The industry started to realize that a basic two-step oil change process didn’t necessarily guarantee clean oil. Also, using buckets up and down tower left a lot of room for contamination of the fresh gear oil. As it became clear that more than a basic oil exchange was needed and the gearbox needed to be flushed, then using a gear oil exchange system is necessary.

In the past, wind turbine companies depended on normal oil analysis iron levels as a determination of a good oil change. It seemed that just draining and filling the gearbox was enough. We know that normal ICP oil analysis can only see particles about five microns in size and smaller, whereas Analytical Ferrography can detect all ferrous particles of all sizes and is a much better evaluation in this case.

A recent field test comparison study was performed on eight turbines and the result was that just draining and filling will leave 50 percent of the particles in the gearbox. The study compared normal ICP iron analysis and Analytical Ferrography in two types of oil change procedures; drain and fill and the four-phase flush procedure. The four-phase procedure left just over .1 percent of wear particles compared to the 50 percent in the two-step drain and fill.

When the benefits of flushing the gearbox were realized, then essentially a single oil change became two or three oil changes at one tower. With the four-phase process, you are vacuuming and dispensing used oil, flush oil, rinse oil, and the final fill oil a number of times.

Over the course of the year starting in 2007, customers went from the basic two tank system to asking about three and four tank systems with flushing capabilities. They weren’t as concerned about how many they could get done; they wanted to know how to replace the oil as cleanly as possible in a multi-step process. Customers didn’t care if they only got one turbine done a day, as long as they ended up with clean oil in the turbine. The industry shifted from quantity to quality