Blade failures are rising, here is where to focus

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Let's talk about the elephant in the room.

When I worked as a technical authority in oil and gas I was used to managing the high potential risks of operating high-speed turbomachinery surrounded by high pressure gas. The risks of operating wind turbines are generally lower. One exception is the risk of blade failures, which have the potential to and tragically have resulted in a fatality (Akita, Japan, May 2025).

When I first started in renewables, blade failures were rare, the sort of thing you heard about as that one historic incident. Unfortunately, that is no longer the case, and blade failures like the one in the photo, taken near Coalburn, South Lanarkshire, Scotland, are becoming more common.

Some of the reasons the rate is increasing:

• More turbines are operating, so the absolute number of failures naturally rises.
• Modern offshore blades are over 100m long and far more slender than the 40m blades of the 2000s, as the scale comparison below shows. What the picture cannot show is the consequence. The longer, thinner blades are much more flexible, which brings tougher aeroelastic and fatigue loading, with durability controlled by the adhesive joints and bond lines where many failures start.
• A large fleet built during the early expansion years is now reaching life extension. Newer failure modes, for example blade root insert bonding failures, are becoming an increasing risk.

Akita was a smaller, older machine, but it shows a second risk that grows as the fleet ages, hidden internal damage that inspection does not catch. The January 2026 investigation found the root cause in the lightning protection design of the blade. On this 2 MW machine with 38.8m blades, the carbon fibre spar caps were not electrically bonded to the lightning protection system, a design that met the IEC standard at the time. That left a path for low-current, steep-front lightning to arc inside the blade, causing internal discharge damage and delamination that grew under fatigue until the blade broke, on a day when the wind was within design limits.

Given the safety and reputational stakes, the industry cannot keep doing the same thing and expect a different result. Where I think the focus should be:

• Share technical safety incidents, not just personal safety incidents. Oil and gas learned this the hard way and now openly shares technical safety learnings. In wind the failure is too often labelled an isolated manufacturing defect, when the real cause is a design or process issue, and NDAs limit shared learning. Tragically it often takes a fatality before these failures are fully investigated and the learnings publicly shared.
• Blade inspections should be targeted, layered and risk based depending on the age, size and known failure modes for that blade model. External inspection caught most issues on older blades, but newer longer blades fail faster and often with limited external sign. The layered approach should still include external inspections, which are increasingly cheap and quick, but should be complemented with internal inspections at key points such as 1 year after commissioning, end of warranty and approaching life extension. After Akita, Japan is moving to require internal inspection of the areas around the down-conductors regardless of access, in practice using drones or crawlers inside the blade. Targeted NDT should then be used where there are known serial defects with that blade model.
• Structural Health Monitoring hardware should be factory fitted to new wind turbines as a critical layer on top of inspections to help detect failures that propagate faster than inspection intervals. Most older 2 MW turbines have full gearbox condition monitoring systems, yet most new 10 MW-plus offshore turbines have no blade SHM installed. Blade load sensors are increasingly common but are designed to manage loads not for blade health monitoring. SHM is the right direction for large flexible blades but not mature enough to rely on alone, so more reliable solutions should be a research priority. This is not a reason to hold off fitting any SHM solution now but a reason to ensure sufficiently comprehensive sensor hardware is installed now to allow future software updates. This approach is similar to the Tesla software update model but with the learning of getting the hardware spec right to start with.
• Make sure the design assumptions hold in practice. Under IEC 61400-1, the parked loss-of-grid case, DLC 6.2, normally requires large yaw misalignment, up to 180 degrees in either direction, to be analysed. That severe case can be avoided only where backup power keeps the yaw and control systems running for at least 6 hours. Where a design relies on that allowance, the backup power must be demonstrably available on site 24/7, including during commissioning, not just for planned grid outages.
• Look again at the blade certification test basis. Certification fatigue tests are still predominantly single-axis, loading flap and edge separately rather than together. In service the two act at the same time, and that combined loading is what fatigues the trailing edge and bond lines, where many failures start. Dual-axis testing is more representative of real loading and is available today, but it is not the standard certification requirement.

Blade failures are a high potential risk that needs wider industry focus. They show why the right monitoring matters, and why inspections must be scoped to the turbine model and its known failure modes at key points such as life extension.

This is where independent, owner side reviews earn their place, scoping life extension inspections around the failure modes that actually matter and flagging those modes and the correct maintenance intervals during technical due diligence.

Reference. January 2026 investigation into the Arayahama Wind Power Station blade failure, by Japan's Ministry of Economy, Trade and Industry and the operator, Sakura Wind Power and Hitachi Power Solutions. English summary at DeepWind. Photograph and graphic by PowerVeritas.