Active fan flutter control system and method

A flutter control system (10) for a turbomachine fan includes a plurality of fan case sensors (12;38) located at a fan case of the turbomachine and configured to sense passing of blade tips of a fan of the turbomachine. A controller (30) is operably connected to the plurality of fan case sensors (12;38). A variable fan area nozzle actuator (32) is operably connected to the controller (30), such that the variable fan area nozzle actuator (32) urges a change in fan nozzle area (30) in response to data from the plurality of fan case sensors (12;38) indicating flutter or near flutter conditions. A method of flutter control for a turbomachine fan includes sensing a blade tip passing of a plurality of fan blades (18). Data from a plurality of fan case sensors (12;38) are compared to a threshold and a fan exit area (36) is changed based on the comparison to dampen flutter of the plurality of fan blades.