Fan containment system, corresponding fan assembly and gas turbine engine

A fan containment system (200) arranged to be fitted around an array of radially extending fan blades (40) which are mounted on a hub in an axial gas turbine engine. The fan containment system comprises: a generally cylindrical fan case (250) including a hook (260), the hook projecting in a generally radially inward direction and positioned axially forward of the radial array of fan blades; a fan track liner (252) disposed on the radially inner surface of the fan case; and a damaging tool (270) which projects radially inwards from the fan case towards the fan blade tips. The damaging tool is configured such that in the event that one of the fan blades is released from the hub, the tip of the damaging tool damages the tip of the fan blade and improves the penetration of the fan blade into the fan track liner. A corresponding fan assemby and gas turbine engine are also disclosed.