In the wind energy industry, wind turbine manufacturers and operators face the potential for litigation related to wind blade defects and maintenance. Design, manufacturing, installation, and maintenance issues may lead to legal challenges. Addressing these concerns is fundamental to avoiding litigation and ensuring the longevity and efficiency of wind turbines.
Common Issues Leading to Litigation – In the wind energy industry, wind turbine manufacturers and operators may sometimes face litigations related to wind blade quality. Such litigations may arise due to issues related to the wind blades’ design, manufacturing, installation, or maintenance (this repeats four items just cited above). Common problems that may lead to litigation related to wind blade quality include:
A CICNDT technician conducts surface inspection of a wind turbine blade using advanced testing equipment, ensuring quality and defect detection
1. Design Defects: The wind blade may have design defects that could lead to premature failures, such as inadequate material strength (insufficient margin to cover fabric waves, dry spots, or partial bond contact area) or improper lighting system design.
2. Manufacturing Defects: The inadequate control of the manufacturing process may have caused defects such as delamination, cracks, or voids in the composite material used for the blades. Additionally, issues could exist with the metallic root attachment or the joints between major structural components, such as the webs and spar caps.
3. Installation Defects: The team may not have carried out the installation process correctly.., leading to local damage on the blades, misalignment, or other issues that could lead to premature failure.
4. Maintenance Issues: Poor maintenance practices, such as inadequate inspection or repair, may lead to premature wear or damage to the blades.
5. Transportation Indications: The most common types of transportation damage to wind blades are cracks, chips, and scratches on the surface of the blades or fracturing of the blade shell joints, which can affect their performance and durability
Inspection Technology – Innovative inspection technologies are crucial in addressing these concerns. Ultrasonic Testing (UT) inspection technology is reliable for identifying manufacturing errors and pinpointing early signs of damage and degradation. Leveraging UT can proactively address potential issues, prevent unnecessary waste, safeguard warranty integrity, and avoid significant disruptions or shutdowns. UT is ideal for detecting and characterizing flaws in wind energy assets, including lightning damage, delaminations, heat damage, impact damage, disbonds, erosion, and cracking. It is important to remember that this is not the only inspection technique to address all variables that need to be measured. Build a list of essential recordable data to ensure the appropriate inspection methods, techniques, and equipment are selected.
1. A-scan: Provides amplitude and time-based signals to represent internal structures visually.
2. B-scan: Produces cross-sectional images showing structural details’ size, shape, and position.
3. Amplitude C-scan: Utilizes amplitude to create images of surface or sub-surface components.
4. Time of Flight C-scan: Generates information about internal structures’ thickness, shape, and location.
5. 3D model: Offers real-time interpretation and visual features representing the object’s physical attributes.
A transducer module paired with tablet software showcasing multi-dimensional defect data, including A-scan, B-scan, amplitude C-scan, and 3D visualization for structural analysis.
Design Defects—Design defects can occur in wind blades when the engineering and design process fails to account for all the potential stresses and loads the blades will encounter during their lifespan. These defects can lead to premature blade failure, reduced energy production, and increased maintenance costs.
1. Poor material selection: The choice of materials for wind blades is critical to their performance and durability. Using low-quality or incompatible materials can result in premature wear and tear, cracking, and delamination.
2. Inadequate reinforcement: Wind blades are subject to high stresses and loads, especially at the root and transition to maximum chord. Insufficient reinforcement in these areas can lead to structural failure and reduced blade life.
3. Flawed aerodynamics: Wind blade design must consider the complex aerodynamics of wind flow and its impact on blade performance. Flawed designs result in lower energy production and increased noise levels.
4. Manufacturing defects: Errors during the manufacturing process, such as improper curing or bonding, especially bond voids, can result in structural defects that compromise blade performance.
Wind blade designers and manufacturers use advanced computer modeling, simulation tools, and extensive testing to validate the design and identify potential issues, preventing design defects before installing the blades on the wind turbine.
In addition, regular maintenance and inspection of wind blades can help detect any signs of damage or defects, allowing for prompt repair or replacement before they lead to more serious issues.
Results from a Sandia National Laboratories trial: technical drawing and ToF (Depth) C-scan showcasing reflectors, flat-bottomed holes, and disbonds in a GFRP wind blade sample.
