A turbomachine casing assembly (100,200,300), comprising: a first casing element (110,210,310) located radially outward of one or more rotating aerofoil elements of a turbomachine; a second casing element (120,220,320) located radially outward of the first casing element (110,210,310); and a void, provided between the first casing element (110,210,310) and the second casing element, at a first end of the first casing element (110,210,310), a radially distal face (116,216,316) of the first casing element (110,210,310) being angled relative to a radially proximal face (124,224,324) of the second casing element (120,220,320), such that the void is provided therebetween; wherein the first end of the first casing element (110,210,310) is located against a corresponding first end of the second casing element (120,220,320) by an energy absorbing element, and the first casing element (110,210,310) comprises a cantilever, the cantilever being arranged in a region extending along the first casing element (110,210,310) from the first end and having a pivot axis at a mid portion of the first casing element (110,210,310); whereby upon release of one of the rotating aerofoil elements, the cantilever bends into the void provided between the first and second casing elements(110,210,310: 120,220,320), which causes the energy absorbing element to deform and to thereby absorb at least some of the impact energy resulting from the released rotating aerofoil element, characterised in that the radially distal face (116,216,316) of the first casing element (110,210,310) comprises a slit, the slit being disposed along the pivot axis on the radially distal face (116,216,316) of the first casing element (110,210,310) and extending substantially through a core of the first casing element (110,210,310). a first casing element (110,210,310) located radially outward of one or more rotating aerofoil elements of a turbomachine; a second casing element (120,220,320) located radially outward of the first casing element (110,210,310); and a void, provided between the first casing element (110,210,310) and the second casing element, at a first end of the first casing element (110,210,310), a radially distal face (116,216,316) of the first casing element (110,210,310) being angled relative to a radially proximal face (124,224,324) of the second casing element (120,220,320), such that the void is provided therebetween; wherein the first end of the first casing element (110,210,310) is located against a corresponding first end of the second casing element (120,220,320) by an energy absorbing element, and the first casing element (110,210,310) comprises a cantilever, the cantilever being arranged in a region extending along the first casing element (110,210,310) from the first end and having a pivot axis at a mid portion of the first casing element (110,210,310); whereby upon release of one of the rotating aerofoil elements, the cantilever bends into the void provided between the first and second casing elements(110,210,310: 120,220,320), which causes the energy absorbing element to deform and to thereby absorb at least some of the impact energy resulting from the released rotating aerofoil element, characterised in that the radially distal face (116,216,316) of the first casing element (110,210,310) comprises a slit, the slit being disposed along the pivot axis on the radially distal face (116,216,316) of the first casing element (110,210,310) and extending substantially through a core of the first casing element (110,210,310).