Seal assembly with anti-rotation feature

A bleed-off valve for an aircraft gas turbine engine, the bleed-off valve comprising:

• a housing extending circumferentially about a centerline axis of the bleed-off valve;
• a piston disposed within the housing, the piston configured to translate along the centerline axis, the piston including a piston body forming an annular seal groove;
• and
• a piston seal assembly comprising:
• a ring including a ring body, the ring body extending circumferentially about a centerline axis of the piston seal assembly, the ring body extending radially between and to an outer radial ring side and an inner radial ring side, the ring body extending circumferentially between and to a first circumferential ring end and a second circumferential ring end, the ring body forming a ring end gap of the ring between the first circumferential ring end and the second circumferential ring end, the first circumferential ring end extending from the outer radial ring side and the inner radial ring side, and the second circumferential ring end extending from the outer radial ring side and the inner radial ring side;
• and
• a seal including a seal body, the seal body extending circumferentially about the centerline axis, the seal body extending radially between and to an outer radial seal side and an inner radial seal side, the seal body radially circumscribing the ring body with the inner radial seal side disposed on the outer radial ring side, the seal body extending circumferentially between and to a first circumferential seal end and a second circumferential seal end, the seal body forming a seal end gap of the seal between the first circumferential seal end and the second circumferential seal end, the first circumferential seal end extending from the outer radial seal side and the inner radial seal side, the second circumferential seal end extending from the outer radial seal side and the inner radial seal side, the seal body circumferentially continuously contacts the ring body from the first circumferential seal end to the first circumferential ring end, and the seal body circumferentially continuously contacts the ring body from the second circumferential seal end to the second circumferential ring end;
• the ring body and the seal body forming an anti-rotation feature of the piston seal assembly, the anti-rotation feature configured to limit relative circumferential movement between the ring body and the seal body;
• wherein the anti-rotation feature includes a protrusion extending radially outward from the outer radial ring side;
• wherein the ring end gap is circumferentially offset from the seal end gap by an offset angle Θ;
• wherein the ring end gap has a first circumferential position, the seal end gap has a second circumferential position, and the anti-rotation feature is configured to limit relative motion between the first circumferential position and the second circumferential position within a threshold rotation limit to provide a leakage characteristic of the piston seal assembly;
• and
• wherein the threshold rotation limit is within a range of two degrees (2°) and ten degrees (10°).