A propulsion system, comprising: a pylon ; and an inner fixed structure hingeably coupled to the pylon ; characterised by a magnetic fire seal coupled to the inner fixed structure , wherein the magnetic fire seal comprises: an exterior surface configured to form a sealing interface with the pylon ; an interior surface opposite the exterior surface ; a fire-resistant material surrounded by the exterior surface and the interior surface ; and a magnet located between the interior surface and the exterior surface and proximate the sealing interface ; wherein the inner fixed structure defines, at least, a portion of a core engine compartment , and wherein the magnetic fire seal provides sealing between the core engine compartment and an area exterior to the core engine compartment ; and wherein the magnetic fire seal is configured such that, when the magnetic fire seal is in an equilibrium position, wherein the seal is in neither a compressed nor stretched state, an exterior height (H2) of the magnetic fire seal is less than a deflection distance (D3) between the pylon and the inner fixed structure , the deflection distance (D3) between the pylon and the inner fixed structure being measured at pressure differential of 6.5 pounds per square inch (44.816 kPa) between the core engine compartment and the area exterior to the core engine compartment , the exterior height (H2) of the magnetic fire seal being measured at a tallest point on the exterior surface and in a direction perpendicular to the sealing interface . a pylon ; and an inner fixed structure hingeably coupled to the pylon ; characterised by a magnetic fire seal coupled to the inner fixed structure , wherein the magnetic fire seal comprises: an exterior surface configured to form a sealing interface with the pylon ; an interior surface opposite the exterior surface ; a fire-resistant material surrounded by the exterior surface and the interior surface ; and a magnet located between the interior surface and the exterior surface and proximate the sealing interface ; an exterior surface configured to form a sealing interface with the pylon ; an interior surface opposite the exterior surface ; a fire-resistant material surrounded by the exterior surface and the interior surface ; and a magnet located between the interior surface and the exterior surface and proximate the sealing interface ; wherein the inner fixed structure defines, at least, a portion of a core engine compartment , and wherein the magnetic fire seal provides sealing between the core engine compartment and an area exterior to the core engine compartment ; and wherein the magnetic fire seal is configured such that, when the magnetic fire seal is in an equilibrium position, wherein the seal is in neither a compressed nor stretched state, an exterior height (H2) of the magnetic fire seal is less than a deflection distance (D3) between the pylon and the inner fixed structure , the deflection distance (D3) between the pylon and the inner fixed structure being measured at pressure differential of 6.5 pounds per square inch (44.816 kPa) between the core engine compartment and the area exterior to the core engine compartment , the exterior height (H2) of the magnetic fire seal being measured at a tallest point on the exterior surface and in a direction perpendicular to the sealing interface . <EOS>