Winch cable fouling, Leonardo AW139, 19 km south-east of Warrnambool, Victoria, on 15 December 2020

What happened

On 15 December 2020, at about 1900 Eastern Daylight-saving Time,[1] the crew of a Leonardo AW139 helicopter were conducting the winch retrieval of three people stranded on a cliff near Childers Cove, Victoria. The crew comprised the pilot, aircrew officer and a paramedic.

The paramedic was winched to the ground and recovered the first stranded person. The aircrew officer then manoeuvred the paramedic and the first person into the aircraft cabin. To allow them to move into the aircraft seats, the aircrew officer winched out some cable to provide slack in the cable. During this winch-out procedure, the slack cable was dispensed onto the aircraft floor and out the cabin door. The aircrew officer was aware that the cable was outside the cabin, but not the length of cable that was outside the cabin, and the looped section was not visible. When the aircrew officer commenced the winch-in of the hook assembly, the cable failed (Figure 1).

The aircrew officer secured the loose end of the winch cable and the pilot landed the helicopter in a nearby carpark to assess the situation. It was found that the cable had looped around the right undercarriage shock absorber trunnion resulting in the failure of the winch cable and damage to several undercarriage components.

Figure 1: Reconstruction of cable fouling and severed winch cable hook assembly

Source: Operator

The helicopter was inspected on site shortly before last light by one of the operator’s engineers and was cleared to return to base. However, it was later determined that the damage to the undercarriage rendered the helicopter unserviceable.

Safety action

As a result of this occurrence, the operator has advised the ATSB that they have taken the following safety actions:

• A Safety Alert has been promulgated throughout the company to reinforce the importance of cable control during all phases of winching operations.
• All personnel have been reminded of the general safety philosophy of the company, which demands that safety related activities, including aircraft inspections and checks, are not rushed nor influenced by time pressures. Any activity should be stopped immediately if any person has any doubt about the safety in relation to a particular operation they are involved in.
• A learning package is being developed to facilitate sharing of the incident details and findings within the company and other helicopter emergency medical service operators.

About this report

Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.

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[1]     Eastern Daylight-savings Time (ESuT): Coordinated Universal Time (UTC) + 11 hours.