IMCA recently released its Safety Flashes for September, summarizing an incident where a yawing of wind turbine nacelle placed ship in line of fire.
The case
A wind turbine started yawing, placing an approaching vessel in the line of fire. A turbine nacelle had been confirmed as locked on requested heading and permission had been given for the vessel to enter the turbine safety zone.
The vessel entered the safety zone, connected, transferred technicians to the turbine via walk-to-work gangway, then completed cargo transfer to the transition piece (TP) using the ship’s crane.
The vessel then moved off from the TP and was about to start moving astern (in the direction of current flow) when it was noted that the nacelle heading was about 50 degrees different to that requested, with a turbine blade directly in the vessel’s intended path.
The move was cancelled and the ship moved ahead, away from the blade disk, on DP joystick auto-heading. The safety zone was exited without further event.
Findings
The new, oncoming crew on the turbine tower yawed the nacelle using local controls, assuming that the vessel had moved clear, not considering time taken to complete cargo operations. There was no communication with the bridge or client crew before starting the move.
What were the causes?
- Lack of situational awareness;
- Failure to follow established communication protocols.
Lessons learned
- Operator’s procedures were reviewed and teams reminded of the requirement to receive positive confirmation that vessels are clear before moving the nacelle;
- As engineering-based Lockout/Tag-out controls are not practicable, procedural/administrative controls were made more robust;
- Operator’s communication protocols were strengthened and communicated;
- Reminder stickers ‘WAIT FOR GREEN LIGHT BEFORE YAWING’ were placed on all control boxes.
