A computer implemented method of determining the ultrasonic inspectability of a supplied part out of which a final component is to be machined, the method including the step of providing a set of inspection rules for ultrasonic inspection of the supplied part; characterised in that it further comprises the steps of: providing an input geometry for the supplied part in the form of at least one 2D polygon, the supplied part being ultrasonically inspectable by scanning an ultrasonic probe at one or more different ultrasound beam angles along faces of the supplied part corresponding to polygon edges of the input geometry, whereby a complete ultrasonic inspection of the supplied part comprises a number of scans equal to the sum, over all the edges, of all the beam angles used for a given edge; providing a target geometry which is at least one further 2D form defining the shape and position of the machined final component within the input geometry; for each edge of the input geometry, determining a respective allowable region of the input geometry that defines those parts of the input geometry which can be ultrasonically inspected from that edge without infringing the inspection rules; for each combination of a given ultrasound beam angle and a given edge of the input geometry, determining a respective limitation shape which is bounded at one side by the given edge and extends from that edge in the direction of the beam to a boundary at a penetration depth of the ultrasound in the input geometry; for each edge of the input geometry, combining the one or more limitation shapes for that edge with the allowable region for that edge to determine one or more inspectable regions of the input geometry associated with that edge, each inspectable region thereby corresponding to a respective one of the scans of the complete ultrasonic inspection; and overlaying the inspectable regions in their relative positions on the target geometry, whereby the supplied part is determined to be ultrasonically inspectable when all parts of the target geometry are overlayed by at least a predetermined minimum number of the inspectable regions. providing an input geometry for the supplied part in the form of at least one 2D polygon, the supplied part being ultrasonically inspectable by scanning an ultrasonic probe at one or more different ultrasound beam angles along faces of the supplied part corresponding to polygon edges of the input geometry, whereby a complete ultrasonic inspection of the supplied part comprises a number of scans equal to the sum, over all the edges, of all the beam angles used for a given edge; providing a target geometry which is at least one further 2D form defining the shape and position of the machined final component within the input geometry; for each edge of the input geometry, determining a respective allowable region of the input geometry that defines those parts of the input geometry which can be ultrasonically inspected from that edge without infringing the inspection rules; for each combination of a given ultrasound beam angle and a given edge of the input geometry, determining a respective limitation shape which is bounded at one side by the given edge and extends from that edge in the direction of the beam to a boundary at a penetration depth of the ultrasound in the input geometry; for each edge of the input geometry, combining the one or more limitation shapes for that edge with the allowable region for that edge to determine one or more inspectable regions of the input geometry associated with that edge, each inspectable region thereby corresponding to a respective one of the scans of the complete ultrasonic inspection; and overlaying the inspectable regions in their relative positions on the target geometry, whereby the supplied part is determined to be ultrasonically inspectable when all parts of the target geometry are overlayed by at least a predetermined minimum number of the inspectable regions.