Automated Eddy Current Inspections For Turbine Engine Component Life Extensions

This paper discusses the design, development, and anticipated benefits from the development of a fully automated eddy current inspection (ECI) system for the Army. A direct application for the ECI system will be the Army’s T700-GE-700 helicopter engine. The T700 engine’s critical rotating components have life limits based on analytical models assuming minimum material properties. Currently, the Army utilizes standard fluorescent penetrate inspection (FPI) to detect cracks in parts caused by use, handling, and/or manufacturing error. The aviation community has determined that FPI is inadequate to fully inspect critical components. In order to fully inspect critical hardware, the Army, along with the Air Force, General Electric, and Veridian, is developing a fully automated ECI system for the gas generator turbine (GGT) module of the T700. The small physical part size of T700 hardware has led to the development of new eddy current probes and new inspection techniques. The Army is designing the inspection system to permit life extension of the GGT components for an additional 1500 hours of operation. This paper discusses the design challenges, the new probes developed, and the new inspection techniques utilized in achieving the 1500 hour life extension for the T700-GE-700 GGT.