Last Saturday I was helping one of our new members. He had just soloes about 2 weeks earlier so he put together his "second plane" The plane was an old Seagul Plasma ARF low wing sport plane that apeared by all counts to be a good choice for him since he trained and soloed on a 40 size Space Walker. This was however his first complete assembly. Anyway, we are at the feild going ove the build and checking controls for proper direction and movement. I noticed the elevator halves were not aligned properly (one was up the other was down) so we made the adjustment. I then asked him, "You did balance the plane right?" He assured me he did. He wanted me to maiden the plane for him. Satisfied with my inspection I agreed to take it up for him. As soon as the plane broke ground it started climbing. elevator input was very touchy and to make things worse the ailerons needed an excessive amount of trim and were sluggish to respond. Knowing altitude is my freind here I get the plane up as best I can and trim the plane as well as possible. I finally get straight level flight but still have a very sensitive elevator. Many here have already guessed. The plane was very tail heavy. I managed to get the plane on the ground in one peice and said, lets check the ballance. We drained the tank and I flipped the plane inverted to see where it ballanced. It was then that I discovered it was about 1.25 inch behind cg and he told me he ballanced the plane upright, not inverted. After adding about a half of pound to the nose the plane flew great. He did not fly the plane this day. Sunday he's back, with the plane ready to fly. He makes a few warm up flights with his Space Walker then puts the Plasma together. He takes off like a warbird with a long roll out on the mains with the tail flying. Beatiful enough to make his instructors eye tear up. He flys for about 20-30 seconds then during an aileron roll one wing seperated from the rest of the plane. It was horrific watching the plasma spiral away to the ground while the wayward wing panel fluttered aimlessly down. Upon crash recovery it was observed that the main spar channel in the wing that seperated in flight had no significant damage. The spar itself seperated cleanly and had a nice shiney coat of epoxy thinley spread over it and no evidence that it had adheared to the spar hannel in the wing. The wing halves were joined with too little epoxy and was only held on by the epoxy between the two root ribs of each wing half. The plane only lived for a day and a half. It only had 2 and a half flights. But it tought the owner and this guy a few things