Originally Posted by
ShyGuy
This is an old article, before the media reported correctly on MCAS. MCAS was required to mimic current NG pitching behavior at higher AOA. The MAX could have been certified without MCAS, but at the expense of needing a new type rating.
The media has not once, ever, reported correctly on MCAS.
SECTION 25.203 Stall characteristics.
§ 25.203 Stall characteristics.(a) It must be possible to produce and to correct roll and yaw by unreversed use of the aileron and rudder controls, up to the time the airplane is stalled. No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall. In addition, it must be possible to promptly prevent stalling and to recover from a stall by normal use of the controls.
I am not going to go dragging out the Advisory Circular guidance (AC 25-7D) on flight test. It is written for engineers and basically says stick force per G has to be constant approaching a stall. Because of the bigger engines, they created a lifting force close to stall, in accelerated stall testing. Not high AOA, which is why MCAS is only active with Flaps up. No adverse characteristics with flaps down stalls. MCAS makes the stick force per G constant in accelerated stalls, that is a requirement for Part 25 Aircraft certification, has nothing to do with a common type rating. Common type rating only refers to the amount and type of training required.
The DC-10 and MD-11 do not have the same stall characteristics and they have a common type rating, as do many other aircraft.