Development of a liquid couplant free contact ultrasonic test system for bond evaluation of solid propellant grain of rocket motor igniter

Certain igniters of solid rocket boosters were made by casting propellant inside paper restrictor tube. Debonds may occur within paper tube as well as in the paper tube / propellant interface. Radiographic and Dry scan ultrasonic methods were unable to map as well as locate debonds. Ultrasonic pulse echo method was capable of mapping as well as locating debonds in this product but was not used because of liquid couplant which harms the product. Studies were conducted to develop a solid couplant material based on Silicone rubber based compunds. Replaceable solid couplant faces were designed and fabricated for conventional transducers. Inspection procedures were generated and standardised.