About this project:
Client:
Deutsche Windtechnik
Windfarm:
Seamer
Address:
Seamer, England
Date:
November 2024
Duration:
270 Hours
Access Method:
Rope Access and Internal Repair
Project Information
Bladestar Renewables Ltd were tasked with repairing a Cat 5 repair to a blade in the Seamer, England. A team of complex repair specialists were deployed to complete the repair. Utilising our own inhouse Limited Authorised technicians we were able to work self-sufficiently throughout the project. This enabled us to handle the repair from start to finish without any external support from the customer. The defect in question, was actually 2 previous repairs that had failed. Previous contractor had not eliminated the defect resulting in the cracks reappearing. Original defect was 4000mm at 0 degrees and 1700mm at 90 degrees. Location on the blade was between 3m and 7m from the root.
Key Points
• Repair time = 270 hours via rope access and internal repair.
• Bladestar inhouse Senvion Limited AT’s.
• All layers from external to internal affected incl. Severe crack in SPAR.
• Previous poor quality repairs by third party resulted in reappeareance of cracks.
• Detailed repair report sent out to customer within 72 hours of completion.
• Bladestar inhouse Senvion Limited AT’s.
• All layers from external to internal affected incl. Severe crack in SPAR.
• Previous poor quality repairs by third party resulted in reappeareance of cracks.
• Detailed repair report sent out to customer within 72 hours of completion.
Investigation
Investigation was started by removing surrounding topcoat to further expose the defect. External Uni-directional and Biaxial layers were found to be cracked. As a result the balsa was also affected and would require replacement. Due to the time of year and to avoid being affected by climatic conditions, majority of the repair would be tackled internally.
Repair
External Repair
Before any repairs could be started, all previous repairs had to be removed to restore blade back to its original profile. Once all previous repairs had been removed, it was discovered that the original crack within the SPAR had never been repaired and instead only had laminate over it to create a reinforcement. There were also parts of the laminate found to be unbonded to the blade surface due to incorrect keying up of the surface prior to laminating. Once the SPAR defect was removed, it was chamfered and laminated using x14 layers of Uni-Directional fiberglass. Covering Biaxial laminations were then applied. Due to the original crack being extremely fragile, the external chord ways crack was reinforced externally using Biaxial cloth in order to provide a backing plate to complete the core replacements internally. The trailing edge Uni-Directional fibres were also affected with a crack being discovered that had not been repaired at all previously. This was also removed, chamfered, and laminated.
• External repair completed via rope access.
• X14 layers Uni-Directional SPAR laminations completed with covering Biax.
• Uni-directional and Biaxial laminations completed across an area of approx. 2m x 4m.
Internal Repair
As a result of already knowing that all layers were affected within the blade make up, defective laminate and core removal process could begin straight away. In total there were x4 core replacements completed due to the angle of the internal crack. Once again, the internal SPAR crack had only been reinforced previously and had not properly eliminated. This was removed, chamfered and x12 layers Uni-Directional laminate applied. Core replacements were also profiled and surrounding laminate chamfered in preparation for covering Biaxial laminations. Web foot curve was also reinstated to reduce the angle for the covering Biax. Covering Biaxial laminations were applied, and internal repair was now complete. Turbine was then returned to service and running at full capacity immediately after team demobilised.
• X4 internal core replacements completed.
• X12 Layers Uni-Directional fibreglass replaced on SPAR with covering Biaxial laminations also completed.
• External laminate profiled and painted to complete. No filler applied due to climatic conditions and time saving. This had no effect to the blades aero profile due to being so close to the root.
• Turbine running at maximum output immediately after team demobilisation.
Before any repairs could be started, all previous repairs had to be removed to restore blade back to its original profile. Once all previous repairs had been removed, it was discovered that the original crack within the SPAR had never been repaired and instead only had laminate over it to create a reinforcement. There were also parts of the laminate found to be unbonded to the blade surface due to incorrect keying up of the surface prior to laminating. Once the SPAR defect was removed, it was chamfered and laminated using x14 layers of Uni-Directional fiberglass. Covering Biaxial laminations were then applied. Due to the original crack being extremely fragile, the external chord ways crack was reinforced externally using Biaxial cloth in order to provide a backing plate to complete the core replacements internally. The trailing edge Uni-Directional fibres were also affected with a crack being discovered that had not been repaired at all previously. This was also removed, chamfered, and laminated.
• External repair completed via rope access.
• X14 layers Uni-Directional SPAR laminations completed with covering Biax.
• Uni-directional and Biaxial laminations completed across an area of approx. 2m x 4m.
Internal Repair
As a result of already knowing that all layers were affected within the blade make up, defective laminate and core removal process could begin straight away. In total there were x4 core replacements completed due to the angle of the internal crack. Once again, the internal SPAR crack had only been reinforced previously and had not properly eliminated. This was removed, chamfered and x12 layers Uni-Directional laminate applied. Core replacements were also profiled and surrounding laminate chamfered in preparation for covering Biaxial laminations. Web foot curve was also reinstated to reduce the angle for the covering Biax. Covering Biaxial laminations were applied, and internal repair was now complete. Turbine was then returned to service and running at full capacity immediately after team demobilised.
• X4 internal core replacements completed.
• X12 Layers Uni-Directional fibreglass replaced on SPAR with covering Biaxial laminations also completed.
• External laminate profiled and painted to complete. No filler applied due to climatic conditions and time saving. This had no effect to the blades aero profile due to being so close to the root.
• Turbine running at maximum output immediately after team demobilisation.
What the client had to say...
We recently worked with Bladestar Renewables for extensive blade repairs on one of our blades with the notorious chord ways cracks, and we could not be more satisfied with their performance. The team demonstrated exceptional expertise and professionalism throughout the entire process.
From the initial inspection to the completion of the repairs, their attention to detail and commitment to safety were evident. The quality of their work has ensured the optimal performance and longevity of our turbine blades.
We were particularly impressed by their efficiency in minimising downtime and their clear communication at every stage. It is rare to find a service provider with such a high level of technical skill combined with outstanding customer service.
We highly recommend Bladestar Renewables to anyone in need of reliable and high-quality wind turbine blade repairs.
Michael Blohm
Rotor Blade Engineer