Rotor and blades fall from turbine at Rugby wind farm, North Dakota

On 14 March 2011, the rotor and three large blades detached from one turbine tower at the Rugby wind farm, near Rugby, North Dakota, and fell to the ground. The site, operated by Iberdrola Renewables Inc., has 71 turbines and a capacity of up to 149 megawatts. No one was injured. Iberdrola described the failure as a rotor assembly failure in a letter to North Dakota's Public Service Commission. The wind farm was inspected following the incident and judged safe, resuming operation about a week later, on 21 March 2011. An investigation into the cause had not been completed at the time the farm resumed generating. The turbine manufacturer, Suzlon Wind Energy Corp., called the event an isolated incident and stated confidence in the safe operation of its global turbine fleet.

Iberdrola stated the cause was a rotor assembly failure, though the full investigation had not concluded by the time reporting occurred.

1. Rotor and blade assembly failures can occur without warning and should be included in routine structural inspection regimes.
2. Operators should promptly inspect and assess remaining fleet turbines of the same design following a similar failure before resuming full operations.
3. Transparent regulatory reporting, such as notifying a state public service commission, supports timely investigation and public confidence following mechanical failures.

deseret.com/2011/3/21/20180399/rugby-wind-farm-resumes-operation-aft...