Patent ID: 7990547

Claim:
A method of measuring erosion of an edge of a turbomachine aerofoil, the method comprising the steps of:— a) directing light from a source of light in a plane across a position on the edge of the turbomachine aerofoil, b) detecting the light reflected from the position on the edge of the turbomachine aerofoil, c) analysing the light reflected from the position on the edge of the turbomachine aerofoil, d) measuring the distance from the light source to points on the edge of the turbomachine aerofoil at the position on the edge of the turbomachine aerofoil to produce a profile of the edge at the position on the edge of the turbomachine aerofoil in terms of x and z coordinates, e) calculating the distances of points on the edge of the turbomachine aerofoil from a centroid of the profile, f) detecting local peaks in the distance of points from the centroid of the profile, g) selecting the two local peaks with the greatest distance there between, h) determining the distance between the two local peaks, i) fitting a first straight line between the two local peaks, j) fitting second and third straight lines onto both sides of the profile of the edge at the position on the edge of the turbomachine aerofoil, k) determining the distance between the points of intersection between the first straight line and the second and third straight lines and l) comparing the determined distance between the points of intersection between the first straight line and the second and third straight lines and a predetermined distance to determine if the edge of the turbomachine aerofoil has unacceptable erosion.