Abstract: A monitoring and control system for a dual-engine helicopter for OEI flight operations includes a parametric indicator operative in response to sensor signals for monitoring an engine gas generator speed parameter N1 during dual-engine and OEI flight operations. The indicator includes a rotatable needle that provides an analog indication of the current value of the N1 parameter. For dual-engine flight operations, the indicator includes a first DE indicia defining a normal operating range for the N1 parameter, a second DE indicia that defines a precautionary operating range for the N1 parameter, and a DE indicium that defines a take off power limit for the N1 parameter.

Abstract: The reference speed for a helicopter engine is incremented or decremented (237, 239) in dependence upon whether a specific range (miles per unit of fuel) has increased or decreased (236a) in a current period of time compared to the next preceding period of time, separated therefrom by at least 20 seconds (243, 244) to thereby set engine speed for minimizing use of fuel over distance traveled. Fuel is sampled only during steady flight (250-255).

Abstract: The speed 54,56 of the free turbine 40 of a helicopter engine 22 is compared 134,138 with the speed 142,140 of the helicopter rotor 10 to indicate 106,108 a specific magnitude of autorotation and the deceleration 150 of the rotor above either one of two threshold magnitudes 220,222 (dependent on the magnitude of autorotation) is utilized 81,68,69 to increase fuel flow 72 to the engine according to a specific schedule 160,162 determined by the type of autorotation, in anticipation of rotor speed droop which would otherwise occur during recovery from the autorotation maneuver.

Abstract: A helicopter engine speed reference (66) is increased (113, 103-105) in response to heavy rotor loading (108). The reference speed is faded up (113, 104) at a rather rapid rate to 107% of rated speed (114). After a fixed time interval (118), reduced rotor loading (119) will cause the reference speed to be faded down slowly (120, 103-105) to rated speed (121). If torque exceeds 111% of rated torque (117), the reference speed is similarly faded down (120, 103-105).