Poor maintenance has been blamed for the collapse in January of a 1.3 MW wind turbine supplied by Siemens Wind Power for Eurus Energy's 32.5 MW Iwaya wind farm on the northern Honshu island (Windpower Monthly, February 2007). The company says one of the turbine's blades was incorrectly fitted. Workers were supposed to have attached the blocks regulating the angle of the blades with two bolts each, using a torque wrench, but on one blade just a single bolt was fixed, using the wrong tool, the company acknowledges. Investigators say that as a result the components designed to regulate the pitch of the blades fell off, damaging the turbine's hydraulic system and allowing the blades to shift into a position perpendicular to the wind, which was blowing at 25.8 m/s just before the mishap. This increased the blades' lift to a point where the 62 metre rotor accelerated past its sustainable rate, causing the tower buckle near its base. An automatic alarm system, design to alert maintenance staff to faults, was working, but workers did not notice the alarms going off, the company says. In an apology to local residents, the company says it will take measures to prevent similar malfunctions and improve response to warning alerts.
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