Hydrodynamic intershaft seal and assembly

A seal assembly for providing a seal between an outer shaft and an inner shaft, the seal assembly comprising:

• an inner shaft;
• an outer shaft;
• and
• a seal subassembly disposed between the inner shaft and the outer shaft, the seal subassembly including:
• a split carbon ring radially split into a plurality of segments and having a plurality of splits between ends of adjacent segments, the segments including a circumferential inner radius and a sealing dam on the circumferential inner radius;
• a solid outer ring including a sealing face and a plurality of hydrodynamic grooves provided on a radial face;
• and
• a radial spring mechanism provided between a portion of the split carbon ring and a portion of the solid outer ring;
• wherein the spring mechanism is configured to engage a portion of an outer diameter of the split carbon ring and a portion of an inner diameter of the solid outer ring;
• and the spring mechanism is configured to urge the split carbon ring radially towards the inner shaft.