The goal of this program is to develop a miniaturized and in-situ operated gas microsensor array for the real time monitoring of chemical composition of turbine engine combustors and/or exhaust streams to improve NASA's aeronautical flight test capabilities. Phase II will develop a high temperature microsensor array suitable for incorporation in engines, as installed in aircraft. Sensor arrays developed by our team and research partners have been demonstrated for ground test usage to quantify composition of critical constituents in turbine engine exhaust products, e.g., CO, CO2, NOx, O2 and HC. To date, our research efforts for exhaust monitoring have focused on ground applications, such as installations in stationary rigs for engine development. The goal of the proposed program is to build on knowledge accumulated on ground-based systems to develop a flyable prototype. The program will leverage test opportunities in larger research programs to move through the maturation steps from ground-based to flyable systems. The microsensor array probe, cabling and control electronics will be developed to withstand the harsh environment of an aircraft engine. Initial tests will be performed with the prototype installed the engine of a grounded airplane. Beyond Phase II, full flight tests are envisioned.