Originally Posted by
silverstrata
And the engines are much more powerful - up to 30 k lb of thrust. All that extra thrust, low down on the airframe, generates a large pitch up moment - especially if the aircraft is slow and the elevator is becoming less efficient. You can actually get to a situation where the aircraft simply goes vertical, or flips over backwards.
S
Ah, no they are not... The maximum engine ratings on the Max are very similar to the corresponding models of the NG. The larger models are allowed more thrust because the increased leverage of the tail (due to the longer fuselage) permits it. This is all governed via the rating plugs on the FADEC - and there is logic on the aircraft side that will put up a warning if the engine ratings are too high for the aircraft model.
This is nothing new - the 737 'Classic' -3/4/500 models had the same max thrust limitations - but it was done mechanically. The 737-3/4/500 models all used the same engine, one the shorter -300 and -500 models, there was a physical stop to how far the throttle could be advanced to prevent excessive power nose-up from becoming an issue.