Category: Blog

By Andrei Buliga, Digital Blades Project Director at RES, supporting Bladena

When a wind turbine blade fails, insurers need more than a description of the visible damage. They need to understand what happened, why it happened, who may be responsible, and whether the same issue could affect other assets.

That clarity is not always easy to reach. Early information can be limited, conflicting or shaped by the interests of different parties. And where uncertainty remains, insurers can face greater exposure to dispute, misattribution, repeat failures and long-term cost.

Bladena provides independent root cause analysis for wind turbine blade failures, helping insurers make evidence-based claims decisions with greater confidence.

Speak to our balde failure experts

When the cause is unclear, claims decisions become harder

Blade failure claims can quickly become complex.
Multiple stakeholders may be involved, each with their own interpretation of the incident. When there is no clear, independent technical evidence to rely on, it can be difficult to separate fact from assumption, or to determine whether a proposed repair addresses the real cause of failure.

For insurers, this creates uncertainty around some of the most important questions in the claim:

• What was the actual failure mechanism?
• What factors contributed to the failure?
• Is the failure isolated, or could similar assets be exposed?
• Are proposed repairs technically appropriate?
• Is there enough evidence to support a clear liability position?
• Could the same issue happen again

Visible damage does not always explain the true failure

Conventional approaches often focus on where a blade has failed, what repair may be required and what can be seen on the surface. But visible damage is often the outcome of a deeper issue, not the explanation in itself.

Wind turbine blade failures are rarely driven by a single factor. Their behaviour can be shaped by design characteristics, manufacturing conditions, transport stresses and operational loading. In many cases, the true cause of failure only becomes clear when these factors are assessed together.
That’s why root cause analysis is so important.

Bladena’s RCA process is designed to reconstruct the sequence of events leading to failure. By combining specialist blade structural assessment, operational evidence, modelling and simulation, Bladena helps distinguish between the visible symptoms of damage and the true origin of failure.

[Comparison table]

Conventional approaches may focus on…	Independent RCA helps reveal…
What damage is visible	Why the failure occurred
What repair may be required	Whether the repair addresses the underlying cause
The individual incident	Whether there may be wider fleet-level exposure
Differing stakeholder interpretations	Evidence-based understanding of causation
The visible blade condition	A defensible basis for claim evaluation

Evidence-led insight for clearer claims decisions

Bladena’s independent root cause analysis gives insurers a more robust technical basis for claim evaluation, liability discussions and future risk assessment.

With RCA and specialist structural analysis, insurers can:

• Establish a clear, unbiased understanding of what happened
• Assess liability using objective technical evidence
• Distinguish between failure symptoms and failure origins
• Validate whether proposed repairs address the true underlying cause
• Evaluate the risk of recurrence across similar assets
• Support negotiations with transparent, defensible documentation
• Make more informed decisions across claims, underwriting and risk evaluation

This can be particularly valuable in multi-party claims, where differing perspectives and commercial interests can make resolution more difficult.

Independent RCA in action: disputed blade failure claim

Bladena combines specialist structural insight with practical understanding of turbine behaviour in the field. As part of RES Group, Bladena’s insight is strengthened by real-world operational experience across a global renewable energy portfolio.

If you’re working through a disputed claim, liability question or blade failure scenario, Bladena can provide independent technical insight to support claim evaluation, liability discussions and repair decisions.

Background

Following a blade break incident, an insurer faced a disputed claim involving multiple stakeholders and differing interpretations of the technical cause.

The insurer needed an independent assessment to clarify the failure mechanism, understand whether the event was isolated or indicative of wider fleet risk, and establish a defensible position for claim resolution.

The challenge

Different parties had presented different views of causation, leaving the insurer without the clarity needed to assess liability or move the claim forward. Bladena was brought in to provide an independent investigation that could go beyond surface-level damage interpretation and determine the underlying failure mechanism.

