Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

Abstract: A method of managing a gas turbine engine variable area fan nozzle includes the steps of operating a variable area fan nozzle according to a first operating schedule. An icing condition input is evaluated to determine the likelihood of ice presence. The first operating schedule is altered to provide a variable area fan nozzle position if ice is likely present or actually present to provide an icing operating schedule different than the first operating schedule. The first operating schedule corresponds to the flaps at least partially open at air speeds below a first airspeed. The altering step includes closing the flaps below the first airspeed as part of the icing operating schedule. The variable area fan nozzle position is adjusted according to the icing operating schedule. A fan is arranged in a fan nacelle that includes a flap configured to be movable between first and second positions. An actuator is operatively coupled to the flap.

Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

Abstract: A method of managing a gas turbine engine variable area fan nozzle includes the steps of operating a variable area fan nozzle according to a first operating schedule. An icing condition input is evaluated to determine the likelihood of ice presence. The first operating schedule is altered to provide a variable area fan nozzle position if ice is likely present or actually present to provide an icing operating schedule different than the first operating schedule. The first operating schedule corresponds to the flaps at least partially open at air speeds below a first airspeed. The altering step includes closing the flaps below the first airspeed as part of the icing operating schedule. The variable area fan nozzle position is adjusted according to the icing operating schedule. A fan is arranged in a fan nacelle that includes a flap configured to be movable between first and second positions. An actuator is operatively coupled to the flap.

Abstract: A method of managing a gas turbine engine variable area fan nozzle includes the steps of evaluating an icing condition to determine the likelihood of ice presence. A variable area fan nozzle position is altered if ice is likely present or actually present. The gas turbine engine includes a fan nacelle including a flap configured to be moveable between first and second positions. An actuator is operatively coupled to the flap. A controller is configured to evaluate an icing condition to determine the likelihood of ice presence. The controller is configured to alter a variable area fan nozzle position schedule if ice is likely present by providing a command to the actuator to adjust the flap from the first position to the second position.

Abstract: A turbofan engine control system for managing a low pressure turbine speed is provided. The turbofan engine control system includes a low spool having a low pressure turbine that are housed in a core nacelle. The low pressure turbine is adapted to rotate at a speed and includes a maximum design speed. A turbofan is coupled to the low spool. A fan nacelle surrounds the turbofan and core nacelle and provides a bypass flow path. The bypass flow path includes a nozzle exit area. A controller is programmed to command a flow control device adapted to effectively decrease the nozzle exit area in response to a condition. Reducing the nozzle exit area, either physically or otherwise, maintains the speed below the maximum design speed.

Abstract: A method of managing a gas turbine engine includes the steps of detecting an airspeed and detecting a fan speed. A parameter relationship is referenced related to a desired variable area fan nozzle position based upon at least airspeed and fan speed. The detected airspeed and detected fan speed is compared to the parameter relationship to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted in response to the determination of the target area fan nozzle position and at least one threshold.

Abstract: A method of managing a gas turbine engine operating line includes detecting an air speed and a fan speed. A data table is referenced that includes a desired variable area fan nozzle position based upon air speed and fan speed. The detected air speed and detected fan speed are compared to the data table to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted to the target variable area fan nozzle position.

Abstract: A turbofan engine control system is provided for managing a low pressure compressor operating line. The engine includes a low spool having a low pressure compressor housed in a core nacelle. A turbofan is coupled to the low spool. A fan nacelle surrounds the turbofan and core nacelle and provides a bypass flow path having a nozzle exit area. A controller is programmed to effectively change the nozzle exit area in response to an undesired low pressure compressor stability margin which can result in a stall or surge condition. In one example, the physical nozzle exit area is decreased at the undesired stability condition occurring during engine deceleration. A low pressure compressor pressure ratio, low spool speed and throttle position are monitored to determine the undesired stability margin.

