This study focuses on the failure of blades which is one of the critical parts of the compressor and turbine. Experiments are performed on the aero-engine compressor blade model of dovetail joint using the technique of photoelasticity. First, the high-stress concentration zone is found. This is along the contact surface of the blade and disc. Two different configurations of cracks located in this zone are studied further. The stress intensity factors for mixed mode loading are evaluated using over-deterministic nonlinear least squares approach. © 2020, Springer Nature Singapore Pte Ltd.