A disc for a rotor assembly of a gas turbine engine, the disc comprising: a disc hub (203; 403; 603); a disc web (202; 602) that extends radially outward from the disc hub, relative to an axis of rotation of the gas turbine engine; and a cover plate (206; 406; 506; 660) extending radially along an outside surface of the disc web toward the disc hub to create a cavity between the cover plate and disc web; wherein the disc comprises: an interstage coupling (207; 307; 407; 607) disposed on an axially extending surface (212; 312; 412; 612) at a peripheral aft edge of the disc hub, the interstage coupling including a protrusion that extends axially aft beyond an aft surface of the disc hub; a groove (233; 333; 533; 633) formed on the axially extending surface (212; 312; 412; 612) of the disc hub and located adjacent to the interstage coupling (207; 307; 407; 607), the groove including a forward surface (213; 313; 413; 513; 613) that extends radially into the disc hub to a groove floor (214; 314; 414; 514; 614) to define a groove depth, the groove floor extending axially to a groove aft surface (216; 316; 416; 516; 616), the groove aft surface extending radially outward to an axially extending surface of the disc hub; and a retaining ring (210; 310; 510; 610) configured to engage with the groove (233; 333; 533; 633) between the cover plate (206; 406; 506; 660) and disc, the retaining ring connecting to the interstage coupling (207; 307; 407; 607) of the disc hub (203; 403; 603) and extending into the groove, and the retaining ring being configured to retain the cover plate in place with respect to the disc, and wherein the retaining ring (210; 310; 510; 610) is configured to expand into the groove depth when a compressing force is applied between the cover plate (206; 406; 506; 660) and the disc. a disc hub (203; 403; 603); a disc web (202; 602) that extends radially outward from the disc hub, relative to an axis of rotation of the gas turbine engine; and a cover plate (206; 406; 506; 660) extending radially along an outside surface of the disc web toward the disc hub to create a cavity between the cover plate and disc web; wherein the disc comprises: an interstage coupling (207; 307; 407; 607) disposed on an axially extending surface (212; 312; 412; 612) at a peripheral aft edge of the disc hub, the interstage coupling including a protrusion that extends axially aft beyond an aft surface of the disc hub; a groove (233; 333; 533; 633) formed on the axially extending surface (212; 312; 412; 612) of the disc hub and located adjacent to the interstage coupling (207; 307; 407; 607), the groove including a forward surface (213; 313; 413; 513; 613) that extends radially into the disc hub to a groove floor (214; 314; 414; 514; 614) to define a groove depth, the groove floor extending axially to a groove aft surface (216; 316; 416; 516; 616), the groove aft surface extending radially outward to an axially extending surface of the disc hub; and a retaining ring (210; 310; 510; 610) configured to engage with the groove (233; 333; 533; 633) between the cover plate (206; 406; 506; 660) and disc, the retaining ring connecting to the interstage coupling (207; 307; 407; 607) of the disc hub (203; 403; 603) and extending into the groove, and the retaining ring being configured to retain the cover plate in place with respect to the disc, and wherein the retaining ring (210; 310; 510; 610) is configured to expand into the groove depth when a compressing force is applied between the cover plate (206; 406; 506; 660) and the disc. an interstage coupling (207; 307; 407; 607) disposed on an axially extending surface (212; 312; 412; 612) at a peripheral aft edge of the disc hub, the interstage coupling including a protrusion that extends axially aft beyond an aft surface of the disc hub; a groove (233; 333; 533; 633) formed on the axially extending surface (212; 312; 412; 612) of the disc hub and located adjacent to the interstage coupling (207; 307; 407; 607), the groove including a forward surface (213; 313; 413; 513; 613) that extends radially into the disc hub to a groove floor (214; 314; 414; 514; 614) to define a groove depth, the groove floor extending axially to a groove aft surface (216; 316; 416; 516; 616), the groove aft surface extending radially outward to an axially extending surface of the disc hub; and a retaining ring (210; 310; 510; 610) configured to engage with the groove (233; 333; 533; 633) between the cover plate (206; 406; 506; 660) and disc, the retaining ring connecting to the interstage coupling (207; 307; 407; 607) of the disc hub (203; 403; 603) and extending into the groove, and the retaining ring being configured to retain the cover plate in place with respect to the disc, and wherein the retaining ring (210; 310; 510; 610) is configured to expand into the groove depth when a compressing force is applied between the cover plate (206; 406; 506; 660) and the disc.