Originally Posted by
Speed of Sound
A simple question which I’m not sure has been discussed.
If the original amount of MCAS authority was required for certification, then how can the revised software which gives MCAS a reduced authority, still fulfil certification requirements and if it does, why then was an excessively powerful system allowed on an aircraft when that power and authority was in excess of what was required for certification?
As I currently understand it, the revised MCAS software will be able to move the stab the same amount, but will be subject to more “checks” (dual AOA, speeds) before it does so and will only be able to make this input once, as opposed to repeatedly, as it could in the original version. A significant amount of stab movement will still be necessary to meet the certification requirements for the low-speed, high-AOA condition. In the high-speed, high-AOA case, MCAS will only input the smaller amount (about 0.6 degrees, IIRC)