I flew mine all last season, and about half way through I noticed a 4.5 inch vertical crack on one side of the fuse behind the gear plate, just in front of the wing pin hole. The fuse was completely cracked through except for the finish on the outside, so I took it home and fixed it from the inside with BVM carbon fiber mat and CA, and so far it looks like it's holding. One of the things I noticed however, was that the carbon fiber reinforcement from the factory extended all the way past the wing pin hole on the uncracked side, and was about 25 mm short of the wing pin hole on the cracked side, so my theory is that this is what caused my problem. If I get any more Integrals, this is going to be one of the first things that I check. There are other things I going to do as well:

1/.. As above, make sure that carbon fiber extends past the wing pin hole.
2/.. Reinforce the fuselage sidewall area between the gear plates with carbon fiber skinned nomex board and epoxy to prevent the fuse from buckling.
3/.. Reinforce the air hole in the bottom of the fuse with carbon fiber mat and CA to prevent the fuse from buckling at the edges of the hole.
4/.. Reinforce the eges of the air hole in the front of the belly pan with carbon fiber mat and CA to prevent the edges from cracking at the creases on the side.