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Nacelle yaws automatically during vessel approach

  • What happened?

    A service operation vessel (SOV) was given permission to approach a wind turbine generator (WTG).

    Three technicians had transferred by gangway to the WTG.

    An operator observed that the WTG nacelle was moving (changing direction). The operator immediately contacted the vessel.

    The vessel was moved away from the WTG and the turbine manufacturer’s office was informed.

    Turbine movement could have resulted in the vessel or gangway being hit by the turbine blade.

    Service operation vessel (SOV) with walk to work gangway connected to turbine
  • Why did it happen?

    Remote operator did not place the WTG in ‘stop mode’ before vessel approach.

    This resulted in the WTG automatically starting yawing (due to twisted cables).

    Putting the WTG in stop mode and communicating this to the vessel was not prioritised as first action in the authorised working procedure.

    Why did it happen - icon
  • What did they learn?

    Responsible person should place the WTG in ‘stop mode’ and confirm with the vessel before vessel approach.

    Review procedures and include putting the WTG into ‘stop mode’ as the first step in the operation.

    Implement the ‘four eyes’ principle (two-man rule), where two responsible persons action and check the activity (e.g. place turbine in ‘stop mode’ and confirm that with the responsible person on the vessel).

    Share the incident with the turbine manufacturer so they consider introducing additional engineering controls.

    What learn - icon
  • Ask yourself or your crew

    How could something like this happen here?

    What should you do if something similar happens during today’s transfer?

    What factors can lead to nacelles yawing automatically?

    What measures do we have in place for ensuring turbines are stopped before vessel approach? How can we improve?

    Ask your crew - icon
Published on 18/01/21 1029 Views 0 likes

Three technicians had transferred by gangway from a service operation vessel (SOV) to a wind turbine generator (WTG), when an operator observed that the nacelle was moving. Turbine movement could have resulted in the vessel or gangway being hit by the turbine blade.