Abstract: The endcover assembly for a combustor includes an endcover having an aperture, an insert disposed in the stepped bore opening through an internal face of the endcover, a fuel cartridge extending through the insert and aperture and a seal cover on the external face of the endcover. Seal cover/endcover annular seals are disposed in registering axial cavities to seal against fluid leakage externally of the endcover assembly. Generally C-shaped and W-shaped seals are disposed in the cavities between the stepped shoulders of the insert and aperture to seal against leakage through the internal face of the endcover. The seals maintain sealing engagement during assembly and thermal distortion during turbine usage.