It is sometimes difficult to tell if there is damage, until complete failure at a later date. I was just getting used to a used Cermark SU-31 I have. When I got the plane, the engine was mounted on it's side with the exhaust point up, IEthe head on the left wing. Ibought a new cowl and an flipped the engine. I also re plumbed the tank. Iscrewed that up as Ineeded to pinch off the line to the carb to defuel the tank.

The third flight, ended in a dead stick about 10 ft off the ground on take off. Iended up clipping a wing tip and smashing the new cowl. No damage to the wing. I got in a few flights after fixing the cowl and re-plumbing the tank. After a couple good flights one day, I was cleaning up to take the plane home and I discovered what looked like movement between the wing halves. Turns out that when I clipped the wing tip, Ibroke the joint between the wing halves, including the joiner ply. There wasn't anything holding the halves together other that the two dowel pins in front, the two screws in back and some shredded balsa ribs in the center. I've got it rebuilt now, but the center joint was a mess and there was a crack in the D tube on the tip of the wing that clipped the ground. Not a hint in the covering though.

A really close look at things after a rough landing is in order. Imissed the problem I had, even knowing I had some work to do. If I hadn't caught it on the clean up that day, I would have most likely had a wing fold pulling out of a dive later. Sometimes a hard landing is a crash in disguise.

Don