A guy I fly with had the same thing happen to his. He was flying straight and level at less than half throttle (.46 XLS), he was running maybe 25-30MPH and started getting flutter big time. He landed the plane and went over it with a fine toothed comb. Everything appeared to be perfect, so he took it back up. Same thing again, except this time it didn't come home in one piece. To this day, we still don't know what caused it. He bought another, but has yet to get it in the air.

I'm definately not trying to start anything here, but I think that as long as a plane is flown with the reccomended size engine, and is being propped to perform how the plane is meant to perform, the plane "should be able" to withstand higher speeds with no problems. If there is a chance that the plane can't handle higher speeds, and those speeds may not be what we would call "fast", maybe GP should put a warning in the manual.

Just my thoughts,

John