An apparatus and method for inspecting a structure are provided which include probes with sensing elements and are disposed proximate the opposite surfaces of a structure, where only one of the probes need be driven. A tracking probe may be magnetically coupled to a driven probe and move in coordination therewith. Ring magnets may be used in the driven and tracking probes to provide the magnetic coupling and align sensing elements disposed in the centers of the ring magnets. The probes include ball bearings such as ball and socket bearings for supporting the structure and maintaining the desired orientation and spacing of the probes relative to the structure. A fluid, such as water or pressurized air, may be used as a couplant between an ultrasonic transducer and the structure. A water column skirt may be used to with a probe employing ball bearings for support.