High potential dropped objects from wind turbine Nacelle crane

What happened?

Two lifting bags detached and fell from the crane hook on a wind turbine tower. The incident occurred during lowering operations at the end of an annual service day in the wind turbine nacelle. A contractor technician packed up tools and equipment and loaded them into certified lifting bags. The bags were then loaded onto the nacelle crane hook for lowering to the transition piece. During the operation, two of the lifting bags became detached from the crane hook and fell approximately 60 meters into the sea. Both of the bags were recovered from the sea; there were no injuries or property damage.

This is an historical event from 2016 which has been recently shared with IMCA for incident learning and sharing purposes.

What went wrong?

• The safety latch on the lifting hook had suffered damage and failed. The investigation noted that this potentially indicated that the hook was incorrectly loaded, which had resulted in excess pressure on the safety latch of the crane hook causing it to become defective.

What actions were taken?

• Ensure any planned lifting operations are verified to ensure safe loading techniques are employed;
• A toolbox talk (TBT) to be delivered to all service technicians as a reminder of the correct procedure for rigging the nacelle crane and dangers of incorrect loading.

Members may wish to refer to:

• High potential near-miss: Failure of lifeboat release hook mechanism
• Near-miss: Non-fatal man overboard incident [latch failure]