Behind nacelle doors

Paul Dvorak

Mike Rowe produces the engaging TV show “Dirty Jobs” rightfully named for the vile work he takes on. Rowe bravely spends the day doing the dangerous to the disgusting, from removing snakes from ponds to cleaning sewers, all for our entertainment.

One not-so-disgusting but eye-opening job had him spend a day as a wind turbine technician. The trip starts with an 80-m climb. The techs almost ran up the ladder while Rowe and his crew climbed at a much slower pace. It looked exhausting, and when in the nacelle, Rowe found it hard to move about its tight confines. By comparison, claustrophobic WWII submarines are absolutely spacious.

Rowe’s first task was cleaning pools of oil that dripped from hydraulic yaw brakes. The crew seemed unperturbed, as if the pools were normal. They cleaned up easily enough with spray soap and rags.

The next step was changing an oil filter. A tech handed Rowe an adjustable wrench and told him to loosen the bolt at the bottom of a filter mounted near the nacelle floor. But Rowe found the task utterly daunting. His usually unflappable demeanor showed genuine irritation. Not willing to admit defeat, he grabbed a small video camera from his crew and pointed it at the difficult-to-see bolt so we could all view the problem on a small screen. The techs were toying with Rowe. A socket-head wrench was the tool needed to turn a bolt at the center of some crenellations. With the right tool, the bolt was soon loose, but getting the end cap off was another matter. It eventually came loose with one of the heftier guys lying on his back grunting with a torque bar.

Then Rowe moved to a forward section of the nacelle, accessed through a small opening. In the close confines, he could not see where he was stepping and had to be guided by another tech already in the space. In this tight enclosed area, they cleaned up a grease spill with brake cleaner, a solvent. Rowe also found a few crickets in the grease, though this was nothing compared to the rattlesnake one tech reportedly encountered. Two fang marks were still visible on his hand. The bite resulted in the tech’s hasty retreat and several days in the hospital. He theorized the snake crawled into the nacelle before it was lifted and then it found the warm generator to its liking.

To most, the show was simply entertainment. To engineers, it was outrageous. Who in their right mind would so badly design equipment for small spaces? Designfor- maintenance, an aspect of design work, seems completely omitted from this turbine and most likely many others. The tight work space in the nacelle is not only irritating, but primed for accidents.

For instance, using a torque arm in a difficult position needs one slip, and boom: a broken tooth. Small access holes beg for slips and falls. Using a solvent in closed quarters is practically praying for a pass-out, and why so much dripping hydraulic oil?

A recent report from Wind Energy Update tells of rising O&M costs and it’s no wonder. The lowest cost-to-build turbine is not the lowest cost overall. More spacious nacelles designed for maintenance will improve working conditions and hopefully, keep turbine maintenance off Dirty Jobs.

–Paul Dvorak