Are you sure it was flutter? I had a Tiger 120, still have it as a matter of fact, anyway, it made a flutter noise. It scared the he!! out of me. I landed it and checked everything and put it back in the air. The noise came back.

Fortunately, my mentor/instructor from back a few years - - was there. We looked everything over and found nothing wrong, except, a piece of trim monocoat did not stick to the wing covering just behind the leading edge on the top of the wing. It was tight but not stuck to the monocoat underneath it and the length of the loose piece was about a foot long and parallel to the leading edge. We put a piece of "scotch" tape on the length of where it was loose and put the plane back in the air. The noise was gone.

CGr.