Abstract: 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.

Abstract: A gas turbine engine 10 includes an intermediate pressure compressor 14 connected to an intermediate pressure turbine 22 by a driveshaft 28. The driveshaft 28 comprises a downstream turbine shaft 34 attached to the intermediate pressure turbine 22 and an upstream compressor shaft 32 attached to the intermediate pressure compressor 14. The compressor shaft 32 and turbine shaft 34 are connected together by a splined connection 36 which allows the turbine shaft 34 to drive the compressor shaft 32. If the splined connected 36 should fail, so that it no longer transmits torque, a further splined connection 41 comes into operation to transmit torque between the turbine shaft 34 and compressor shaft 32. When this happens, torque is transmitted via a torsionally weakened, shear section 48 of the turbine shaft 34 which tends to break under certain engine conditions. The turbine shaft 34 is then released axially and turbine overspeed is restrained.