Aircraft engine control system for maintaining constant thrust below sea level

A method of controlling an aircraft engine with an engine control system to maintain a prescribed engine thrust at a value corresponding to operation at sea level independent of a current altitude of an aircraft comprising:

• determining a reference thrust corresponding to a value of a thrust setting parameter at sea level for a current air speed according to a predefined relationship in response to operation at an altitude below sea level;
• calculating an adjustment factor based on a relationship between a current altitude and sea level;
• determining the prescribed engine thrust at the current altitude by applying the calculated adjustment factor to the reference thrust;
• determining the value of the thrust setting parameter that provides the prescribed engine thrust at sea level according to a predefined relationship of the reference thrust and the current airspeed;
• and
• operating the aircraft engine based on the determined value of the thrust setting parameter to provide the prescribed engine thrust.

A control system for an aircraft engine comprising:

• a controller including a processor and a memory for storing engine operating settings indicative of a prescribed thrust based on a thrust setting parameter and an aircraft operating condition, wherein the controller is programmed:
• to receive information indicative of the thrust setting parameter and the aircraft operating condition from at least one sensor associated with an aircraft engine;
• to set the prescribed thrust at a selected aircraft operating parameter independent of a thrust setting model by determining a reference thrust corresponding to a value of the thrust setting parameter at the selected aircraft operating parameter for a current aircraft operating parameter according to a predefined relationship in response to operation at a threshold aircraft operating condition, calculating an adjustment factor based on a difference between a current aircraft operating parameter and the selected aircraft operating parameter, determining the prescribed thrust at the current aircraft operating parameter by applying the calculated adjustment factor to the reference thrust, and determining a value of the thrust setting parameter that provides the prescribed thrust at the current aircraft operating parameter according to a predefined relationship of the reference thrust and a current airspeed;
• and
• to operate the aircraft engine based on the determined value of the thrust setting parameter to provide the prescribed thrust.