Originally Posted by
boxmover
Adding a spring system would involve incorporating new hardware on the Max. That new hardware would come at an on cost. The attraction of the Boeing solution is that it uses the existing hardware plus some new software.
Boeing got the cheaper solution certified so what is there motivation to go to a more expensive solution.
The question is is should it have been certified.
Why adding a spring ?
There is already an Elevator Feel System (EFS) which is controlled by a calculator, the Elevator Feel Computer module, thus it is controlled by software.
The elevator feel computer receives pitot pressure, hydraulic pressure, and mechanical inputs. The elevator feel computer sends metered hydraulic pressure output to the dual feel actuator on the elevator feel and centering unit. Feel hydraulic pressure in the elevator feel computer varies between 180 psi (base feel) and 1400 psi (maximum). The actual feel pressure to the dual feel actuator is determined by the hydraulic pressure from system A and system B, pitot pressure, and stabilizer mechanic
(from www.satcom.guru)
So, if the issue at stake was just about restoring the linearity of the control pitch force versus AoA angle, this could have been done just by enhancing the EFS system algorithms.
Just one little issue: the FCC doesn't feed the Elevator Feel computer with the AoA information.
It bet that Boeing engineers have balanced this against creating a new software function called MCAS whose implementation only affects the FCC module.
Now that the implementation costs of MCAS appear to be vastly different from the initial estimates, Boeing might reconsider enhancing the EFS.
I mean, that route might be preferable to adding even more complexity to a MCAS module whose existence and purpose is debatable.