Originally Posted by
DozyWannabe
@infrequentflyer789 - While you are correct in asserting that one should not hear the Stall Warning in Normal Law, and as such hearing it is an indication that something has gone wrong - as I understand it, the warning and annunciator system is not directly connected to the flight control logic - so it is never switched off or suppressed by anything directly. The FCU is a network of loosely-coupled, real-time processes with a degree of redundancy built in - not a monolithic, closely-coupled design.
Yeah, I know. I simplified a bit. SW doesn't directly inhibit anything, but once stalled it is likely that airdata discrepancies will start to show up due to the stall, and trip the plane out of normal law. That's assuming the SW is valid.
It's probably possible to take a broken bus and fly to SW in normal law and then recover without leaving normal law. Not sure I'd want to be in the back when someone tried it though. The guys at Perpignan were in direct law within 10secs of SW - see p112 (english version) of final report.
@rudderrudderrat:
See the traces on page 112 of the Perpignan report - SW clearly in normal law.