Radial impellers made of continuous fibre-reinforced composite material in modular design are spin rig tested until failure up to 538 m/s. Using high-speed recordings during the test and fracture analysis, it is possible to interpret the damage and failure behaviour of the structure and compare it with the results of the numerical simulation. One focus of the discussion is on the chosen joining technique as a relation to the bursting speed. This provides indications for measures to further improve the design and increase the performance and reliability of such structures.