These blades don’t typically break. We have thousands of windmills in Germany and maintenance-wise, they are built to last.
There’s a fairly impressive wind farm in Indiana, with many of the turbines visible close up along I-65 between Lafayette and Indianapolis.
Just one thing, though. In the four or five times I’ve been by there, I’ve never seen them turning. Honest!
They break. Over-speed them, or buffet them with very gusty winds, and they’ll break.
The failure rate isn’t high, but the number of turbines installed recently is large, and utilities and operators will start to develop failure analysis studies and statistics in a few years.
Ice and snow build-up on the blades distorts the airflow over the blades and can result in unplanned stresses on the blades.
We had one turbine in southeastern Wyoming launch a blade. You don’t want to be near where they land...