The ducted fan (12) of a ducted fan gas turbine engine (10) is surrounded by a compartment (26), which is packed with bristles (38). Should a blade of the fan stage (12) disintegrate during operation of engine (10), the resulting fragments, if they pass through an abradeable honeycomb structure (32), will collide with the bristles (38), which will absorb the energy exerted by the fragments, and thus prevent puncturing of the outer wall (18) of the fan duct structure.