Robotized phased-array inspection of sandwich-structured aircraft components

be challenging. The manual inspection techniques usually used in this context are time-consuming and can lead to inconsistent results. L3Harris and the Centre Technologique en Aérospatiale (CTA) have developed a novel robotized solution to conduct efficient ultrasonic inspection of sandwich-structured components. The system is based on collaborative robots to enhance safety for both components and operators and uses custom-made probe-holders designed to achieve smooth scanning movements and proper coupling conditions. This paper focuses on the ultrasonic aspects of the solution: customized phased-array probes, specific firing sequences and novel data analysis techniques. The objectives were to reduce the inspection time, lower the number of different probes and passes required to cover the full components, obtain complete ultrasonic images of the components ensuring data traceability over time, and provide guidance for the diagnostic. The solution uses a pair of custom 1.5D linear phased-array probes mounted on conformable wedges. The firing technique varies the active aperture during the scan. This allows for simultaneous acquisition of pulse-echo (PE) data in the lower and upper skins, and through-transmission (TT) data through the sandwich, during a single pass. A novel analysis algorithm was developed to automatically compare the collected A-scan signals in each of the three available channels (PE top, PE bottom and TT) to reference signals. Depending on the similitude of the signal triplets with the references, each inspected pixel can be classified in one situation (pristine or defective) and color-coded accordingly. A diagnostic map is then generated and can be used by the inspector in correlation with more classical data (A-scans, B-scans, and C-scans) to make an informed decision.