AlephZero said:143 gives the maximum permitted pilot forces to safely control and maneuver the aircraft.
398 says the maximum loads on the flight control surfaces must never exceed what would resullt from the given pilot forces.
In other words, 143 is a limit on the physical strength the pilot needs to have, to fly the plane "normally" in a safe manner. 398 says that if the pilot applies a greater force to the controls (for example in an emergency situation), the control system much stop the pilot from damaging the aircraft by applying excessive force to the control surfaces.
FAR 23.397 is a regulation set by the Federal Aviation Administration (FAA) for the airworthiness of small aircraft.
FAR 23.143 is also a regulation set by the FAA, but it specifically addresses the requirements for aircraft fuel systems and their components.
The main difference between these two regulations is their focus. FAR 23.397 covers general airworthiness requirements for small aircraft, while FAR 23.143 specifically addresses fuel systems.
While they have different focuses, both regulations are part of the same set of rules and standards set by the FAA for aircraft airworthiness. They both aim to ensure the safety and reliability of small aircraft.
Yes, both FAR 23.397 and 23.143 apply to all small aircraft, including airplanes, helicopters, gyroplanes, and airships, that are used for non-commercial purposes and have a maximum takeoff weight of less than 19,000 pounds.