Abstract: A vertical performance limit compensator is provided for a rotary wing aircraft. The compensator modifies a vertical velocity command signal for the aircraft's autopilot. The vertical velocity command signal represents a desired vertical velocity for the aircraft, and results in an associated engine power demand. Existing engine power remaining beyond that required for level flight is excess engine power. An engine performance signal is provided as an indication of an engine power demand that exceeds the excess engine power. A compensated vertical velocity command signal having a magnitude lower than the vertical velocity command signal is provided in response to the vertical velocity command signal and the presence of the engine performance signal.

Abstract: A control system, having an input command signal and driving a prime mover, is provided with variable magnitude and/or rate input signal limiting that is adjusted by maps 68,70,72,74 which set the limits for a variable magnitude limiter 14 and a variable rate limiter 22 as a function of the prime mover rate. The limiting is adjusted dynamically as the prime mover rate changes. When the prime mover enters an undesirable operating condition, the maps only limit the command signal in the direction of such condition. The adjustable limiting is enabled or disabled based on the position, rate, and/or acceleration of the prime mover.

Abstract: An electrical circuit for allowing electrical power to be applied to the ctro-mechanical sensors of an automatic flight control system of an aircraft only when either the Engine Start switch or AFCS Engage switch is closed separately or simultaneously. Upon the closing of either one or both of the switches, a pair of latching relays are energized which in turn provide electric power to the electro-mechanical sensors.

Abstract: The automatic heading retention mode of operation of an automatic flight control system for a rotary wing aircraft is discontinued and reestablished through the use of a logic circuitry responsive to the yaw rate, bank angle and airspeed of the aircraft and to the force applied to the cyclic pitch control member by the pilot. The logic circuitry provides for the isolation of information commensurate with left and right turns and summation of the yaw rate and bank angle in each direction to determine if automatic disengagement of the heading hold is warranted.