About 3,800 wind turbine blades fail per year, according to an insurer.[1] About 0.5% per year. A detailed analysis of blade failure modes: [2] There's an industry devoted to blade repair.[3] What they do looks a lot like body work for carbon-fiber aircraft, except that it's done in midair.

Transmissions and bearings are more of a problem. "Turbine gearboxes are typically given a design life of 20 years, but few make it past the 10-year mark."[4]

[1] https://www.enr.com/articles/42352-are-four-wind-turbine-fai... [2] https://backend.orbit.dtu.dk/ws/portalfiles/portal/118222161... [3] http://fairwindres.com/wind-industry-maintenance/blade-repai... [4] https://www.windpowerengineering.com/wind-turbine-gearboxes-...

It is all about trying to avoid having a broken/breaking wind turbine. A spinning wind turbine falling apart is no fun for bystanders involved [0].

[0]: https://www.youtube.com/watch?v=7nSB1SdVHqQ