Abstract: Apparatus for determining the location of surface defects on a test piece of electrically conductive material by scanning the surface with at least one sensor arrangement comprising proximity sensors based on eddy current induction. The test piece may be moveable, e.g. advanced, in relation to the holder arrangement which is arranged to move the sensor arrangement in a sweeping or scanning movement from one side of the test piece to the other. The position of the edge of the test piece, is determined successively, e.g. for each scan cycle and the location of detected cracks is calculated with a starting point from the detected edge position.