An ultrasonic scanning system for testing large curved components of fiber/resin matrix composite material, the system ultrasonically testing these components with water jet probes caliper-mounted on the working arm of an industrial robot. The computer reads CAD data appertaining to the component, transfers it to robot-compatible form and delivers it on demand to the robot computer. The computer also reads the data output from the probe and reconciles it with the CAD data to yield as an output a quality map of the component. Instantaneous probe position on the surface of the work piece is computed from data on the starting position of the scanning movement of the probe, and the scanning velocity of the probe.