Abstract: A filter internal flaw test apparatus includes a frame with a filter support and at least one pair of transducer supports. A filter is positioned in the test apparatus, and an ultrasound through transmission test and at least one ultrasound pulse echo test are performed on the filter. Data reliability is increased by positioning the pair of transducers in alignment with one another and pushing them toward one another using a force generator with a predetermined uniform force, such as via a regulated pneumatic actuator. A signal generating/receiving device is in communication with the transducers and provides the ability for analyzing the test results to determine whether the filter has an internal flaw, such as a crack or void that would render it unsatisfactory for use as a particulate filter.