content_type: Insights & updates

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

When a turbine blade fails, insurers face uncertainty: Who is responsible, is it an isolated incident, and what is the risk of it happening again? Early information is often limited, conflicting, or biased, leaving insurers without a clear, objective basis for decision-making.

At the same time, there is pressure to act quickly. Claims need to be resolved, liability determined, and repair decisions made, often before the full technical picture is understood. When conclusions are based on incomplete or biased information, the risk of misallocation, repeated failures, and increased long-term costs is high.

Independent wind turbine blade Root Cause Analysis (RCA) helps address this challenge by bringing structure and clarity to complex technical failures. Bladena’s RCA service for wind turbines goes beyond visible damage to uncover why a blade failed, rather than just describing the outcome.

Wind turbine blade failures are rarely driven by a single factor. Design characteristics, manufacturing conditions, transport stresses and operational loading often interact over time in ways that are not immediately visible. Blade failure analysis must therefore consider these factors together. Surface damage alone does not explain the underlying cause.

RCA reconstructs the sequence of events leading to failure using advanced blade assessment tools, specialist structural modelling and simulation. This enables a clear distinction between failure origins and symptoms, giving insurers confidence in blade failure insurance claim decisions.

Rather than stopping at symptoms, Bladena focuses on what drives risk. By understanding how a blade behaves in operation, we clarify cause, responsibility, and whether a failure is an isolated event or a wider fleet risk. 

With RCA and specialist structural analysis, insurers can: 

• establish a clear, unbiased understanding of what happened 
• assess liability based on objective technical evidence 
• validate whether proposed repairs address the true underlying cause 
• evaluate the risk of recurrence across similar assets 
• support claims decisions with transparent, defensible documentation

This is particularly important in multi-party claims, where differing perspectives and financial interests can complicate resolution.

Beyond claims handling, root cause insight also supports better decisions across the insurance lifecycle. Understanding failure patterns and structural sensitivities improves blade structural failure analysis, risk assessment and underwriting. Blade design flaw analysis and wind turbine blade damage assessment help ensure corrective actions reduce the likelihood of future losses.

Where conventional approaches often focus on visible damage and standard repair, Bladena’s RCA focuses on how blades actually respond to operational loads, ensuring the true failure origin is identified rather than only explaining the visible outcome.

As part of RES, this expertise is strengthened by real-world operational experience across a global portfolio, combining structural insight with practical understanding of turbine behaviour in the field. For insurers, this results in clearer decisions, stronger negotiation positions and reduced exposure to repeat losses.

Independent blade structural failure analysis ultimately turns complex blade failures into structured, evidence-based insight, enabling confident liability allocation, effective repair strategies and improved long-term risk management.

Turn uncertainty into clarity.

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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.