Fan containment system

A fan containment system arranged to be fitted around an array of radially extending fan blades mounted on a hub in an axial gas turbine engine, each fan blade having a respective fan blade tip, the fan containment system comprising:

• a generally cylindrical fan case including a hook, the hook projecting in a generally radially inward direction and positioned axially forward of the radial array of fan blades when the fan containment system is fitted around the radial array of fan blades;
• a fan track liner disposed on the radially inner surface of the fan case;
• and
• a damaging tool which projects radially inwards from the fan case towards the fan blade tips when the fan containment system is fitted around the array of radially extending fan blades, the damaging tool having a tip which is radially outward of the fan blade tips during normal operation of the gas turbine engine,
• wherein the damaging tool is configured such that in the event that, during operation of the gas turbine engine, one of the fan blades is released from the hub, the tip of the damaging tool damages the fan blade tip of the released fan blade so as to promote penetration of the fan blade into the fan track liner and ensure the fan blade collides with the hook.