The RR dart is a single spool 2 radial compressor engine. the HP cock ie Hi pressure cutoff is a mechanical lever that also will disable the AFX on the other side. The power is controlled by a single lever which controls engine RPM between around 7200-15000 RPM cruise normally set at 14,200 with fuel datum trimmers set to control temps/fuel flow, as i remember you could control the FF+/- 7% of total set by the FCU. some guys I used to fly with wanted the torques matched others fuel flow others temps