Flammability Reduction System is far superior than a Fuel Tank inerting system. It is based on the principle that lean fuel air mixtures do not ignite. The fuel air mixture can be rendered lean by several methods. Cooling the ullage mixture outside the fuel tank to condense out fuel vapors is a very simple method. The condensed fuel is returned back to the fuel tank and the chilled ullage mixture is returned back to the fuel tank. The cooling can be done by an inexpensive air cooler. Cold ambient air in flight helps maintain the fuel tank non-flammable. The fuel burn penalty of the system is low, the weight is low and it is safer than a nitrogen system. No vent system modification is necessary and the system does not exhaust out hydrocarbon vapors that may be carciogenic. Suggest you read about it on SAE web site, "Method and system for making a fuel tank inert without an inert gas."