Originally posted by A0283: "As a designer/manufacturer, WHATEVER you run into, you don't want to 'break the Type Certificate'. Breaking the TC is not only very costly but will also cause substantial delay. "
Gysbrecht's post: I would think that virtually ANY change to an approved type design requires an amendment to the Type Certificate.
DaveReidUK's post:Yes, of course. But the A0283's point was that having to amend an existing TC is greatly preferable to the FAA/EASA saying that the manufacturer has changed so much that it's essentially a new type and has to be certificated from scratch.
In general terms there are many different types and levels of 'changes'. Some - listed in decreasing level of certification impact - would require a new type certificate (breaking the TC), some a type certificate amendment, others neither.
Generally, the lower its certification impact, the easier it is to get a change implemented. In quite a few cases certification impact is estimated by the manufacturer and can be enough reason to select a design option with less certification impact. You would of course go to EASA/FAA when you to be sure of an estimate or get a process going.
On the other hand. You could say that having a large number of changes that are blocked on account certification impact are part of the reason for manufacturers to move up to a new model or even new type.