System for Measuring and Reporting Aircraft Ullage Oxygen

ABSTRACT: Physical Sciences Inc. (PSI) proposes to develop, test, and demonstrate a sensor system for measuring and reporting in real-time the oxygen concentration in the fuel tank ullage of advanced tactical aircraft such as the F-35 Joint Strike Fighter. The O2 sensor system is intended to support the Onboard Inert Gas Generation System (OBIGGS) aircraft fuel tank inerting systems. OBIGGS protects fuel tanks of military and civilian aircraft from explosion by supplying to the ullage Nitrogen-Enriched-Air (NEA) that reduces the fractional O2 content. If the fuel system is not effectively inerted then the overall mission effectiveness is degraded. When fully-developed in Phases II and III, the sensor system will also report fuel tank pressure and fuel temperature. In Phase I, PSI will adapt its laser-based oxygen sensor developed previously for measuring ullage O2 in transport aircraft to meet the challenging F-35 requirements. Phase I will culminate with performance testing in simulated flight environments and conditions. BENEFIT: The real-time O2 sensor resulting from the proposed R & D will: a) improve aircraft safety by providing continual pilot awareness of fuel tank inerting status; b) enable closed-loop feedback control of NEA thereby enhancing efficient use of engine bleed air for cooling aircraft systems, c) increase the mission readiness rate and reduce flight preparation costs by informing ground crews when inerting service is needed or not; and d) provide early indications of maintenance requirements or OBIGGS system malfunction. An oxygen sensor system meeting Air Force specifications will be the first product resulting from this project. A similar product will also serve: a) the civilian aviation market, where inerting systems are now required to be installed in several new construction civilian aircraft, ranging from jumbo to regional jets, and retrofitted to much of the existing airliner fleet; and b) non-aviation markets where oxygen is monitored to preclude explosion of fuel and other hydrocarbon storage tanks. Within military aviation, it is estimated that at least 2000 sensor units will be needed. Markets of similar size are likely for non-aviation applications.