Originally Posted by
Sunfish
Boeing took a design that was not intended to run active fly by wire systems and then added flight dynamic control software (MCAS) and perhaps other stuff onto an avionics infrastructure platform that was never designed to cope with mission critical flight control. There needed to be three systems, voting, separate busses, permanent magnet generators, etc. etc. to implement MCAS as a mission critical system.
It looked like a 737, but it was a kludge.
There are two more new, quasi FBW systems added to the MAX that have not gotten much attention. One is the "Landing Attitude Modifier", added because of the 9" nose gear extension.
"To maintain acceptable nose gear contact margin, LAM symmetrically deploys flight spoilers on approach to reduce lift and force the aircraft to use a higher angle of attack. The amount of spoiler deflection depends on the approach speed. Deflection begins approximately 10 kt above VREF."
The other is the "Elevator Jammed Landing Assist System", added because...?
"If a jam occurs in the aft elevator control mechanism, both control columns have a limited range of motion. During approach and landing, the Elevator Jam Landing Assist System uses the flight spoilers for small changes to the flight path."
In an email exchange on 5/29/2015, our favorite Jedi Master is talking with his sidekick about the "jammed elevator/DLC" (I don't know what DLC stands for.)
"I suck at flying jammed elevator without DLC"
"It's tough, huh?"
"I crashed big time my first few times, that's what scares me about showing this to any of them. You can get decent at it after 3-4 tries, but the first few are ugly."
"They are going to tweak the elevator effectiveness a little. Yeah, we talked about using a reasonable cg to make it doable without dlc. We want them to succeed without DLC". [If they can't show that it can be flown without DLC, then it wouldn't be 'just like the NG'.] "it is easy to start chasing pitch and power and get in a PIO."
"ultimately, you have to have it trimmed up pretty well when you start your appr descent, and the thrust coupling is way more effective than the DLC, at least that's what I found. you of course have to pretty much disregard your airspeed
"
[I can't wait to try it out. The conversation continues, a little farther down....]
"unfortunately I think she is going to suck so bad at flying them, she's going to demand this be trained in the sim. I started thinking last night, what if we mandated the training in the NG starting in 2016, so everyone was trained on it ahead of MAX, (like RCAS?) if there [sic] real concern is being trained on it in general, then it should be sufficient to get everyone trained on the NG, the theory being again that if you can do it in the NG, you can do it in the MAX."
I can't find it now, but there was another conversation about installing a system (RCAS?) on ONE NG, then it wouldn't be a change on the MAX, because the NG had it. It was somewhere in a conversation about Lion Air.