Manufacturing Defects – Manufacturing defects can occur in wind blades during production, significantly impacting the blades’ performance and reliability. Common manufacturing defects in wind blades include:
1. Improper curing: Wind blades are typically made from composite materials, which require careful curing to ensure their strength and durability. Improper curing can lead to weak spots, delamination, and other defects, compromising the blade’s structural integrity.
2. Bonding failures: Manufacturers often bond multiple layers of materials together to create strong, lightweight wind blades. Bonding failures, such as voids or weak spots, can cause delamination and other structural defects.
3. Contamination: During manufacturing, contaminants such as dust or oil can weaken the blade’s structure and lead to premature failure.
4. Dimensional errors: Small dimensional errors during manufacturing can add up over the blade’s length and result in significant performance issues, such as increased noise levels or reduced energy production.
Wind blade manufacturers use advanced quality control processes to prevent defects and ensure that every blade meets strict quality standards. These processes include extensive testing and inspection, such as non-destructive testing, to identify any defects that may be present. Manufacturers also use automated methods to minimize the risk of human error and ensure consistent quality.
Wrinkles in a 20mm GFRP wind blade skin are analyzed using ToF and amplitude thresholds, enabling early defect detection and prompt repairs to prevent serious issues.
Installation Defects – Installation defects can occur when wind blades are not installed properly on the wind turbine. These defects can compromise the performance and reliability of the blades and the entire wind turbine. Common installation defects of wind blades include:
1. Misalignment: Wind blades must be installed in a specific orientation to ensure proper aerodynamics and maximum energy production. Misalignment can lead to increased drag, reduced energy production, and increased wear and tear on the blades and the turbine.
2. Inadequate tightening: Manufacturers typically secure wind blades to the hub with bolts tightened to a specific pre-load. If they fail to tighten the bolts adequately, it can result in loose or damaged bolts, compromising the structural integrity of the blade and the turbine.
3. Improper blade balance: Wind blades must be balanced to rotate smoothly and efficiently. Improper balance can lead to increased wear and tear on the blade and the turbine, increased noise levels, and reduced energy production.
4. Damaged components: Wind blades rely on various components, such as sensors, controllers, and pitch systems, to operate effectively. Damage to these components during installation can compromise the blade and turbine’s performance and reliability.
Wind turbine installers follow detailed installation procedures and use specialized tools and equipment to ensure they install the blades correctly and prevent defects. They also perform extensive testing and inspection to ensure the blades are aligned correctly, properly tightened, and well-balanced.
After installing the blades, technicians perform regular maintenance and inspections to detect signs of installation defects, such as loose bolts or damaged components, and promptly repair or replace them before more serious issues develop.
Inspection in Service – Preventing Defects
Dimensional results of a 38mm thick wind blade section, identifying thickness regions (A-E) and backwall echo loss using advanced inspection techniques.
Maintenance Issues – Maintenance issues of wind blades can arise due to various factors, such as environmental conditions, wear and tear, and manufacturing defects. Rapidly addressing these maintenance issues is crucial to ensure optimal performance and maximize the lifespan of the blades. Common maintenance issues of wind blades include:
1. Surface erosion: Environmental factors such as rain, snow, wind, and sand expose wind blades to surface erosion. This erosion reduces aerodynamic efficiency, generates noise, and decreases energy production.
2. Leading edge erosion: Wind blades’ leading edges are particularly vulnerable to erosion, which can cause pitting, cracks, and other damage. Leading edge erosion reduces the blade’s aerodynamic efficiency and increases its noise level.
3. Lightning strikes: Lightning strikes can damage the surface, electrical systems, and structural integrity of wind blades leading to premature wear and tear, reduced energy production, and increased maintenance costs.
4. Fatigue: Throughout their lifespan, the blades are subject to repeated stresses and loads, which can cause fatigue and result in cracks, delamination, or other structural damage.
5. Manufacturing defects: Missed indications due to manufacturing.
Regular Blade Inspection & Preventative Maintenance is Critical
Regular inspection and maintenance of the blades are essential to address these maintenance issues.
Wind blade inspections using UT for defect detection, shown with handheld devices, rope access technicians, and automated crawlers for thorough assessments.
