A method of inspecting a test part is provided. The method includes positioning an eddy current probe on a surface of the test part and scanning the test part using the eddy current probe to generate a first signal corresponding to a no lift-off condition of the test part. The method further includes positioning the eddy current probe at a pre-determined distance from the surface of the test part and scanning the test part using the eddy current probe positioned at the pre-determined distance from the test part to generate a second signal corresponding to a lift-off condition of the test part. The method also includes processing the first and second signals to estimate an electrical conductivity of the test part.