Complex sentence: Full-flow staged combustion (FFSC) is a variation on the staged combustion cycle where all of the fuel and all of the oxidizer pass through their respective power turbines, except a small amount of each swapped and combusted to supply power for the turbines.
Split into simpler sentences: Full-flow staged combustion (FFSC) is a variation on the staged combustion cycle where all of the fuel and all of the oxidizer pass through their respective power turbines. A small amount of fuel and oxidizer is swapped and combusted to supply power for the turbines.