There are various possible ways for making crashes appear somewhat more realistic, we talked about possible methods for doing this about a year ago:
http://www.flightgear.org/forums/viewto ... d=a#p28308As you'll see, back then I was also thinking in terms of using different models (parts), animations and sub models for modeling the "crash".
But doing this would be far from realistic, it would be more about entertainment/gaming.
To make such things work and look more realistically, an approach like
Rigs of Rods would need to be used.
To do this right, one would then also need a different way for creating aircraft, to specify hull structure, material properties etc
But there are apparently now several people interested in this sort of thing (just think in terms of the bombable or missile addons).
Also see:
http://www.flightgear.org/forums/viewto ... art=0&st=0