Originally Posted by
tdracer
The 'grandfathered' portion of the cert basis had nothing to do with the MAX problems. Everything that has been identified as a shortcoming in the MAX has been associated with new (e.g. MCAS) or significantly modified/affected systems (e.g. cable separation for rotor burst) needed to be certified to the latest regulations per the Changed Product Rule.
It's not the cert basis of the MAX that is a problem, it was the execution of the cert.
There are 2 issues, one is in the event of rotor burst, the Max has a lack of control cable run protection ahead of the wing similar to the NG which Boeing claim has not proved to be a problem with the CFM56, but the LEAP 1B is a different engine in a different location with presumably a different rotor burst path and therefore could hardly be compared accurately to the NG....
The other issue is the lack of power cable separation for the electric trim control system which was also an issue on the NG and did not meet the relevant FAR when the NG was certified, but was missed by the FAA.