Investigation into the fall of a GE 1.5 MW turbine at the 49.5 MW Caluengo wind plant in Navarra discards the possibility of a series fault. As a precautionary measure the plant was shut down for five days but nearly all Caluengo's 33 machines were back in operation in mid January following "exhaustive checks," says owner-operator Desarrollos de Energías Renovables de Navarra (Derna). "The fault has been located to the electrical feed device of the turbine's electronic pitch control system," says Derna. The pitch control alters the angle of the blades relative to the wind, varying wind resistance and controlling power output. At a time when blades on the other turbines were pitched in response to high winds, the failed turbine spun out of control until the tower snapped half way up. Both Derna and GE describe it as an isolated incident. Derna is a 50-50 joint venture between Corporacion Energía Hidroeléctrica de Navarra and Desarrollos de Energías Renovables SA.