A gas turbine engine includes a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order; a fan defining a fan axis and comprising a plurality of fan blades rotatable about the fan axis; and a pitch change mechanism operable with the plurality of fan blades to control a pitch of the plurality of fan blades. The pitch change mechanism imparts a torque to each fan blade of the plurality of fan blades via first and second forces imparted in opposite directions to each fan blade of the plurality of fan blades.

An adaptive flight control system for controlling the pitch of blades of a propulsive propeller of a hybrid helicopter as a function of the return value of the pitch. The adaptive flight control system comprises control means supplying the pitch control order, a piloting member controlling variation of the pitch, and piloting means applying a control gain in order to transform the control order into a setpoint, and transmitting the setpoint to the piloting member. The piloting means include information return means applying a return gain that is variable to the return value of the variation of the pitch to the piloting means, also modifying the control gain as a function of the return value.

An adaptive flight control system for controlling the pitch of blades of a propulsive propeller of a hybrid helicopter as a function of the return value of the pitch. The adaptive flight control system comprises control means supplying the pitch control order, a piloting member controlling variation of the pitch, and piloting means applying a control gain in order to transform the control order into a setpoint, and transmitting the setpoint to the piloting member. The piloting means include information return means applying a return gain that is variable to the return value of the variation of the pitch to the piloting means, also modifying the control gain as a function of the return value.

A central-positioned pitch control device used in a coaxial helicopter includes an upper propeller hub; a lower propeller hub; a first blade mounted on the outside of the upper propeller hub; a second blade mounted on the outside of the lower propeller hub; and a central-positioned pitch control device placed between the upper propeller hub and the lower propeller hub.