Heres what happened to a FEJ F16 1/5.5. Elevator flutter due to poor elevator torque tube design. This bloke was offered a new jet on the proviso that he basically shut his mouth on it. I could post heaps of these as I used to sell this rubbish in the early days. I saw the light!
This is a pic of the pipe on the first test start of the same jet. Threw stainless shards clean out the back.
You be the judge.