A cooling system for a turbine airfoil of a turbine engine having an inflow mid-chord feed channel and a trailing edge feed channel that are separated by an equalizer rib having a plurality of supply holes. The supply holes enable cooling fluids to be supplied to the trailing edge from the mid-chord feed channel to satisfy the cooling requirements of the entire trailing edge, which is greater than the mid-chord region. A crossover hole may be positioned in the equalizer rib at the tip section to enable the cooling fluids to pass between the mid-chord feed channel and a trailing edge feed channel. The crossover hole may enable cooling fluids to pass from the trailing edge feed channel into the mid-chord feed channel along the tip section to reduce stagnation in the outboard turn of the mid-chord serpentine channel.