Question: Difference between FAR 23.397 and 23.143

[jonathanpun]

Hi,
Can anyone here can explain to me the difference between FAR23.397 and 23.143?
What's the maximum and minimum force represents in 23.397?

 

[AlephZero]

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.

 

[jonathanpun]

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.

Then I think that FAA will only quote the maximum force in 397. Why they quote the minimum force in 397? It's meaningless?

 

[AlephZero]

See the cross-reference in Note 2 to wind gust loads on the control surfaces when the aircraft is on the ground (section 415). That gives one use for the "minimum" values in the table in 397.

I'm not a "expert" on this part of FAR, but in general, it's hard to understand individual regulations without getting the big picture of how they fit together. Reading the whole section from 391 to 459 might help.