Owners/operators should regularly perform regular maintenance activities such as surface cleaning, repairing leading-edge erosion, and replacing damaged components as per the manufacturer’s guidelines. Technicians use non-destructive testing techniques to inspect and identify internal structural defects such as delamination or cracking.
Even Getting the Blades Deployed Comes with a Risk
Transportation Damage—The shipping process can cause defects in wind blades, as companies often transport the blades over long distances, sometimes across international borders.
Visual representation of delamination detected in a wind blade hub end, highlighting structural integrity issues using inspection data mapping.
These defects can compromise the structural integrity of the blades and increase the risk of premature failure. Common transportation defects in wind blades include:
1. Impact damage: Wind blades can sustain impact damage during shipping due to mishandling or contact with other objects. Figure 7 below shows an inspector evaluating the root section after being impacted by a forklift during unloading operations. Impact damage can result in cracks, chips, or other types of damage, such as trailing edge bond splitting, compromising the blade’s structural integrity.
2. Vibration damage: Vibrations during transportation can cause internal structural damage to the blade, such as delamination or cracking.
3. Environmental damage: Extreme temperatures, humidity, or exposure to saltwater can damage the blade surface and weaken its structural integrity.
4. Moisture damage: Moisture can seep into the blade during shipping, which can cause swelling, warping, and other types of damage. (note: The composite blade is primarily immune to this, but the metallic root and lightning system components are not, so that may be a better focus for this point)
Upon arriving at their destination, the blades undergo a checklist inspection to ensure they are free from defects and damage. Technicians repair or replace detected defects or damage as necessary before installing the blades on the wind turbine.
CEO Jeremy Heinks uses UT equipment to inspect the wind turbine blade root section, ensuring structural integrity and defect-free performance.
Conclusion
To avoid litigations, wind energy industry participants can take measures to prevent issues that can lead to claims. Manufacturers can ensure that their blades meet industry standards and regulations and that their quality control procedures are up to par. Installers ensure proper blade installation by following the manufacturer’s guidelines. Operators can perform regular maintenance and inspections to prevent issues and ensure their wind turbines operate safely and efficiently.
In the event of a legal claim, parties involved may seek the help of legal experts to navigate the legal process and represent their interests. Factual inspection evidence from an NDT instrument, such as UT, may provide pivotal evidence.
If you are interested in learning more about the inspection of wind blades or have additional questions about the litigations above, don’t hesitate to contact us. We welcome further discussion and are here to assist you with any inquiries. Please explore our services because your engagement is valued, and we look forward to providing more detailed insights on these critical matters or connecting you with those who can help!
Reference List
- Sandia National Laboratories
Research and case studies on wind turbine blade performance, design defects, and inspection methodologies.
(https://www.sandia.gov) - National Renewable Energy Laboratory (NREL)
Reports on wind energy advancements, maintenance practices, and design optimization for wind turbines.
(https://www.nrel.gov) - American Society for Nondestructive Testing (ASNT)
Guidelines and standards for non-destructive testing techniques relevant to wind turbine blade inspections.
(https://www.asnt.org) - International Electrotechnical Commission (IEC)
Standards for wind turbine design, testing, and certification, including IEC 61400.
(https://www.iec.ch) - Global Wind Energy Council (GWEC)
Insights on wind energy trends, challenges, and best practices to ensure blade quality.
(https://gwec.net) - WindProve LLC
Expertise in wind turbine blade inspection, damage evaluation, and quality assurance practices.
(https://windprove.com) - CIC NDT, LLC
Specialists in advanced non-destructive testing for wind turbine components and composite materials.
(https://www.cicndt.com) - Composite Materials Research Group
Publications on the use of composite materials in wind energy, with a focus on structural integrity and defect prevention.
(https://www.compositesworld.com) - Blade Root Cause Analysis Reports
Studies on common wind blade failures, including design, manufacturing, and maintenance-related issues.
(Available through various industry white papers and publications.) - Turbine OEM Technical Manuals
Manufacturer-specific guidelines for the proper installation, maintenance, and inspection of wind turbine blades.
(Accessible through turbine manufacturers like GE, Siemens, or Vestas.)