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by na85 1906 days ago
>As I understand it the aircraft has a quite complex relationship with trim because of fundamental aerodynamic flaws (engines are too far forward).

That's not really correct. The engines being in a different position means the aircraft doesn't meet a very specific criterion of the FARs (positive stick force gradient). The 737 Max has the exact same relationship with trim as any other airliner.

>Am I right in saying other aircraft e.g. an A320 would handle this sort of failure without as much risk to the plane?

No. TFA explicitly states this issue was not related to MCAS. It's likely an analogous failure on an A320 or a 737NG would still have necessitated aborting the flight.

1 comments

One thing that has always bothered me about how MCAS was implemented - if it truly was a stick force gradient issue, why not make the change in the Elevator Differential Feel Computer, which already manipulates the stick force gradient during approach to stall, rather than physically moving a control surface? Aside note, the elevator feel computer is a mechanical / non-electronic computer that is stuffed full of aneroids and solenoids and cams and followers and servovalves. Straight out of the 1950’s.
Where have you been all through the 737 Max debacle! It's refreshing to read someone who genuinely understands this issue.

And for what it's worth I've pondered that before and my only conclusion was as others have said here, probably a lack of detailed organisational knowledge on the design of the pitch feel computer. Perhaps there are confounding factors, it has its own pitot tube but not a AoA vane for example. Or perhaps changing it may have triggered more regulatory oversight than MCAS did (unfortunate given events which followed).

>Aside note, the elevator feel computer is a mechanical / non-electronic computer that is stuffed full of aneroids and solenoids and cams and followers and servovalves. Straight out of the 1950’s.

That's likely why they didn't. That type of change is hard to conceal and far more difficult to keep out of the documentation. A software change could potentially be handwaved. Full on revamping of said system would probably have edged a regulator enough to have raised an objection or a deeper dive into the nature of the reconfiguration.

A software change could potentially be handwaved

This to me seems a much greater process failure.

Maybe that's why, I don't blame engineers who didn't want to touch it...