This paper presents a solution to the problems of fuel tank fire protection by means of nitrogen inerting. Background relationships with the successful XB-70 inerting system, which led to the development of the commercial inerting system, are also discussed.
Specifically, this paper shows how aircraft inerting system design is influenced by the release of air from the fuel at high altitudes. Data are presented to show the likelihood of air saturated fuel, the way in which it is released from the fuel at high altitudes, and the effect of this release on the inert atmosphere in the fuel tanks. Problems created by this air release are discussed. Test data are presented on a scrubbing device that predictably provides controlled release and dilution of dissolved air from the fuel, thereby allowing the inert atmosphere to be maintained. Data are presented on the effect of this controlled air release on the fuel boost pump operation.
Additionally, the status of the current inerting system flight test program, as installed aboard a military aircraft, is presented.