Originally Posted by
Bleve
The MAX has larger engine casings that are mounted further forward than earlier 737's. At high AoA's, those engine casings start generating lift, which creates a nose up pitching moment. The MCAS is designed to counteract this by creating an opposite nose down pitching moment through the stabiliser.
So why would FAA/Boeing give pilots an AD that tells them that their current NNL/QRH/Abnormal procedure is sufficient to deal with an MCAS runaway, if the procedure done correctly will disable the MCAS, without then warning that they shouldn't depend on MCAS, if the pilots knew they had it, to protect them from the nose up pitching moment in the flight regime where it might occur, that FAA/Boeing has not yet defined other than hand flown approaches (?) to a stall in some envelope or steep turns? Was MCAS even necessary given that FAA/Boeing don't even tell pilots to worry about it once it's disabled by the NNL/QRH/Abnormal? Did they hurriedly pencil whip a system to deal with an outlier that conflicted with Part 25 and was not in the normal flight regime but if you decided to do steep turns in the airplane as opposed to the simulator you might get in trouble?