Detecting Flaws in the Presence of Strong Geometry Signals in F100 Gas Turbine Engine Components
The inspection of F-100 gas turbine engine components using the Retirement For Cause (RFC) Eddy Current Inspection Station includes the requirement to scan three common but critical geometries: Antirotation windows (ARW), antirotation tangs (ART) and the live rim (LR) area at the component rim, as shown in Figures 1 and 2. These geometries have a common feature — edges, as shown in Figure 3 — that presents a challenge to successful inspection. The edges are sources of strong geometry signals that often have a higher amplitude than flaw signals, thus making a conventional amplitude inspection technique difficult. Therefore, a “frequency select” technique was developed which uses the frequency difference as a flaw determination criteria [1,2]. Using this technique, the RFC System has successfully detected both EDM notches and fatigue cracks in these geometries located in engine components fabricated of IN-100, waspaloy and titanium.
KeywordsFatigue Crack Fast Fourier Transform Frequency Difference Index Direction Threshold Technique
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