Originally Posted by
Less Hair
But then it cannot be certified at all. By the nature of grandfathering it carries over old surpassed technologies and standards like many other aircraft do.
I may have misunderstood you here but grandfathering/readacross is fine until new technology, in this case the engines, provides a changed threat environment, then you have to redo the safety case including additional mitigation to overcome those new threats. It sounds as if the new engines have brought a new threat against the rudder cables - from just what has been reported - but the new engines would need full certification anyway so that should have been picked up on the Max "delta certification" work. Is the FAA now saying that this did not take place?