Bladena’s role

Bladena carried out an independent root cause analysis, delivered without commercial ties to any of the parties involved.
The investigation combined specialist blade structural assessment with operational evidence to determine the true cause of failure.

The analysis included:
• failure mechanism identification
• load-damage correlation
• design envelope assessment
• manufacturing indicator review
• evidence-based hypothesis elimination

This approach allowed Bladena to test different explanations, rule out unsupported assumptions and build a clear technical causation narrative.

The impact

The RCA gave the insurer a clear, unbiased and technically substantiated basis for claim evaluation, liability discussions and stakeholder alignment.

The findings supported:
• a clearer causation narrative
• improved liability clarity
• reduced uncertainty in claims decisions
• faster claim resolution
• reduced dispute complexity
• a stronger negotiation position
• better visibility of potential fleet-level risk

For the insurer, the value was not only in understanding a single failure. It was in gaining the evidence needed to make a confident decision under scrutiny.

Want to find out more?

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By Mathias Reding, Director of Engineering, Bladena

Blade reliability remains a critical focus, with recent failures not only increasing the levelised cost of energy but also risk reputational damage and create safety concerns, affecting relationships with communities and investors.

Across RES, we have catalogued over 1 million instances of damage across 100,000 blades to date, giving us deep insight into long-term performance and failure patterns, particularly for blades with five or more years in operation where statistical trends become more robust. We also have early-stage insights from design reviews, testing data and failure cases across more than 130 blade models, including the latest multi-megawatt platforms, adding further depth to our understanding.

Blade failures are rarely caused by a single factor; more often, they reflect a complex interplay of design, manufacturing, transport and operational stresses . While manufacturing and quality assurance are actively improving, aligning design more closely with operational data could be the key to further reducing failures – helping the industry scale power output in a cost efficient way that minimises risk.

Blade length and stress do not scale evenly

Recent analysis completed by Bladena shows a potential correlation between the likelihood of blade failure within the first five years of operation and blade length. Leading to the conclusion that a key contributing factor in more frequent blade failure could be down to how blade designs are being scaled for larger turbines. Longer blades – which are common today – incur more stress proportional to shorter blades. As most longer blade designs are simply scaled up versions of shorter blades, this additional stress has not been properly factored into the design.

Standards and testing do not fully reflect real-life conditions

Design flaws like these should, in theory, be caught during testing. But there’s a disconnect between what blades are tested for and the conditions that they face in real-life operations, and the gap is widening as larger turbines come to the market.

Designers work to meet the test criteria required for certification, but for longer blades, the criteria is not being revised often enough to reflect the higher stress and fatigue that those blades will experience in operation. As a result, we continue to see issues, which implies that blade design continues to outpace certification criteria. One example we noted from our own analysis is the limited requirements for assessing torsional load.

The current design basis only considers the loads associated with displacements in the edgewise and flapwise direction independently and not the combined three-dimensional effect which is found under actual turbine operating conditions. As a result, a blade can pass certification but still fail within months in the field.

In the race to launch more powerful turbines to accelerate the energy transition, engineers are often designing the next model before field data from the previous version is available to inform design improvements. Without resetting the design methodology, old assumptions persist, even though the data shows new blades behave differently.

Pioneering new testing for real-world conditions

To better understand how blades respond under real operational stresses, Bladena, in collaboration with the Offshore Renewable Energy (ORE) Catapult, is launching full-scale testing of next-generation blade reinforcement technology. Using an 88-metre blade at ORE Catapult’s National Renewable Energy Centre, this programme will carry out torsional load tests for the first time at this scale. The results will help refine blade designs, improve operational longevity, and guide future industry standards, bringing testing closer to the real-world conditions blades experience at sea.

Solving the issue with detailed root cause analysis data

As innovation accelerates to meet net zero ambitions, it is paramount that we align design and testing to real-life scenarios and close the feedback loop for good. Conveniently, the data already exists to do this. By analysing failure data across 130+ blade models, from early designs to today’s multi-megawatt platforms, we’re uncovering the patterns and risks that allow for better decisions across the full blade lifecycle.

