Costly repair mistakes

In every operational season, our teams face a challenge we would much rather avoid: correcting faulty – and sometimes fundamentally incorrect – repairs. This year alone, we have dedicated countless hours to removing laminations performed in gross violation of repair manuals. Below is a case study that serves as a warning for every wind farm manager.

Error Analysis: Theory vs. Reality

In this specific project, instead of a correct, precise repair using 2 layers of BX (bi-axial) glass fiber, we discovered a build-up of 5 layers of UD (uni-directional) fiber, all of identical size. While a layman might assume “more means stronger,” in composite technology, this is a cardinal error. Primary Technical Failures:

• Incorrect Material Selection: Using uni-directional (UD) fibers where bi-axial (BX) reinforcement was required completely altered the blade's load distribution.
• Lack of Tapering: Incorrect staggering of fiber distances at the edges of the repair.
• Local Stiffness (Hard Spot): Excessive material created a rigid zone within the flexible laminate. Under operational stress, this inevitably led to cracking.

Timeline and Consequences

Due to a faulty intervention, a minor defect escalated into two large cracks at the ends of the “rigid patch.” What does the additional workload look like in such cases?

• Day 1: Inspection and diagnosis. Preparation of correct materials.
• Day 2-3: Grinding, surface preparation, and structural restoration according to the manufacturer's manual.
• The Result: Over 2 additional working days of turbine downtime, plus necessary night-time curtailments.

Technical Summary

In this case, the final cost and operational time increased several-fold-a direct result of having to remove the unprofessional overbuild left by a previous team. However, in wind turbine blade service, the margin for error is much tighter than just service budget losses or a 2-day schedule delay.

• Structural Component Damage: Uncontrolled crack propagation, initiated by a poor repair, can quickly lead to a loss of integrity for the entire blade.
• Safety Hazards: The risk of shell delamination or a total blade failure poses a direct threat to the farm infrastructure and colossally increases investor losses.