Abstract: A fuel injector for a gas turbine engine includes a support member and a nozzle tip disposed on the support member with a deformable, removable metallic or non-metallic seal member disposed between facing sealing surfaces of the support member and a shroud member of the nozzle tip. The deformable seal member includes one or more fuel passages through which fuel in one or more fuel circuits flows with the seal member sealingly separating the first and second fuel circuits and preventing external fuel leakage from the nozzle tip. The nozzle tip can include an inner fuel swirler that includes one or more swirler slots wherein each slot is so angled in an axial direction toward the discharge orifice of the nozzle tip assembly that operation of the nozzle tip assembly is unaffected by changes in fuel viscosity.