Hi Lone Wolf (+CW),
That's a Clip thing.
Your plane has several hooks, some of them have special meaning (like Nav lights, gear clips, engine smoke and flames etc.), some are just named "_Clip" with a two-digit number following behind.
Lisek posted a list of clips here:
https://www.sas1946.com/main/index.php/topic,14387.msg152693.html#msg152693The "_Clip<xx>" hooks are responsible for all kind of object collision, including ground collision, so all bigger parts of your plane should have a Clip hook where it could collide with something else - that can be many clip hooks per mesh.
There's a rule to the "_Clip<xx>" hooks that says that they always have to be in a row without gaps inbetween.
The game will simply ignore any Clip behind a gap, so make sure there aren't any.
For instance if you have _Clip00 through _Clip03 for your turbine blades and _Clip04 through _Clip39 thereafter, and then proceed with _Clip41 through _Clip95, all clips following no. 39 will be ignored.
Best regards - Mike