Abstract: Single-crystal components of gas turbine engines, like turbine blades, are inspected in the installed state within the engine for cracking in certain critical areas using longitudinal ultrasonic waves. A first, rough orientation of the ultrasonic waves onto the critical area is accomplished under camera-visual control using an ultrasonic probe whose shape conforms to the respective component area and which, therefore, can be form-fitted to the component. For fine-positioning of the ultrasonic waves in the critical area, a reference signal is generated at a component-specific geometrical contour adjacent to the critical area by second ultrasonic waves emitted at a local distance to the first ultrasonic waves. The presence of this signal ensures the safe, disturbance-free detection of cracks in the critical blade area by means of longitudinal sonic waves. The invention includes an apparatus for the performance of the method.

Abstract: The present invention provides an ultrasonic transducer structure, comprising a first ultrasonic transducer element (1), arranged and operable for transmitting an ultrasonic signal from a front face of the structure, damping material (2) at the back of the first ultrasonic transducer element (1), and a second ultrasonic transducer element (3) in or on the damping material behind the first ultrasonic transducer element (1), arranged and operable to receive sound energy propagated through the damping material (2) when the first ultrasonic transducer element (1) is operated to transmit an ultrasonic signal from the front face.

Abstract: The present invention provides an ultrasonic transducer structure, comprising a first ultrasonic transducer element (1), arranged and operable for transmitting an ultrasonic signal from a front face of the structure, damping material (2) at the back of the first ultrasonic transducer element (1), and a second ultrasonic transducer element (3) in or on the damping material behind the first ultrasonic transducer element (1), arranged and operable to receive sound energy propagated through the damping material (2) when the first ultrasonic transducer element (1) is operated to transmit an ultrasonic signal from the front face.