A self-propelled power trowel, for finishing a concrete surface, which comprises: a rigid frame means adapted to be disposed over a surface, the rigid frame having a front and a rear and defining a centerline from front to rear; an engine assembly for powering the power trowel supported by the rigid frame; a pair of rotor assemblies (30, 32) for frictionally contacting the surface and supporting the rigid frame on the surface, tiltably connected to the rigid frame and operably connected to the engine, with each of the rotor assemblies (30, 32) comprising a plurality of troweling blade assemblies with troweling blades configured for adjustable pitch; one or more steering actuators or mechanical linkages operably interconnected between the rigid frame and each of the rotor assemblies for tilting the rotor assembly fore and aft and left and right; a first pitch actuator operably connected to a first rotor assembly, with the first pitch actuator configured to controllably change a pitch position of the troweling blades of the first rotor assembly; a second pitch actuator operably connected to a second rotor assembly, with the second pitch actuator configured to controllably change a pitch position of the troweling blades of the second rotor assembly; Characterised by a first troweling blade pitch position sensor for detecting and reporting a pitch position of at least one of the troweling blades of the first rotor assembly; a second troweling blade pitch-position sensor for detecting and reporting a pitch position of at least one of the troweling blades of the second rotor assembly; a control unit for receiving a pitch position signal from each of the first and second troweling blade pitch position sensors, and controlling, via the first and second pitch actuators (58, 60), the pitch position of the first and second troweling blades of the first and second rotor assemblies (30, 32); and a manual pitch mode and synchronous pitch mode with control logic that provides for manual or synchronous-twin-pitch control of the first and second rotor assemblies (30, 32) and the ability for a trowel operator to selectively switch from one to the other pitch modes. a rigid frame means adapted to be disposed over a surface, the rigid frame having a front and a rear and defining a centerline from front to rear; an engine assembly for powering the power trowel supported by the rigid frame; a pair of rotor assemblies (30, 32) for frictionally contacting the surface and supporting the rigid frame on the surface, tiltably connected to the rigid frame and operably connected to the engine, with each of the rotor assemblies (30, 32) comprising a plurality of troweling blade assemblies with troweling blades configured for adjustable pitch; one or more steering actuators or mechanical linkages operably interconnected between the rigid frame and each of the rotor assemblies for tilting the rotor assembly fore and aft and left and right; a first pitch actuator operably connected to a first rotor assembly, with the first pitch actuator configured to controllably change a pitch position of the troweling blades of the first rotor assembly; a second pitch actuator operably connected to a second rotor assembly, with the second pitch actuator configured to controllably change a pitch position of the troweling blades of the second rotor assembly; Characterised by a first troweling blade pitch position sensor for detecting and reporting a pitch position of at least one of the troweling blades of the first rotor assembly; a second troweling blade pitch-position sensor for detecting and reporting a pitch position of at least one of the troweling blades of the second rotor assembly; a control unit for receiving a pitch position signal from each of the first and second troweling blade pitch position sensors, and controlling, via the first and second pitch actuators (58, 60), the pitch position of the first and second troweling blades of the first and second rotor assemblies (30, 32); and a manual pitch mode and synchronous pitch mode with control logic that provides for manual or synchronous-twin-pitch control of the first and second rotor assemblies (30, 32) and the ability for a trowel operator to selectively switch from one to the other pitch modes.