Unintended yawing during software update

What happened?

Several tests were carried out on the Offshore wind turbine generator (WTG).

Each time a reboot occurred, the stop command was cleared, causing the WTG to revert to active yaw.

The same tests were repeated on two other locations.

In both of these tests, the WTG held the command and did not return to active yaw.

This issue was due to a bug in earlier releases of a piece of software.

It was this version that was the operating software of the WTG in the near miss event.

All relevant locations have since been updated to the latest software revision, mitigating the risk of this incident happening again.

Ensure all locations are up to date with the latest software.

Implement additional control as redundancy together with current stop procedure.

Do you know the backup plan if this occurs? What is it?

Are new software versions available? When was this last checked?

Has the current software version been properly tested?

What happened?

Several tests were carried out on the Offshore wind turbine generator (WTG).
Each time a reboot occurred, the stop command was cleared, causing the WTG to revert to active yaw.
The same tests were repeated on two other locations.
In both of these tests, the WTG held the command and did not return to active yaw.
Why did it happen?

This issue was due to a bug in earlier releases of a piece of software.
It was this version that was the operating software of the WTG in the near miss event.
All relevant locations have since been updated to the latest software revision, mitigating the risk of this incident happening again.
What did they learn?

Ensure all locations are up to date with the latest software.
Implement additional control as redundancy together with current stop procedure.
Ask yourself or your crew

Do you know the backup plan if this occurs? What is it?
Are new software versions available? When was this last checked?
Has the current software version been properly tested?