Turbomachine casing assembly

A turbomachine casing assembly comprising:

• a first casing portion configured to at least partially encase one or more rotating aerofoil structures of a turbomachine;
• a second casing portion, the first casing portion being movable with respect to the second casing portion;
• and
• one or more resilient elements arranged so as to resist movement of the first casing portion with respect to the second casing portion, wherein
• the first casing portion is configured to move, from an initial position, in a substantially radial direction of the turbomachine casing assembly when contacted by the one or more rotating aerofoil structures,
• the first casing portion is configured to return toward the initial position when the contact by the one or more rotating aerofoil structures ceases,
• the first casing portion and the second casing portion are separated by a space, and
• an end of the first casing portion moves into the space between the first casing portion and the second casing portion when the first casing portion is contacted by the one or more rotating aerofoil structures,
• wherein the first casing portion is rotatably coupled with respect to the second casing portion at a second end of the first casing portion.