The present invention relates to primary flight controls (10) for main and/or tail rotors (4) of helicopters with an electro-mechanical interface between any of Fly-By-Wire and/or of Fly-by-light controls and hydraulic servo actuators (8) for control force amplification towards said main and/or tail rotor controls (4). For each of the main and/or tail rotor controls (4) there is provided but one of the hydraulic servo actuators (8), connected by one mechanical linkage (7) to one electro motor (5), said one hydraulic servo actuator (8) being of the type having the one mechanical linkage (7) connected to its input (29) and its output (30) and the one electro motor (5) being of the direct drive type, the position of said electro motor (5) having a reference to said one mechanical linkage (7) and the torque delivered by said electro motor (5) to the hydraulic servo actuator (8) being related to the power consumption of said electro motor (5).