The invention relates to an exhaust casing for a turbine engine of an aircraft, including: a collar (4), a hub (5), hollow arms (63) connecting said collar (4) to said hub (5), and an opening piece (3) which is located on the collar (4) and is suitable for being connected to an outlet tube (30) of a transient-operation valve of the turbine engine. In said exhaust casing, said opening piece (3) is attached onto the collar (4) and forms an extension of a hollow arm (63) such that an air flow (7) leaving the outlet tube (30) of the transient-operation valve penetrates the hollow arm (63) and flows into the hub (5).