COLLAPSIBLE STUB SHAFT OF A GAS TURBINE ENGINE

A controlled collapse stub shaft (29) is provided for allowing controlled axial movement of a mainline shaft which joins a fan or compressor to a turbine of a gas turbine engine. A first end (35) of the stub shaft is adapted to be joined to the mainline shaft. A second end (37) of the stub shaft is adapted to be joined to a part of the engine which is axially stationary relative to the controlled axial movement of the mainline shaft. The stub shaft (29) further has an annular body (33) between the first and second ends. The body contains a plurality of axially-spaced circumferential rows of circumferentially-extending slots (39), inter-slot ligaments (41) being formed between the slots of each row. Successive rows are offset. In this way, the ligaments of the axially forwardmost and rearwardmost rows excepted, each ligament is sandwiched between a forward slot and a rearward slot of its neighbouring rows. Further, each ligament is joined to adjacent ligaments of its neighbouring rows by circumferentially-extending bars (43) having a thickness in the axial direction corresponding to the axial spacing between the rows. The bars are axially deflectable to allow the axial distance between the first and second ends of the stub shaft to decrease.