DES MOINES, Iowa - MidAmerican Energy is looking into the problem that led to blades from its wind turbines breaking off twice in the last month.
MidAmerican spokesperson Geoff Greenwood says they've temporarily shut down 46 turbines at several wind farms.
He says their checking the lightning protection systems after lighting struck especially close to both turbines that lost their blades.
The most recent occurrence took place in Greene County on Thursday, while the first happened in Adair county in September.
Greenfield said the incidents are "extremely rare" while acknowledging that even one incident is not acceptable.
The blades themselves, which fell into farm fields, weigh about 18-thousand pounds.