The main building block of an engine is a so-called spool. This is a combination of a turbine, a shaft, a compressor and potentially a fan, all rotating at the same speed. A very common configuration is what we call a dual spool engine. The low speed spool here consists of the fan, the low-pressure compressor, the fan shaft and the low pressure turbine, while the high speed spool consists of the rest of the components (high pressure compressor, core shaft and high pressure turbine). The task of the compressors is to increase the pressure of the air required by the engine, while in the combustion chamber the air is combined with fuel and the mixture is burned. The released energy is subsequently captured by the turbines which, in turn, drive the rotation of the compressors and the fan. The fan is a very important part of a turbofan engine, since it is what generates the biggest amount of thrust, serving to propel the aircraft. In a high-bypass turbofan engine two different paths for the air exist, one called the core path, going through the compressors and turbines, and the other called the bypass path (going through just the fan). It is the air in the bypass path that generates the amount of thrust required to move the aircraft in a commercial transportation setting, which is what gives this type of engine its "high-bypass" characterization. In military aircraft that move in supersonic speeds, on the other hand, it is more fuel efficient to have little bypass air flow, or even none at all.

In all modern turbofan engines there is a so called FADEC system (Full Authority Digital Engine Control), which monitors and controls everything about the engine, including thrust control, fuel control, power management, health monitoring of the engine, thrust reverser control, and so on. Due to this great amount of responsibility, a FADEC is typically designed with a high level of redundancy, in order to be fault tolerant. For example, it contains two or more identical computers, which are coordinated by monitoring software that detects failures in the FADEC itself and decides which computer should be in charge.

The system for UC5 is an aircraft engine model along with a corresponding controller set. In particular, the engine model is represented by a linear state space model of 18 internal states, 4 outputs, and 3 inputs. Two sets of controllers have been designed, one for thrust control and another for low-pressure compressor spool speed control, along with switching logic that activates the appropriate controller set based on the engine state and pilot commands.

Safety and performance of the engine-controller pair will be evaluated under various types of faults (e.g. sensor faults, engine mechanical failures, abrupt changes in operating environment, etc). In particular, we will analyze, under the presence of such faults, the ability of the controller to (a) respond fast / smoothly to pilot input, (b) maintain engine operation within acceptable limits (e.g. max fan / compressor speed, etc), and (c) maintain steady state safe engine operation under no input change.