More than two weeks after the collapse of a Vestas wind turbine at ScottishPower's Beinn an Tuirc wind farm on Kintyre in Argyll and Bute, the supplier says it is still investigating the cause. The tower of the V47 machine, rated at 660 kW, folded over on November 8, bringing the nacelle and blades crashing to the ground. The turbine parts -- including its "black box" -- have been taken to offices in the UK for analysis, says Vestas' Peter Kruse. The incident apparently took place during heavy winds. The Met Office weather station at nearby Macrihanish reported gusts of 31 m/s, but stronger winds have been experienced at the exposed wind farm site over its past six years of operation. Until the cause of the incident is known, the UK Health and Safety Executive has called for adjustments to the operation of similar turbines in Scotland. For the time being Vestas is advising that the cut-out wind speed on the V47 and V52 models be reduced from 25 m/s to 15 m/s. A tower can fold after being struck by a passing blade if a turbine is not operating as it should.