Lightweight constructions offer the potential to save weight and thus climate-damaging CO₂ through less accelerated mass. Complex structures and hybrid material combinations are therefore being used in more and more applications. A key aspect of these structures are the joining processes used to connect different components made of various materials. Adhesive bonds offer great advantages here as a material-locking connection compared to ‘classic’ joining methods, as they can be used to join almost any combination of materials. With the adhesives currently available, high-performance materials can be joined together with high strength without additional components such as screws or bolts. In order to ensure safe operation, quality assurance is absolutely essential after production and during operation of such joints. Non-destructive testing methods, such as non-contact air-coupled ultrasonic testing, offer great potential here. In order to investigate the potential of these methods for defect detection in more detail, different types of defects were introduced on demonstrator components. These are tested using both air-coupled ultrasound and X-ray radiographic testing. It has been shown that pores and insufficiently cured adhesive can be visualized using airborne ultrasound.