Automated Air-Coupled Ultrasonic Technique for the Inspection of the EC145 Tail Boom

Usually ultrasonic testing of complex aerospace components is carried out with squirter technique. However, water coupling delivers disadvantages like pressure variations, air-bubbles, limescales, algae and corrosion of the mechanics. Therefore a non-contact technique is preferable which avoids these disadvantages. The air-coupled ultrasonic technique large acoustical mismatch between air and solids can be reduced with special transducers in connection with special transmitter and receiver techniques. In spite of these optimisations the test frequencies have to be lower than 1 MHz. It has been already published that low ultrasonic frequencies are necessary for the inspection of CFRP sandwich components (even with water coupling). The air-coupled ultrasonic testing technique has been qualified for testing CFRP honeycomb sandwich structures. Because of the vertical alignment of the transducers on opposite sides of a complex component a ten axis robot scanning system is necessary. This paper presents first results and details of the automated air- coupled robot ultrasonic imaging system which is in operation by Eurocopter in Donauworth since 2011. This project has been a co-operation between Eurocopter Deutschland, Robo-Technology, EADS Innovation Works, Ing. Buro Dr. Hillger, and Ostertag. 4th International Symposium on