Originally Posted by
PEI_3721
fgrieu, #1, medod, #4,
The basic aircraft was certificated on the basis of MCAS. The theory and inservice experience confirmed that this option is satisfactory, excepting for AoA malfunction.
I don't think that's accurate. First, by definition, theory can't confirm anything. And it is doubtful that MAX with MCAS 1.0 saw enough inservice time to confirm that it was satisfactory except for AoA failure.
Technically the second iteration of modification appears to be satisfactory.
We have nothing but weakly-sourced reports about MCAS 2.0
The aircraft is not inherently unstable; there is a reduction in stability margin in small areas of the flight envelope, which MCAS alleviates.
Again, none of us have seen data on the aerodynamics of the bare airframe. And many, including JATR, think it would be wise to find out just how it behaves in those corners without MCAS.
There should not be any significant concerns about abnormal flight without MCAS - after an inhibit - an assumption.
Yes, so far, just an assumption.
The aircraft has ‘normal’ stability characteristic in most areas of the flight envelope - as demonstrated with lengthy time in service
The MAX has not had "lengthy time in service."
- but how often did MCAS work.
If anyone has any clue as to the answer to that question, it certainly hasn't been made public.
Crews can be alerted to the need for care in the less stable ‘corner points’ when flying without MCAS.
Assuming that the airplane can be certified to fly without MCAS.
How does a non MCAS Max differ from the NG; do aerodynamic differences effect the ability to trim with the wheel ?
Unless the regulations change, one way it differs is that it can't be certified.