Originally Posted by
GlobalNav
I'm m
How can you be sure the standards are inadequate? I think it’s more likely the process of delegation and signing off on compliance. If exiting standards had been complied with, this would not have happened.
Item 1. 25.255 requires a maximum demonstrated out of trim of 3 seconds at applicable trim rate, that then will provide controllability for the pilot to manage the pitch to be able to pull 1.5 g with no more than a normal short term limit of force applied by a single pilot. The MCAS exceeded the trim rate applicable so that misses the target, available pitch to achieve g was not available, and it appears the force applied comes from two pilots, in excess of the single pilot short term force...
Item 2. Whatever it is called, MCAS was a SAS system, and the consequences from a failure of any SAS system, as well as the warning/alert seem to be way off the mark IMHO.25. 672
If pitch control is inconsequential then there is no problem. The smoking hole in the ground suggests that is not the case.
NB: my reservations on the compliance of the design does not mean the design cannot be acceptable, all applicants in a PSCP may propose an ELS to meet the requirements of certification. In this csse, that would need to have considerable safety training or additional system architecture to be reasonable.
Out of trim is a global issue for systems with manual trim as the reversionary mode. That is not just the Max, or NG.
The Max happened to introduce a new vector towards pain. The earlier designs are less likely to get so far into the rough but they can and then they all have the same handling issue. Adding a high torque backup would be a major undertaking, but that is what exists on many Boeing like the 777, 747betc. The Airbus has a manual trim backup.... But that the control of the hydraulic motors of the THS.Lose both hyd sys and no THS changes possible.