Cable failure resulted in the crash of a trainer aircraft

A training aircraft was crashed during a training session. The pilot and the trainer ejected out before the crash. The aircraft was elucidating the spin and recovery motion in the air. During a spin motion the aircraft did not recover and crashed to the ground. Rudder and elevator cables were found failed in initial investigation. They were seemed to be failed before crash. The failed cables retrieved from the crashed aircraft as well as un-failed used cables from the in-service aircrafts were subjected to further analysis. The results revealed that more than 50% wires of a rudder cable was failed under the fatigue mechanism and fractured catastrophically rendering the rudder out of order. The material of this particular cable was also different from the other un-failed/failed cables having comparatively lower mechanical strength. The pilots applied the rudder controls for recovery from spin motion, but could not find it operational. The aircraft crashed due to failure of rudder cable. The failure of other cables was the after effects of the impact of aircraft to the ground.