Vilters,
#405,
“The main issue remains.
These "events" are triggered by failing AOA sensor/systems. => That is where the main focus should be => Why is the AOA probe/system failing.”
Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
I agree; see related questions in
https://www.pprune.org/rumours-news/618252-boeing-737-max-software-fixes-due-lion-air-crash-delayed.html#post10429320 (#381)
Also see the links giving a technical basis for a software ‘glitch’; AoA value in error.
However, as yet the answered question is:-
“Would such a ‘failure’ (glitch) be a random, probabilistic occurrence - just chance, or require an external disturbance - elect spike (FDR AoA error seen during taxi - generator switching?)”
Continuing with this hypothesis, then the focus of the investigation should be to confirm or refute the need of at least two contributing factors, what are they, and the circumstances which result in AoA error - MCAS does the rest.
If electrical, then follow-on questions should consider if any abnormal ground or in-flight switching or alternate power supply could similarly reset / trigger the initiating conditions - which could also relate to the proposed modifications.
/hypothesis.
Additionally, and perhaps the key to understanding, is why only two aircraft have exhibited the fault, and the many others in service apparent not. Noting previous linked comments about ground reset, maintenance test, and before flight electrical checks.
As a far-out thought; is the order of after-start generator or bus tie checks an option, 1 before 2, etc, is this before flight or after landing as in some other aircraft types.