'Ello!

Ahhhr! They're enoug to make you pull your hair out at times eh? Have had a similar problem in the past from time to time, though never with geometry so simple. It really is a little perplexing.

I note that the fuselage has no history, how about the wing? It's had it's history deleted too?

One time I've even had the boolean operations 'switch' with the functions not doing their own operation, rather one of the other two ops. Very weird.

I can only suggest a few things to try.

No doubt, you've resaved the file and tried again. How about exporting all the objects in your scene? Turn off texture refs and history and all the rest of the jazz, and just export the wing and the fuselage. Load the new file and try again. If it works, just move the fuselage and the wing in the original file off to the side then import the newly created file with this combined part in it. Though I've only had this method help me once.

Other times, I've had the hypergraph filled with all kinds of junk that didn't need to be there. All looked fine until I hit the Show All Conections button, whereupon all hell broke loose.

To be honest, I think that this last trick is your best bet.
1)Select the 6 faces on the fuselage that the wing intersects.
2)EditPolygons->Extract
3)Select wing, shift select this new object of only 6 faces, hit boolean again.
4)Polygons->Combin booleaned geometry with rest of fuselage
5)Select all verts in the object and do Polygons->Merge

Just make sure that the merge tolerance is set nice and low, 0.01 or so and you'll have no trouble with unwanted merging. On the other hand you could merge the verts pair by pair if you'd prefer to do it that way.

S.