They should really have type certification diffs. If 90% of the airplane is the same as the previous version, the manufacturer should expect a type certificatio

They should really have type certification diffs. If 90% of the airplane is the same as the previous version, the manufacturer should expect a type certification procedure that costs about 10% of a fully new design and pilots should gain the new type rating with about 10% of the effort and hours of what would be required for a completely new plane. It sounds really cumbersome to have it either-or way, making it difficult to develop planes too much incrementally and keeping it very costly to start from scratch with a completely new design.