Originally Posted by
HighWind
This is a huge task to design from scratch.
Even moving hardware from a more modern aircraft like B787 to B737, and then adapt the software to handle all the differences in hardware interfaces (protocols etc), user interface, difference in control laws etc.
Do Boeing have a military variant of the B737 with a more modern flight control system, that can be reused on the MAX?
The Seattle Times article (from which the quote by
Zeffy comes) does not give many details. Indeed, designing a dual-channel system would be a huge task, but the B737 already has two FCCs running in parallel, and proving independent displays to each of the two pilots.
AFAIK only one of these is operational at a time, but they can be flight-switched by the pilots, so they must both be active.
My understanding is that the proposed changes only affect the output to the horizontal stabiliser, not all of the other flight controls, which would be a huge task. Since both FCCs are running at the same time, the required task is to fetch those few parameters that control the horizontal stabiliser, and share them between the FCCs. I appreciate that there may be issues of timing and protocols, but it is not impossible to imagine that this can be done, given the many months Boeing has spent analysing every detail of the MAX.
Changing the hardware or FCC protocols is a complete no-no, since this would involve fresh certification and training, and IMO may not be necessary if only a single flight control is being monitored. The whole point is that it should fail-safe, and revert to the pilots, not try to fly the aircraft autonomously.
Leaving the horizontal stabiliser in the last known good position would seem to be a sensible choice, and the aircraft should be controllable in this state. Flipping the trim cutout switches, and reverting to manual trim would remain an option (as before), though a lot less likely to be needed.