What property owner Richard Schertz described as the thunderous sound of a wind turbine blade crashing down into his cornfield apparently echoed around the world.

What property owner Richard Schertz described as the thunderous sound of a wind turbine blade crashing down into his cornfield apparently echoed around the world.

The stock price of the company that manufactures the turbines, India-based Suzlon Energy, tumbled more than 39 percent on the Bombay Stock Exchange on Friday after it notified the exchange of the failure.

"This is an extremely rare and unusual incident," the notice said in part. "The cause of this incident is presently under detailed investigation."

Schertz has said he heard the 140-foot fiberglass blade, weighing 6 1/2 tons, come crashing to the ground about 9:30 a.m. Wednesday. It broke off at the stem where the blade connects with the turbine and landed approximately 150 feet from the base of the tower.

AgriWind LLC operates a small-scale wind farm composed of four 2.1 megawatt turbines on Schertz's property southwest of Wyanet, which is about 55 miles north of Peoria in Bureau County. Schertz said one of the turbines has not been rotating since the summer because it was found to have cracks in it. Schertz also said all four turbines have been taken out of operation since the blade broke.

The notice rendered to the Bombay Stock Exchange, however, said "other turbines owned by that customer and our other customers at various locations in the U.S. are operating without interruption. . ."

A Suzlon representative told the Journal Star the blades on all four turbines were scheduled to be replaced within a week because of a design defect that caused cracks in the blades.

The company, which was formed in 1995, announced in March that it would initiate a retrofitting program for 1,251 blades that were determined to have the defect. The company said at the time that 930 of the blades had been installed and the remaining blades were in transit or inventory.

The frequency with which those blades have experienced similar failures is unclear because there is no official tracking mechanism.

The American Wind Energy Association keeps tabs on turbine failures, but that definition could run the gamut from mechanical failure to total tower collapse. A spokesperson for that company said a handful of broken blades and tower collapses have been reported to the agency over the last year.

The Industrial Wind Action Group, a network of people who oppose wind farm installations near population centers and seek to raise awareness about what they deem the inefficiency of wind power, has reported 15 "catastrophic" failures over the last year.

Lisa Linowes, executive director of the group, said the failure in Wyanet is evidence that wind energy isn't as safe as its proponents claim.

"This whole thing about safety worries us a lot," she said. "In the last year, there have been at least 15 cases, and those are just cases that have been reported."

Three of those 15 cases involved broken blades, while a fourth, most recently, involved a tower collapse. In that instance, in Vermont, a blade apparently broke off a tower during high winds, struck the supporting structure and forced it to buckle.

"There are accidents that are happening, that's for sure," Linowes said. "Our fear is that someone is going to get hurt eventually, if not already."

The remaining cases documented by Wind Action center on what appears to be a much more common cause of turbine failure: fire. Eleven of the 15 cases tracked by the group in North America list lightning or another ignition source as the cause of blazes that begin hundreds of feet in the air.

One such event occurred last year at the Twin Groves wind farm operated by Horizon Wind Energy in eastern McLean County. Despite countermeasures such as lightning rods meant to divert a strike from the turbines, one tower had to be shut down because of lightning and a resulting fire.

"It's unusual, but it does happen," said Steve Lange, director of regional operations at Twin Groves.

Lange said the company has not installed any Suzlon products in its multiple facilities across the country, though it planned to use Suzlon turbines at a proposed Oregon wind farm. Horizon's operating facilities use equipment made by Vestas and General Electric.

"They've been in the business for a long time, and they have a good track record," Lange said. A failure like the one in Wyanet "is nothing we've experienced at Horizon."

Matt Buedel can be reached at (309) 686-3154 or mbuedel@pjstar.com.