Originally Posted by
Australopithecus
1.: A very minor point: FCOM is now contained in one volume
2. The FCOM is mute on the MCAS; No mention is made of it at all except in Brazil apparently. Their regulator didn't accept Boeing's assurances on the subject and hence required at least some crew training on MCAS.
3. Boeing allowed a hidden input to a secondary, but very powerful flight control based on the data from a single source.
4. Boeing maintains that the runaway stabliser checklist adequately addresses inappropriate MCAS activation.
5. Boeing's runaway stabiliser checklist starts with the condition statement “uncomanded stabiliser trim movement occurs CONTINUOUSLY”.
6. The MCAS operates in slow 9.2 second bursts, then pauses for five seconds, then acts again.
7. Depending on your english skills, the MCAS may or may not satisfy your personal trigger threshold for an actual runaway stab. I have had an unrelated stab runaway and it was neither continuous nor as trained.
8. Boeing characterised a MCAS event as less than catastrophic, hence justified their reliance on a single sensor, and a single data path, despite even that being outside the letter of FAR 25
9. Being provides no useful guidance on the ramifications of flight control malfunctions in a holistic sense. There is no mention made of elevator load relief limiting elevator deflection at speeds >300 kts. Nor is there guidance on configuration changes, Nor how to interpret an apparent unreliable airspeed/stall warning on take-off.
10. Try to handle a challenging event with the stick shaker buzzing away and the trim moving in opposition to your control inputs the way the speed trim system does on every take-off and then determine that you have another unrelated failure that needs immediate action.
Very eloquently summarised.
That Boeing fudged FAR25 and permitted a single failure point and self classified the risk as non-catastrophic will likely get the attention of the investigators.