Abstract: A method of managing a gas turbine engine variable area fan nozzle includes the steps of evaluating an icing condition to determine the likelihood of ice presence. A variable area fan nozzle position is altered if ice is likely present or actually present. The gas turbine engine includes a fan nacelle including a flap configured to be moveable between first and second positions. An actuator is operatively coupled to the flap. A controller is configured to evaluate an icing condition to determine the likelihood of ice presence. The controller is configured to alter a variable area fan nozzle position schedule if ice is likely present by providing a command to the actuator to adjust the flap from the first position to the second position.

Abstract: A method of managing a gas turbine engine operating line includes detecting an air speed and a fan speed. A data table is referenced that includes a desired variable area fan nozzle position based upon air speed and fan speed. The detected air speed and detected fan speed are compared to the data table to determine a target variable area fan nozzle position. An actual variable area fan nozzle position is adjusted to the target variable area fan nozzle position.

Abstract: (A1) A turbofan engine (10) is provided that includes a spool (14). The spool (14) supports a turbine (18) and is housed within a core nacelle (12). A fan (20) is coupled to the spool (14) and includes a target operability line. The target operability line provides desired fuel consumption, engine performance, and/or fan operability margin. A fan nacelle (34) surrounds the fan (20) and core nacelle (12) to provide a bypass flow path (39) having a nozzle exit area (40). A controller (50) is programmed to command a flow control device (41) for changing the nozzle exit area (40). The change in nozzle exit area (40) achieves the target operability line in response to an engine operating condition that is a function of airspeed and throttle position. A change in the nozzle exit area (40) is used to move the operating line toward a fan stall or flutter boundary by manipulating the fan pressure ratio.

Abstract: A turbofan engine is provided that includes a fan nacelle surrounding a core nacelle. The core nacelle houses a spool. The fan and core nacelles provide a bypass flow path having a nozzle exit area. A turbofan is arranged within the fan nacelle upstream from the core nacelle. A flow control device is adapted to effectively change the nozzle exit area to obtain a desired operating condition for the turbofan engine. A gear train couples the spool and turbofan for reducing a turbofan rotational speed relative to a spool rotational speed. A controller is programmed to respond to at least one sensor. The controller is programmed to effectively control the nozzle area.

Abstract: A turbofan engine control system is provided for managing a low pressure compressor operating line. The engine includes a low spool having a low pressure compressor housed in a core nacelle. A turbofan is coupled to the low spool. A fan nacelle surrounds the turbofan and core nacelle and provides a bypass flow path having a nozzle exit area. A controller is programmed to effectively change the nozzle exit area in response to an undesired low pressure compressor stability margin which can result in a stall or surge condition. In one example, the physical nozzle exit area is decreased at the undesired stability condition occurring during engine deceleration. A low pressure compressor pressure ratio, low spool speed and throttle position are monitored to determine the undesired stability margin.

Abstract: (A1) A turbofan engine (10) is provided that includes a spool (14). The spool (14) supports a turbine (18) and is housed within a core nacelle (12). A fan (20) is coupled to the spool (14) and includes a target operability line. The target operability line provides desired fuel consumption, engine performance, and/or fan operability margin. A fan nacelle (34) surrounds the fan (20) and core nacelle (12) to provide a bypass flow path (39) having a nozzle exit area (40). A controller (50) is programmed to command a flow control device (41) for changing the nozzle exit area (40). The change in nozzle exit area (40) achieves the target operability line in response to an engine operating condition that is a function of airspeed and throttle position. A change in the nozzle exit area (40) is used to move the operating line toward a fan stall or flutter boundary by manipulating the fan pressure ratio.

Abstract: (A2) A turbofan engine control system for managing a low pressure turbine speed is provided. The turbofan engine control system includes a low spool having a low pressure turbine that are housed in a core nacelle. The low pressure turbine is adapted to rotate at a speed and includes a maximum design speed. A turbofan is coupled to the low spool. A fan nacelle surrounds the turbofan and core nacelle and provides a bypass flow path. The bypass flow path includes a nozzle exit area. A controller is programmed to command a flow control device adapted to effectively decrease the nozzle exit area in response to a condition. Reducing the nozzle exit area, either physically or otherwise, maintains the speed below the maximum design speed.