An actuator assembly comprising: a screw shaft having a shaft axis; a nut mounted on the screw shaft; a drive arrangement comprising a motor and a gearbox in a housing, the assembly characterised by: the housing being pivotally mounted to a frame, the drive arrangement pivotally supported around the screw shaft axis for driving the screw shaft; and a rod mounted at a first end to the housing of the drive arrangement at a location off the shaft axis and at a second end to the frame, the rod for providing a primary function of reacting torque around the shaft axis on the drive arrangement, the rod having a rod axis and being arranged to provide a load path that experiences load in a direction along the rod axis in reaction to torque on the drive arrangement, wherein the rod comprises a device (106,108) which provides a secondary function of detecting a performance of the actuator assembly based on load experienced along the rod load path reacting torque on the drive arrangement, wherein, to provide the secondary function, the device comprises a load limiter configured to control a change in length of the rod through axial movement of one portion relative to another when a load along the rod load path exceeds a pre-load of the load limiter. a screw shaft having a shaft axis; a nut mounted on the screw shaft; a drive arrangement comprising a motor and a gearbox in a housing, the assembly characterised by: the housing being pivotally mounted to a frame, the drive arrangement pivotally supported around the screw shaft axis for driving the screw shaft; and a rod mounted at a first end to the housing of the drive arrangement at a location off the shaft axis and at a second end to the frame, the rod for providing a primary function of reacting torque around the shaft axis on the drive arrangement, the rod having a rod axis and being arranged to provide a load path that experiences load in a direction along the rod axis in reaction to torque on the drive arrangement, wherein the rod comprises a device (106,108) which provides a secondary function of detecting a performance of the actuator assembly based on load experienced along the rod load path reacting torque on the drive arrangement, wherein, to provide the secondary function, the device comprises a load limiter configured to control a change in length of the rod through axial movement of one portion relative to another when a load along the rod load path exceeds a pre-load of the load limiter. the housing being pivotally mounted to a frame, the drive arrangement pivotally supported around the screw shaft axis for driving the screw shaft; and a rod mounted at a first end to the housing of the drive arrangement at a location off the shaft axis and at a second end to the frame, the rod for providing a primary function of reacting torque around the shaft axis on the drive arrangement, the rod having a rod axis and being arranged to provide a load path that experiences load in a direction along the rod axis in reaction to torque on the drive arrangement, wherein the rod comprises a device (106,108) which provides a secondary function of detecting a performance of the actuator assembly based on load experienced along the rod load path reacting torque on the drive arrangement, wherein, to provide the secondary function, the device comprises a load limiter configured to control a change in length of the rod through axial movement of one portion relative to another when a load along the rod load path exceeds a pre-load of the load limiter.