An apparatus for the ultrasonic testing of internal areas of prefabricated composite assemblies as described. The composite assemblies have one or more internal areas formed therein. The apparatus includes at least one receive transducer, at least one transmit transducer, a vertical member, a support member slidably attached to the vertical member, a pair of substantially parallel hollow rods, and an ultrasonic testing system. Each rod comprises a transducer attachment end with receive transducers attached to the transducer attachment end of a first rod, and transmit transducers attached to the transducer attachment end of a second rod. The rods are slidably attached to the support member and manually movable with respect to a composite assembly to be tested. The ultrasonic testing system is coupled to the receive transducers through the first rod, and coupled to the transmit transducers through the second rod.