The potential impact is vast – billions of dollars in remanufacturing, AEP losses and reputational damage could be abated through a more rigorous approach to applying data insights.

What’s failing most?

Based on our analysis, the five most critical failure modes we see include:

1. Trailing edge cracking and bondline failure
2. Transverse cracks in the max chord area
3. Shear web bondline failure
4. Cracks & irregularities in transition zones
5. LPS (Lightning Protection System) related damages

We’ll explore each of these in more detail in a dedicated blog series, sharing what to look for and how to respond before it leads to failure.

If you’re already facing persistent blade issues, now is the time to act.

A robust root cause analysis, grounded in real-world failure data, can uncover hidden drivers and support targeted interventions that reduce risk before it escalates.

We have the data to fix this, so together, let’s make blade failure a thing of the past.

As part of the CORTIR III project supported by the EUDP (Energy Technology Development and Demonstration Program), we have performed a field measurement campaign on the 7MW ORE Catapult Levenmouth Demonstration Turbine in Scotland, featuring 83.5-meter blades.

Understanding the hidden risks in wind Turbine Blades

At first glance, a crack in a wind turbine blade might seem like an isolated incident—a single point of failure. But in reality, it’s often just the final symptom of a much deeper issue. Structural fatigue and weaknesses due to design decisions can silently accumulate over time, gradually pushing a blade closer to its breaking point.

That’s why we believe there is value in going beyond surface-level inspections to understand what’s really happening inside a blade—and how that insight can help prevent costly failures in the future.

Why blade failures can occur

Blades are subjected to immense forces throughout their operational life. Each gust of wind, each change in temperature, each start-up and shutdown cycle contributes to structural wear and tear. While modern blades are built to endure these stresses, even small compromises—whether in design, materials, or manufacturing—can add up.

Over time, this can lead to what’s known as cumulative fatigue: damage that builds gradually until it reaches a critical point. By the time a crack appears, the underlying issues may have been developing unnoticed for years.

Why design decisions matter

Many of the risks associated with blade failure can be traced back to the design phase. Blades are designed to meet industry standards, but real-world conditions can vary considerably, meaning they may not be fully accounted for during the design. Decisions may have been made in order to reduce weight or lower material costs, leaving certain areas under-reinforced when considering the variable real-world scenarios. These weak points might not be visible externally, but they can become the origin of structural degradation over time—especially in blades exposed to high turbulence or complex loading conditions.

Understanding these vulnerabilities is essential not only for preventing failure but for optimising performance across the entire fleet.

Why visual inspections aren’t enough

Routine inspections play an important role in blade maintenance and combining both internal and external inspections increases the opportunity to identify damage and catch issues before they develop further. But, they have their limits. Visual inspections often only detect damage once it’s well advanced. Cracks, delaminations, or fibre failures may already be compromising the blade’s integrity by the time they’re spotted.

This is where data-driven structural insight becomes invaluable. Using advanced modelling and simulation, we can detect early indicators of stress and fatigue, assess the specific risk factors present in each blade design, and identify where intervention could make the biggest difference.

Data-driven decisions with Bladena
At Bladena, we offer a unique combination of engineering expertise, tools, and services to help you take control of blade risk before it leads to failure. Our methodologies are grounded in physics-based modelling and decades of industry knowledge. We help you:

• Pinpoint structural weaknesses in specific blade types
• Model the effects of cumulative fatigue under real-world conditions
• Evaluate the impact of reinforcement or retrofitting
• Optimise inspection schedules based on risk rather than routine

By understanding the “why” behind failures—not just the “what”—we give asset owners, OEM´s and operators a clearer path forward.

Looking ahead: proactive risk management

The cost of a single blade failure can be significant—not just in terms of repair or replacement, but also downtime, lost production, and long-term fleet reliability. That’s why a proactive approach, grounded in structural insight, is essential.

If you’re ready to understand where your risks lie – and what you can do about them – our experts are here to help.