This SAE Aerospace Recommended Practice (ARP) provides guidelines for the configuration and design of mechanical control signal transmission systems and subsystems. It is focused on the recommended practices for designing cable and pulley, pushrod and bellcrank and push-pull flexible cable control systems. These systems are typically used in some combination to transmit pilot commands into primary, secondary and utility control system commands (mechanical or electrical) or aircraft surface commands. On mechanically controlled aircraft, most pilot control commands are initiated through cockpit mounted wheels, sticks, levers, pedals or cranks that are coupled by pushrods or links to cable systems. The cable systems are routed throughout the aircraft and terminated in close proximity to the commanded surface or function where cranks and pushrods are again used to control the commanded function.
Rationale: Mechanical systems for transmitting pilot commands to flight control surfaces, secondary controls, utility controls, or servo control actuators are used less as electrical command transmission is used more frequently. But, mechanical transmission of primary, secondary, utility, or backup commands is likely to be the appropriate choice for some aircraft of the future. There is a need of having a document which provides recommended practice for design of Mechanical Control Systems; this ARP satisfies that need.