Abstract: A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a low pressure turbine, driving a high pressure compressor with a high pressure turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

Abstract: A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a low pressure turbine, driving a high pressure compressor with a high pressure turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

Abstract: A gas turbine engine includes a fan section that has a fan. A fan casing surrounds the fan section. A compressor section defines an engine axis. A gear train reduces a rotational speed of the fan relative to a shaft. A low pressure turbine is coupled to the shaft. A nacelle extends along the engine axis and surrounds the fan casing, a bypass ratio of greater than 10. A variable area fan nozzle defines a discharge airflow area. A flutter sensing system includes a controller programmed to move the variable area fan nozzle to vary the discharge airflow area in response to detecting an airfoil flutter condition associated with adjacent airfoils of the fan.

Abstract: A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a first turbine, driving a compressor with a second turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, and having a bypass ratio of greater than 10, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

Abstract: A gas turbine engine includes a fan section that has a fan with a plurality of airfoils, a compressor section, a gear train that reduces a rotational speed of the fan relative to a shaft in operation, a turbine section that has a first turbine and a second turbine, and a bypass ratio of greater than 10. The first turbine drives the shaft. A nacelle extends along an engine axis and surrounds the fan. A variable area fan nozzle defines a discharge airflow area. A fan airfoil flutter sensing system has a first sensor that actively and selectively detects a fan airfoil flutter condition in operation, and communicates with a controller programmed to move the variable area fan nozzle and vary the discharge airflow area to mitigate the flutter condition.

Abstract: A method of operation for a gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, reducing a rotational speed of a fan relative to a shaft through a gear train, driving the shaft with a first turbine, driving a compressor with a second turbine, communicating airflow from the fan through a bypass passage defined by a nacelle, the nacelle extending along an engine axis and surrounding the fan, and having a bypass ratio of greater than 10, discharging the airflow through a variable area fan nozzle defining a discharge airflow area, detecting an airfoil flutter condition associated with adjacent airfoils of the fan, and moving the variable area fan nozzle to vary the discharge airflow area and mitigate the airfoil flutter condition.

Abstract: A gas turbine engine includes a fan section that has a fan with a plurality of airfoils, a compressor section, a gear train that reduces a rotational speed of the fan relative to a shaft in operation, a turbine section that has a first turbine and a second turbine, and a bypass ratio of greater than 10. The first turbine drives the shaft. A nacelle extends along an engine axis and surrounds the fan. A variable area fan nozzle defines a discharge airflow area. A fan airfoil flutter sensing system has a first sensor that actively and selectively detects a fan airfoil flutter condition in operation, and communicates with a controller programmed to move the variable area fan nozzle and vary the discharge airflow area to mitigate the flutter condition.

Abstract: A gas turbine engine includes a fan section that has a fan. A fan casing surrounds the fan section. A compressor section defines an engine axis. A gear train reduces a rotational speed of the fan relative to a shaft. A low pressure turbine is coupled to the shaft. A nacelle extends along the engine axis and surrounds the fan casing, a bypass ratio of greater than 10. A variable area fan nozzle defines a discharge airflow area. A flutter sensing system includes a controller programmed to move the variable area fan nozzle to vary the discharge airflow area in response to detecting an airfoil flutter condition associated with adjacent airfoils of the fan.

Abstract: A system for diagnosing a rotating airfoil has an image capture device and a light emitting device. A control is programmed to actuate at least one of the image capture device and the light at a particular time to capture an image of a rotating airfoil being monitored, and then compare the captured image to an expected image. A method of diagnosing damage to a rotating airfoil is also disclosed.

Abstract: An exemplary gas turbine engine assembly includes a fan casing within a nacelle, a variable area fan nozzle. A controller is operable to move the variable area fan nozzle to influence a discharge airflow area associated with the variable area fan nozzle in response to an airfoil flutter condition. A gear train reduces a rotational speed of a fan in the gas turbine engine relative to another portion of the gas turbine engine.

Abstract: An exemplary gas turbine engine assembly includes a fan casing within a nacelle, a variable area fan nozzle. A controller is operable to move the variable area fan nozzle to influence a discharge airflow area associated with the variable area fan nozzle in response to an airfoil flutter condition. A gear train reduces a rotational speed of a fan in the gas turbine engine relative to another portion of the gas turbine engine.

Abstract: An exemplary gas turbine engine assembly includes a nacelle, a core engine casing within the nacelle, a low pressure turbine having a pressure ratio that is greater than five, and a bypass passage established between the nacelle and the core engine casing. About 80% or more of airflow entering the engine is moved through the bypass passage.

Abstract: A gas turbine engine system includes a nacelle, a fan casing within the nacelle, a variable area fan nozzle, a sensor and a controller. The sensor detects an airfoil flutter condition. The controller communicates with the sensor and is operable to move the variable area fan nozzle to influence a discharge airflow area in response to the detection of the airfoil flutter condition.