Abstract: A plurality of ultrasonic transducers mounted linearly on a belt that is contained and supported by a housing. The housing has wheels and handles mounted on its sides to allow an operator to grasp the apparatus and roll it across the surface of a test object along a line normal to the belt. The transducers are electrically connected to various devices which enable pulse echo testing to be performed on the test object and make the results immediately available as a picture either on paper or on a video monitor. The belt is moved laterally and cyclically back and forth as the apparatus is rolled longitudinally and the transducers are sequentially excited to emit ultrasonic waves, thus testing a swath having a width equal to the extremes of lateral motion of the line of transducers. A dynamic counterbalance swings 180.degree. out of phase with the cyclic motion of the belt, and serves to damp out the vibration generated by the belt's motion.