the design would be reviewed to address any excessive centre of gravity variations.

Safety message

Although it was not contributory in this instance, the ATSB highlights the importance of pilots maintaining their aircraft's weight and balance within limits throughout a flight, and of understanding the implications of changing weight and balance. Similarly, the ATSB reaffirms the importance of being familiar with and adhering to aircraft operational limitations.

On 18 August 2011, an Aérospatiale Industries AS355F2 helicopter, registered VH-NTV, was operating in an area east of Lake Eyre, South Australia (SA). On board were the pilot and two passengers. The helicopter landed on an island in the Cooper Creek inlet, about 145 km north of Marree, SA, at about 1715 Central Standard Time.

At about 1900, the helicopter departed the island, and soon after take-off it collided with terrain. The pilot and the two passengers were fatally injured, and the helicopter was destroyed by the impact forces and a fuel-fed fire.

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Updated 19 July 2013

The Australian Transport Safety Bureau (ATSB) received the results of the flight simulations and modelling that were previously advised as being conducted by external specialists in June 2012. The ATSB is now finalising its draft report, which will be sent to directly involved parties and other parties with an interest in July/August 2013. Feedback from those parties on the factual accuracy of the draft report over the 28-day DIP period will be considered for inclusion in the final report, which is anticipated to be released to the public in September/October 2013. 

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Updated 9 July 2013

The Australian Transport Safety Bureau (ATSB) received the results of simulations and modelling conducted by external specialists in June 2012. The ATSB is now finalising its draft report, which will be sent to directly involved parties and other parties with an interest in July/August 2013. The final report will be publicly released in September/October 2013.

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Update 26 November 2012

The Global Positioning System (GPS) data that was recovered from the accident site indicates that the helicopter took off normally, before being established on a heading of 035 °M at 1,500 ft above mean sea level (AMSL). After maintaining 1,500 ft for 17 seconds, the helicopter commenced a gradual turn to the right and started to descend. The descending right turn continued for about 35 seconds until the last GPS plot at an altitude of about 728 ft, or about 725 ft above the elevation of the accident site. The location of the accident site was consistent with a continuation of the recorded flight path.

The Australian Transport Safety Bureau (ATSB) is examining various scenarios to explain the helicopter’s flight path, including spatial disorientation and pilot incapacitation. As part of these activities, the ATSB has arranged for simulations to be conducted of the flight by external agencies. Given the time required to conduct and analyse these simulations, the final report is now not expected to be released until the first quarter of 2013.

Although the reasons for the flight path have not yet been determined, the ATSB is concerned about the conduct of visual flight rules (VFR) flights in dark night conditions – that is, conditions with minimal celestial illumination, terrestrial lighting cues or visible horizon. The ATSB is reviewing the regulatory requirements and guidance for the conduct of night VFR flights, and the training and ongoing assessment of pilot skills to conduct such flights. The ATSB is also preparing an ‘Avoidable Accidents’ educational report focussing on night VFR accidents. 

The information contained in this web update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB’s understanding of the occurrence as outlined in the web update. As such, no analysis or findings are included in this update.

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Update 15 August 2012

Since the Preliminary Report was issued on 16 September 2011, the ATSB investigation has:

• examined the helicopter's maintenance and airworthiness records
• examined the helicopter's engines, instruments and other recovered components
• tested fuel samples from the drums that were used to refuel the helicopter
• recovered and analysed data from a GPS device on board the helicopter
• reviewed the pilot's experience and medical status
• analysed witness statements and conducted further witness interviews as required. 

The download and analysis of the GPS data required an extensive period of time, as well as input from overseas investigation agencies.
 
Overall, the analysis of the circumstances of the accident has been difficult due to the limited evidence available.
 
The ATSB has completed its data collection activities and is preparing its draft final report, which will be issued to Directly Involved Parties for their comments.

On 30 April 2011, the owner-pilot of a Robinson Helicopter Co. R44 helicopter, registered VH-ETT, was conducting a local flight from a private property located near Kilmore Gap, Victoria. During low-level manoeuvring at low speed around a dam, the pilot lost directional control and landed heavily in the water. The helicopter was seriously damaged; the pilot and passenger sustained minor injuries.

The investigation found that the helicopter was probably serviceable, and that the loss of directional control was likely to be a result of a loss of tail rotor effectiveness.

The emergency locator transmitter (ELT) activated on impact and prompted an effective search and rescue (SAR) response through a broadcast on the 121.5 MHz frequency. However, the 406 MHz transmission that was monitored by the SAR agency did not trigger an alert or provide identification information. As a result, there was no assurance of an immediate and effective response from the SAR agency.

The investigation found that the ELT could be programmed with identification information either directly or (if fitted) by input from a component (dongle) in the ELT wiring connector. In this occurrence, the ELT had been inadvertently reprogrammed with incorrect information from the dongle.

