11月21日，位于美國加利福尼亞州南部Ocotillo風場的一臺西門子機組發(fā)生倒塔事故，事故機型為Siemens 2.37MW-108，西門子方面透露的此次事故初步調查結果顯示：由于葉片內部抗剪腹板出現裂紋導致此次倒塔事故。 　　
　　相關報道
　　
　　Blade blamed for Cal collapse
　　
　　Cracks lead to collision with tower at Pattern Energy’s 265MW wind farm
　　
　　Investigators believe blade cracks resulted in the collapse of a Siemens 2.37MW-108 SWT turbine at Pattern Energy’s 265MW Ocotillo wind farm in southern California.
　　
　　Preliminary root cause analysis carried out by Siemens has concluded that cracks in the “structural member of the interior of the blade known as the shear web” caused it to strike the tower, which then lead to the tower collapsing last month.
　　
　　“This type of crack is slow to develop and can be seen via visual inspection of the inside of the blade prior to progressing to failure,” the wind farm owners said.
　　
　　It added that this is the first time a fault of this nature has occurred to this blade type and is “unrelated” to a blade failure at the facility in 2013.
　　
　　Siemens is currently conducting internal inspections of all the wind farm’s turbines, which will only be returned to service “after confirming this type of incident is unlikely to recur", the owners said.
　　
　　Ocotillo comprises 112 Siemens turbines and has been fully operational since July 2013.
　　
　　Electricity generated by the wind farm is sold to San Diego Gas & Electric under a 20-year power purchase agreement.