For the unexpected tip failure of hollow fan blade HCF test

the stress distribution test

vibration simulation and crack analysis were done. The test results indicate that the failure region is not the high stress region

and fracture analysis indicates that the crack initiates from the welding area of the duct in the blade tip. Validation test on the blades without the tip welding shows that the failure is induced by the welding defect in the blade tip duct. Based on the fatigue analysis and test validation

the failure occurs by improper welding method selection and welding process control in the manufacturing process. Consequently

the improved process is applying the EB welding in manufacturing and CT inspection.