Aviation safety investigations & reports

Loss of cyclic control and in-flight break-up involving Robinson R22 helicopter, VH-HGU, 7 km north-north-west of Cloncurry Airport, Queensland, on 2 August 2017

Investigation number:
AO-2017-078
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final Report

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What happened

On the morning of 2 August 2017, the pilot of a Robinson R22 Beta II helicopter, registered VH‑HGU and operated by Cloncurry Mustering Company, departed Cloncurry Airport, Queensland, on a ferry flight in preparation for an aerial mustering operation. About 3 minutes after take-off, the pilot experienced a loss of control and the helicopter broke-up in-flight. The helicopter collided with terrain about 7 km north-north-west of Cloncurry. The pilot, who was the only occupant, was fatally injured and the helicopter was destroyed.

What the ATSB found

The ATSB found that the helicopter had recently undergone a 2,200-hour overhaul and this was the first commercial flight since that time.

The on-site examination established that the bellcrank in the helicopter cyclic control assembly was missing a fastener, which allowed the assembly to disconnect in-flight. The ATSB concluded that it was likely that the fastener’s self-locking nut was either not reinstalled or it was inadequately torqued during the overhaul. While it could not be determined what had occurred to result in this condition, it was noted that Cloncurry Air Maintenance (CAM) did not use the work-pack to record and track all maintenance activities during the overhaul, which extended over a period of almost 4 months.

The ATSB noted that, in the years leading up to the accident, the CAM workforce structure had changed in a manner that reduced the levels of its qualifications and experience. In the month leading up to the accident, the CAM workforce was operating at a very high workload, which likely exceeded their workforce capability and reduced the chief engineer's capacity to oversight maintenance activities.

Cloncurry Air Maintenance (CAM) had limited internal independent oversight of maintenance activities to evaluate its quality performance. The organisation was subject to both contracted and regulator audit activities in the years leading up to the accident. The ATSB reviewed two of the work-packs sampled during the audits and noted that discrepancies in their maintenance documentation practices were visible to the auditors. However, the auditors had not identified any issues associated with those practices, and therefore, the audits were of limited benefit to CAM.

It was also established that CAM were re-using the MS21042L-series nuts on critical fasteners without replacing them with D210-series corrosion resistant nuts in accordance with the manufacturer's instructions. However, the ATSB also found that the re-use of self-locking nuts was a common and accepted industry practice.

What's been done as a result

Cloncurry Air Maintenance have improved their maintenance practices, which has included progressive certification for tasks, adopting the helicopter manufacturer’s checklists for their inspections, removing all untracked MS-series self-locking nuts from stores, and completing inspections of the flight controls on all the Cloncurry Mustering Company helicopters with nil defects reported.

In March 2019, the Australian Transport Safety Bureau issued a safety advisory notice advising all Australian maintenance personnel for Robinson helicopters to ensure that before re-using a self‑locking nut, that the correct part number is fitted, and that the D210-series corrosion-resistant nuts are used for reassembly of critical fasteners in accordance with the Robinson Helicopter Company instructions for continued airworthiness.

As a result of this accident and other investigations by the Civil Aviation Safety Authority, the regulator issued airworthiness bulletin 67-005: Robinson Helicopter Flight Controls – Independent Inspections. The bulletin highlighted the need for independent inspections to be conducted and ‘recorded consecutively with each adjustment made during rotor tracking and balancing’ activities. In addition to several recommendations, the bulletin identified several human factor elements that could impact maintenance inspection performance, and highlighted the need for extra caution to be exercised during post-maintenance flights as per the guidance provided by Robinson.

Safety message

Although verbal communications are an important method of explaining and understanding problems, they are not a reliable means for capturing essential tasks over an extended time‑period. This accident highlights the importance for maintenance organisations to consider the human factors elements associated with their practices, capture them in their documented quality control procedures, and ensure they are complied with.

Audits are essential for independently verifying the effectiveness of an organisation's processes and procedures. This accident reinforces the importance of auditors inspecting the evidence collected during an audit to ascertain whether or not the requirements are being met, specifically conformance with the relevant standards. Audits may also be used to identify potential underlying human factors issues, which may be raised as an opportunity for improvement to inform the auditee of best industry practices.

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The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

Appendices

Safety Issue

Go to AO-2017-078-SI-01 -

Maintenance practices

Cloncurry Air Maintenance had adopted a number of practices, which included using abbreviated inspection checklists, not recording all flight control disturbances and not progressively certifying for every inspection item as the work was completed, which increased the risk of memory-related errors and the omission of tasks.

Safety issue details
Issue number: AO-2017-078-SI-01
Who it affects: Cloncurry Air Maintenance
Status: Closed – Adequately addressed
General details
Date: 02 August 2017   Investigation status: Completed  
Time: 0702 EST   Investigation level: Systemic - click for an explanation of investigation levels  
Location   (show map): 7 km north-west of Cloncurry   Investigation phase: Final report: Dissemination  
State: Queensland   Occurrence type: Flight control systems  
Release date: 21 July 2020   Occurrence category: Accident  
Report status: Final   Highest injury level: Fatal  

Aircraft details

Aircraft details
Aircraft manufacturer Robinson Helicopter Co  
Aircraft model R22 Beta  
Aircraft registration VH-HGU  
Serial number 4335  
Operator Cloncurry Mustering Company  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Destroyed  
Departure point Cloncurry Airport, Queensland  
Destination Cloncurry Airport, Queensland  
Last update 21 July 2020