lomapasseo,
Much of the judgement about human-system interaction is in the application of AMC 25.1302 ‘Installed Systems and Equipment for Use by the Flight Crew’ (I assume that you are familiar).
The application and processes for the 737 Max failed.
The requirement is ‘relatively’ new such that early versions of the 737 may not have had a full evaluation. The industry has struggled (continues to do so) with the human aspects. The dependence on judgement vs hard regulation requirers that both manufacturers and regulators understand and agree critical assumptions and justifications. This process was weakened with self certification and poor regulatory oversight, and thus the appropriate application of the requirement is central to the 737 Max re-evaluation.
The task involves both aircraft modification and reviewing / repairing the regulatory process, the latter requiring more regulators, trained and conversant with the 737, in regulation interpretation, and processes for evaluation, approval; … time.
The ‘
massive crackdown on the FAA-Boeing interaction process regarding product certification‘ is required, but it’s not directly part of the current regulatory process; who oversees the regulators. Max flights don’t depend on this as it appears that the manufacturer is largely excluded from current ‘judgements’.
Water pilot, certification stability requirements depend on increasing stick force with speed reduction (fixed trim). This is particularly important at low speed where increasing pull helps identify approach to the stall. If the force required reverses - decreases, or the aircraft exhibits tendency to pitch-up into the stall, these identify unacceptable stability characteristics without being ‘unstable’. The details are within the lengthy and complex requirements of CS / FAR part 25.
The Max appears to differ in the nature of the low speed characteristics and also when manoeuvring at high speed - use of AoA / Mach vs speed; there are few precise details.
P.S. You or others might wish to see the free course
https://www.futurelearn.com/courses/flight-mechanics stability is in week 4