Final answer:
The FCCs work with FCC 2 to provide command signals to maintain the aircraft's pitch and roll for attitude hold, as well as yaw for heading hold, essential functions in an autopilot system in aviation.
Step-by-step explanation:
The FCCs (Flight Control Computers), through FCC 2, provide Flight Path Stability (FPS) command signals to the pitch, roll, and yaw trim actuators. These trim actuators in turn reposition the flight controls for pitch / roll attitude hold and also heading hold in yaw. This is a standard function within an aircraft's autopilot system that maintains the desired orientation of the aircraft without constant input from the pilot. The FCCs work in conjunction with various sensors and systems onboard the aircraft to ensure the plane maintains the set altitude, heading, and orientation during flight.