Anti-windmilling system for a gas turbine engine

1. A method for preventing rotation of a fan in a gas turbine engine comprising:

driving a fan with a geared architecture that is driven by at least one shaft from a turbine section;

using one or more sensors to identify a non-operational engine condition comprising at least a windmilling condition;

including a control which receives data from the one or more sensors to determine if the aircraft is on the ground and is experiencing the windmilling condition by

determining weight on wheels,

determining if engine shut-down has been completed, and/or

determining aircraft velocity to identify if the gas turbine engine is stationary; and

activating an actuator positioned aft of the turbine section to prevent rotation of the fan during the windmilling condition.

2. The method of claim 1 , including activating the actuator to frictionally and/or magnetically restrain the at least one shaft from rotating to prevent the fan from windmilling.

3. The method of claim 1 , wherein the actuator includes a first feature and the at least one shaft includes a second feature that locks with the first feature when the actuator is activated to prevent the at least one shaft from rotating, wherein one of the first and second features comprises a dog extension and wherein the other of the first and second features comprises a recess that receives the dog extension, and including selectively activating the actuator to lock the first and second features together to prevent the fan from windmilling.

4. The method of claim 1 , including communicating data from the one or more sensors to a control and only activating the actuator when the control determines that the gas turbine engine is powered off and is stationary.