Ultraviolet sensing of the condition of the vanes and blades of gas turbines in service

A method and apparatus for monitoring the condition of the thermal barrier coating on turbine blades and vanes is provided. The coating is monitored with ultraviolet sensors which can detect ultraviolet radiation emitted from electrical discharges and glow coronas at the surface of the blades and vanes. Such electrical glow discharges and coronas are the result of friction electricity found at the surface of blades and vanes, and are also due to the high pressure, temperature and velocity conditions within the turbine. As the thermal barrier coating deteriorates, the electrical discharges and glow coronas and associated UV emissions decrease in magnitude or have other characteristic changes, thus permitting monitoring of the corona to detect changes in the coating over time.