A faulty pitch kit has been identified as the cause of the turbine collapse at the Eemmeerdijk wind farm in the Netherlands.

Vattenfall’s statement on the turbine collapse revealed that the incident was caused by a disconnected pitch cylinder, resulting in the loss of blade control and an increase in wind-induced stress.

Despite the application of mechanical brakes, the rotor failed to stop, leading to power output levels exceeding design limits.

Eventually, one blade detached, causing severe imbalance and the subsequent collapse of the upper part of the turbine.

The Swedish wind farm operator said: “One of the lessons we learned from this incident is that a single error should not have such major consequences.

“Although the turbine met all safety requirements 25 years ago, insights have changed in recent years. In the Dutch market, turbines must be thoroughly checked at the end of their type certificate to get a lifetime extension. In the Netherlands, this is after 20 years.

“These checks should include whether the design of a turbine still meets today’s safety requirements.”