February 27, 2008 | Mark Paradies

Oregon OSHA Releases Report About Fatal Wind Farm Accident

The following is news release by Oregon’s Occupational Safety and Health Division:

The Oregon Department of Consumer and Business Services, Occupational Safety and Health Division (Oregon OSHA) has fined Siemens Power Generation Inc. a total of $10,500 for safety violations related to an Aug. 25, 2007 wind turbine tower collapse that killed one worker and injured another.

“The investigation found no structural problems with the tower,” said Michael Wood, Oregon OSHA  administrator. “This tragedy was the result of a system that allowed the operator to restart the turbine after  service while the blades were locked in a hazardous position. Siemens has made changes to the tower’s engineering controls to ensure it does not happen again.”

The event took place at the Klondike III Wind Farm near Wasco, where three wind technicians were performing  maintenance on a wind turbine tower. After applying a service brake to stop the blades from moving, one of the  workers entered the hub of the turbine. He then positioned all three blades to the maximum wind resistance  position and closed all three energy isolation devices on the blades. The devices are designed to control the  mechanism that directs the blade pitch so that workers don’t get injured while they are working in the hub.

Before leaving the confined space, the worker did not return the energy isolation devices to the operational  position. As a result, when he released the service brake, wind energy on the out-of-position blades caused an  “overspeed” condition, causing one of the blades to strike the tower and the tower to collapse, the Oregon  OSHA investigation found.

Chadd Mitchell, who was working at the top of the tower, died in the collapse. William Trossen, who was on  his way down a ladder in the tower when it collapsed, was injured. The third worker was outside the tower and  unharmed.

During the investigation, Oregon OSHA found several violations of safety rules:

• Workers were not properly instructed and supervised in the safe operation of machinery, tools,  equipment, process, or practice they were authorized to use or apply. The technicians working on the  turbine each had less than two months’ experience, and there was no supervisor on site. The workers  were unaware of the potential for catastrophic failure of the turbine that could occur as a result of not  restoring energy isolation devices to the operational position.

• The company’s procedures for controlling potentially hazardous energy during service or maintenance  activities did not fully comply with Oregon OSHA regulations. Oregon OSHA requirements include developing, documenting, and using detailed procedures and applying lockout or tagout devices to secure hazardous energy in a “safe” or “off” position during service or maintenance. Several energy  isolation devices in the towers, such as valves and lock pins, were not designed to hold a lockout device, and energy control procedures in place at the time of the accident did not include the application and removal of tagout devices.

• Employees who were required to enter the hub (a permit-required confined space) or act as attendants to employees entering the hub had not been trained in emergency rescue procedures from the hub.

Siemens Power Generation has 30 days to appeal the citation.

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