Abstract: A helicopter engine fuel control anticipates changes in main rotor torque in response to lateral cyclic pitch commands, to thereby minimize engine and main rotor speed droop and overspeed during left and right roll maneuvers. A fuel compensation signal (100,101) is summed with a helicopter fuel control (52) fuel command signal (67) in response both to a lateral cyclic pitch command signal (LCP) (107) from a pilot operated cyclic pitch control exceeding a left or right threshold magnitude (201,210) and a total lateral cyclic pitch command signal (TCP) (108) from a lateral cyclic pitch control system exceeding a left or right threshold magnitude (202,207,215,220). The magnitude of the fuel compensation signal is dependant upon the direction of TCP and LCP, e.g., left or right, and helicopter roll acceleration (115). Alternatively, the magnitude and duration of the fuel compensation signal is dependant upon the rate of change in commanded lateral cyclic pitch (107,400,407).

Abstract: In an aircraft automatic flight control system, automatic shutdown (42) of the roll axis thereof (FIG. 1) as a consequence of faults detected therein also provides automatic shutdown of the yaw axis thereof (180) in the same fashion as detection of faults in the yaw axis (171, 167) provides shutdown of the yaw axis. Coupling of the roll axis shutdown into the yaw axis shutdown allows determining which of three axes cause lighting of a single trim shutdown indicator by resetting the yaw shutdown register (145) and simultaneously resetting both the pitch and roll shutdown registers by means of a single cyclic pitch control switch. Automatic yaw trim outer loop and yaw inner loop stability systems are disclosed (FIG. 2).