Structural WEB spar repair report - LM 48.8 blade
Repair of structural damage to the WEB spar, discovered during a routine internal inspection of an LM 48.8 blade on a Nordex N90/2500 turbine - full load-bearing reconstruction in approximately 70 working hours.
The project concerned structural damage discovered during a routine internal inspection. After engineering analysis and the decision to immediately stop the Nordex N90/2500 turbine, we proceeded to repair this key structural element.
Workplace specifics
The Nordex N90 in the Beta version imposed a specific division of work between the two teams. Access to the damage zone required passing each time through a ladder system leading into the blade from the front of the HUB. Due to wind conditions that made it impossible to safely pin the turbine overnight, the full set of tools and materials had to be transported into the blade every day and carried back out at the end of each shift. The work was carried out using polyester resin in the narrow space of the blade, which required daily installation of ventilation systems and constant monitoring of atmospheric conditions.
Operation day by day
- Day 1 - preparing the logistics for the entire job, transporting tools and materials to the nacelle.
- Day 2 - surveying the damage, making sketches and the layer layout, and cutting out the defective section of the WEB structure.
- Day 3 - preparing the surface for lamination, stepped grinding of the existing laminate to ensure proper layer overlap.
- Day 4 - assembly work: fitting and bonding the new balsa core insert. The day ended with an urgent halt to work due to a sudden break in the weather and a storm.
- Day 5 - mechanical machining of the bonded section, matting the surface on both sides of the spar, application of structural adhesive, and controlled heat curing of the bond.
- Day 6 - first phase of structural reconstruction: laminating layers on both sides of the spar and heat curing the entire repair.
- Day 7 - closing the lamination: applying the final closing layers and a final quality inspection of the laminate.
Summary
The work was carried out by two parallel teams, which allowed continuity of operations within short weather windows. The total turbine downtime was extended by 3 days due to wind exceeding safety limits (12 m/s). The repair ended with a full reconstruction of the spar's load-bearing capacity over approximately 70 working hours.
