Many of the GE 7FA based combined cycle power plants built in the late 1990’s / early 2000’s, experienced oil contamination issues, primarily due to the requirements placed upon the lube / control oil system.  Varnish and particulate contamination resulted in downstream impacts, especially within electrohydraulic servos and their small diameter control orifices.  Parker’s Abex line of Jet-Pipe® servos has proven to be a robust alternative to the OE servo valves.