A minor safety issue was identified in that there were only subtle cues to distinguish programmable dongles from the standard-type wiring connector. There was also variability in the conduct of post-installation ELT testing.

In response, on 6 June 2011, the Civil Aviation Safety Authority (CASA) published Airworthiness Bulletin 25-018 to alert maintenance organisations to the risk of programming dongles transferring potentially invalid details to the memory of ELTs. CASA advised that an article in Flight Safety Australia would also highlight the issue.

The helicopter manufacturer advised that they were introducing measures to increase awareness of programming dongles in their new helicopters.

What happened

On 28 July 2011, at around 1615 Central Standard Time, a Robinson R44 Raven II helicopter, registered VH-ZWC, departed Darwin Airport on a charter flight to Bamurru Plains, Northern Territory. Approximately 30 minutes into the flight, the aircraft lost main rotor drive and the pilot conducted an autorotative descent and landing. There were no reported injuries.

What the ATSB found

The ATSB’s investigation found that the loss of main rotor drive was associated with corrosion and subsequent fatigue failure of the main rotor gearbox gear carrier, as a result of water present in the main rotor gearbox.

What has been done as a result

The helicopter manufacturer has modified the design of the gear carrier to incorporate a metallic cadmium surface plating to improve the corrosion resistance of the assembly.

In May 2012, the Civil Aviation Safety Authority (CASA) released Airworthiness Bulletin 63-008, to raise awareness among operators and maintenance providers of Robinson R44 helicopters of the hazards associated with gearbox internal corrosion due to water ingress. The bulletin made several recommendations aimed at reducing the associated risks.

Safety message

Operators and maintainers of Robinson R44 helicopters are alerted to the potential for the ingress of water into the main rotor gearbox, and for the subsequent corrosion and possible fatigue cracking of componentry, which could lead to a loss of main rotor drive while in flight. Responsible persons are referred to the recommendations contained within CASA AWB 63-008, which are aimed at limiting the likelihood of water ingress and provide guidance on remedial action should water ingress be suspected.

On 3 June 2011, a Kawasaki Heavy Industries 369HS helicopter, registered VH-XAA, collided with terrain 42 km west-south-west of Canberra Airport, New South Wales. The helicopter sustained serious damage and both occupants received injuries.

Earlier that day the helicopter had departed from a private helicopter landing site about 22 km north-west of Canberra Airport for defence aircrew currency training in the Brindabella Ranges, New South Wales. Pre-departure checks had been normal, and the weather was clear.

After identifying a suitable landing site in the Ranges, the pilot reported that he brought the helicopter into a high hover of about 50 -70 ft above ground level (AGL). He assessed that an adequate power margin existed prior to commencing a right tail rotor pedal turn through about 180° to position for landing. Approaching the required position, the pilot applied left tail rotor pedal to stop the turn, however, the helicopter continued to turn to the right. The pilot assessed that he had lost tail rotor effectiveness and commenced recovery actions, but this was hampered by the proximity of nearby trees. The helicopter continued the right yaw through a number of 360º turns while slowly descending. At about 30 ft AGL, the pilot assessed that collision with the trees was imminent and decided to conduct an emergency landing in the clearing below. The helicopter descended rapidly towards terrain and landed heavily in a level attitude, striking a large log. After rapidly rolling through trees then down a bank the helicopter came to rest in a creek bed.

Both occupants exited the helicopter and activated the portable emergency locator beacon. They were later airlifted out by a rescue helicopter.

On 16 January 2011, at about 1800 Eastern Standard Time, a De Havilland Aircraft DH-82A (Tiger Moth) aircraft, registered VH-WHW (WHW), departed Toowoomba, Queensland on a private local flight.

On board was the pilot in command (PIC) and a flying instructor from the local Aero Club. The PIC conducted a pre-flight inspection, which included a check of the fuel, oil and control cables. He determined that WHW was serviceable and had sufficient fuel for the flight. There were no loose items in the aircraft's storage locker or in the cockpit.

About 15 minutes after take-off, the flying instructor, who was acting as the handling pilot at the time, initiated a left turn to return to the airport. The PIC recalled that, during the turn, WHW suddenly pitched down followed by a second, even more severe, pitch down motion. Both the PIC and the handling pilot recalled that the control stick did not move when WHW pitched down.

In response to the sudden and uncommanded nose down motion, both pilots attempted to raise the nose by applying back pressure on the control stick. Their actions had no effect and WHW continued to pitch nose down until the aircraft became inverted.

The aircraft was about 100 ft above the trees and inverted when it began to climb. Both pilots felt significant g-force followed by the collision with the trees.

The aircraft came to rest upside down on the side of Mount Davidson in bushland. Both occupants sustained serious injuries.