INTRODUCTIONThe Hydra-70 uses small solid rocket motors, which are produced in large numbers. It is used by all branches of the US armed forces and those of several other countries. A research and development program was initiated in 1994 which had the objective of improving the quality of the motors. The motors use solid fuel grain and the effort reported in this paper focuses on providing motors with higher reliability in terms of performance and safety, and at the same time achieving a significant reduction in inspection costs.The complete QA program for the Hydra-70 rocket motor considers all aspects of the life cycle. It considers motors at the time of manufacture and those in the stockpile. The analysis consideres the manufacturing process, defect analysis, physical and chemical testing, current real-time radiography (RTR), analysis of effects of aging, live firings and the use of ultrasonic testing. This paper reports aspects of the ultrasonic element of the program. BACKGROUND

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