Originally Posted by
EXDAC
Perhaps I misunderstood you but, to be clear, AD have never applied to E/AB aircraft. AD can apply to certificated components, such as an engine, used in E/AB.
While its rare, ADs have long been applicable to non-TC aircraft and products provided the AD applicability statement specifically identifies that non-TC item. There’s been FAA guidance on this and even some notable E/AB OEMs have stated this in their documentation as well.
And conversely, if you do use a “certified” engine on an E/AB you do not need to comply with the AD for the certified version unless the AD applicability statement specifically addresses those engines installed on non-TC aircraft. By installing that engine on your E/AB it loses its "certified" status regardless if it still has its data plate or not.
The principal basis for this is every issued AD is a new Part 39 regulation under which there are no exemptions to their compliance. The AD applicability statement is the key to whether the AD is applicable to your E/AB or not.