The blade of a wind turbine breaks


The policyholder designs and manufactures small wind generators. The damaged wind turbine featured a horizontal shaft with 3 blades and was being tested to verify operation and validate the power curve.

The insured company had sold several of the turbines to a client in Italy, with production due to start as soon as the prototype was validated.

Although the wind was not particularly strong (about 50 km/h), an 8-metre blade broke and fell to the ground. The machine continued to rotate for several minutes. Due to the rotor becoming imbalanced when the blade came off, extensive structural damage was caused to the wind turbine’s equipment pod and steel mast.


The GM Consultant loss adjusters soon observed that there were significant production defects in the blades: the epoxy resin had not properly impregnated the fibres, the layers were different thicknesses, and there were empty spaces in the blade. An analysis of the blade manufacturer’s processes revealed notable inadequacies. The loss adjusters launched an appeal against the manufacturer.

To successfully complete their mission, the loss adjusters carried out a full analysis of the dimensioning of the machine in accordance with standard IEC 61400-2. A review of the entire contractual chain between all parties involved (design offices, subcontractors, etc.) was also necessary.

The loss adjusters noted that the fatigue design of the blades was grossly inadequate. However, it was revealed that the policyholder, as designer and integrator of the machine, was responsible for verifying the machine’s mechanical strength. In addition, the safety devices in case of blade breakage were inadequate. Therefore, although the manufacturing method for the blades was faulty, the appeal could not be successfully concluded.