Traditional design methods for aircraft turbine engine control systems have relied on the use of linearized models and linear control theory. While these controllers can provide satisfactory performance, they do not exploit all the available knowledge about the nonlinear engine dynamics. Recent advances in computer-aided nonlinear control system design technology have made it feasible to design control systems using a detailed model of the engine. These nonlinear engine control systems have the potential to deliver a more precise control of the engine dynamics while satisfying multiple operational requirements. Using a NASA-supplied engine model, Phase I research will develop a nonlinear engine control system that can deliver uniform performance over the entire operating region. Operation at multiple operating points and transitions between them will be demonstrated during the Phase I research. Phase II work will develop a rapid-prototyping design environment for nonlinear engine control systems and real-time controller code generation for implementing the nonlinear control on engine control computer. Advanced engine control concepts such as active clearance control and adaptive engine control will also be demonstrated during the Phase II work. The design software and the control technology developed under the present SBIR will be commercialized during the Phase III research.