The University of Dayton Research Institute (UDRI), under contract by the U.S. Air Force, has designed and constructed a fully automated ultrasonic inspection system for the detection of embedded defects inside in-service gas turbine engine disks. This system uses many new approaches that conduct automated ultrasonic inspections to produce highly reliable engine disk inspections without human involvement. The ultrasonic inspection system incorporates off-the-shelf, industry standard components typically not found in NDI systems, that have been integrated using a modular-architecture approach to produce a system capable of sustained operation in an Air Force depot environment. Designed to he rugged and easily maintained, the system consists of a six-axis articulated robotic arm, rotating water tank, phased-array ultrasonic instrument, automated probe changing of 'smart' probes, collision avoidance hardware, PC-based industrial computer, Windows-based operating system, digital vision system, and a specialised water management system that eliminates air bubbles in the water. The robotic manipulation of the probes allows ultrasound to be directed at almost all features of the engine component. Use of the phased-array ultrasonic instrument and probes allows for optimisation of both the sensitivity and resolution for each inspection through electronic beamforming, scanning, and focusing processes. The system requires an operator to load the part, and then conducts all parts of the inspection automatically. including part recognition, part dimensioning, probe changing, probe calibration, inspection, and accept/reject decisions. This paper discusses the components and specifications of the system and technology improvements over conventional systems that have been incorporated.