Abstract: During the life extension inspection of the turboprop engine, the first, second and third stage turbine blades were found to have pits and scratches. In this paper, the appearance inspection, metallographic structure inspection and energy spectrum analysis of the severely damaged turbine blades were carried out, and it was found that the turbine blades are scratched by the impact of iron-based metal objects. After disassembly and inspection of the engine, it was determined that the cause of the damage was that the residual weld bead of the support plate of the combustion chamber fell off during engine operation, and the dropped weld bead damaged the blade under the action of high-speed airflow. Improving the combustion chamber welding process and refining the surface quality inspection requirements of welded parts can effectively avoid such problems.