But, if any of those events happen, it doesn't matter how many engines the plane has. A four-engine plane is a very different beast the the twins and twin operations rules should NOT be applied to them. The FAA is showing its lack of knowledge and experience in restricting quads. But, then again, they might just be in the pocket of Mr. Boeing and Company.
GF
"A very different beast"
Yes, 2 vs 4 .
Yes, both certified to fly with a single engine out. Both in need of a diversion with two engines out. And the one with more engines has a greater chance of independent failure combinations, not to mention the myriad of risks having nothing to do with muliple engines out.
I never thought of this as a Boeing or Airbus design issue because it hurts my brain to figure out why it is good or bad.
I deal with historical data and safety analysis.
But in the greater sphere of things it's small change in contribution to overall risk, so I only get into this fray for fun
