An outer shroud of an intermediate casing for a dual flow turbine engine for an aircraft, the shroud including: an annular downstream portion provided with a shroud opening passing through an annular downstream edge of the shroud; a connecting member (50) attached to the annular downstream portion, and intended to attach an arm that passes through a secondary flow path; an air-sealing and fire-resistance device including: a portion including: a pad arranged in a hollow annular area of the annular downstream edge of the shroud; a blade protruding from the pad and clamped between a circumferential end and the radially outer end of the arm, a leaf spring (pressing the pad into the hollow annular area.