Originally Posted by
TallFlyer
People seem to forget that the crux of the 737s current issues is that the weight height was originally designed around a low bypass turbofan design, and later iterations had to deal with that original design choice. They made it work well on the NGs, not so much on the MAX as that engine design was significantly larger than the CFM56.
Correct, however engine mounting wasn't the only challenge to fielding the MAX. There were other aspects of the 737 design that, while approved during the initial certification in the 60s, would never be approved as part of a new type cert today. The rudder cables running along the side of the fuselage face danger of being severed in the event of an uncontained engine failure, as an example.
https://www.moonofalabama.org/2019/0...certified.html
The FAA more or less held up their noses and approved the MAX, in spite of this. Reference this quote form the linked article.
F.A.A. managers conceded that the Max “does not meet” agency guidelines “for protecting flight controls,” according to an agency document. But in another document, they added that they had to consider whether any requested changes would interfere with Boeing’s timeline. The managers wrote that it would be “impractical at this late point in the program,” for the company to resolve the issue. Mr. Duven at the F.A.A. also said the decision was based on the safety record of the plane.
Fool me once, shame on you. Fool me twice, shame on me. While I don't think the FAA would strictly forbid a new model of the 767 under the existing type, I'd imagine they're going to be a lot less lenient on what they approve. That said, the 767 was originally certified in the late 70s (as opposed to the 737 in the mid 60s), so one would hope there would be fewer issues.