A stub shaft for a turbine engine is described in which respective masses are positioned along the stub shaft in a balanced rotation relationship for normal rotation. One mass is positioned at the periphery of a shaft end rim such that upon failure of the stub shaft this mass is detached. Such displacement or detachment of the mass causes imbalance which creates vibration which in turn causes surge within a compressor associated with the stub shaft as well as possibly interference engagement with stable structure elements in order to limit turbine and/or compressor over speed.