A fan containment system for fitment around an array of radially extending fan blades mounted on a hub in an axial gas turbine engine. The fan containment system comprises a fan case having an annular casing element for encircling an array of fan blades and a hook projecting in a generally radially inward direction from the annular casing element. The fan containment system further includes an annular fan track liner comprising a plurality of adjacent arcuate fan track liner panels. Each of the plurality of fan track liner panels is connected to the fan case at the hook via one or more fasteners configured to permit movement of the fan track liner panel relative to the hook such that the fan track liner panel can pivot towards the annular casing element when a released fan blade impacts the fan track liner panel.