On the effect of mass and stiffness unbalance on helicopter tail rotor system behavior

Purpose - This study aims to investigate the effects of mass and stiffness imbalance in a tail rotor induced by damage in forward flight.Design methodology approach - An aeroelastic analysis based on finite element in space and time and capable of modeling dissimilar blades is carried out to study the effect of damage occurring in one, two, and three blades in a four-bladed tail rotor system in forward flight. The effect of damage growth on vibratory hub loads and blade responses is studied using a comprehensive aeroelastic code.Findings - The diagnostic chart which is the summary of damage analysis of tail rotor shows that the root hub vibration spectrum gives enough indication to predict damage growth in the tail rotor blade. Hence, this can be useful towards development of health monitoring system for tail rotor blades.Originality value - The proposed analysis helps in understanding the basic physics behind the damaged tail rotor and also gives qualitative assessment of damaged tail rotor where obtaining the flight test data with damaged tail rotor is difficult.