A method and systems for controlling an engine are provided. The system includes an engine model programmed to receive engine operating condition values from a plurality of sensors on an engine. The engine model is programmed to determine a plurality of engine operating parameter values. The system also includes a processor configured to compare the operating parameter values to a predetermined allowable range for the operating parameter and control the operation of the engine to facilitate returning the determined operating parameter to the allowable range or maintaining the determined operating parameter within the allowable range, output the determined operating parameter values to a user, and/or generate maintenance requests based on the comparison.