If all else fails a simple mass balance will solve the problem.

Often servos that won,t stay screwed down or servos that mysteriously strip gears, pushrods that seem to fail, one or more hinges keep failing clevis keeps failing are actually just symtems of ongoing flutter that you may not even be aware of.

Yes these items will need to be fixed but that in itself is not going to stop the problem. I have never run across a case ever that sealing hinge gaps has actually stopped the problem. The one thing that will is mass balance.

Flutter analysis is a horribily complex subject and a dedicated engineering discipline in itself and its not all that uncommon to run across a design that is subject to the problem. Every problamatical design that I have had this situation with and became aware of it by constantly stripping servos or the classic maching gun sound and happened to survive the flight has been cured completely with confidence simply by mass balance either with the little guy I pictured or by imbedding a bit of lead in the forward ends of aerdynamic balances of some control surfaces.

I have taken to doing the imbedded mass balance on a number of other folks airplanes which happen to be airplanes known to be flutter problems and this does eliminate the problems at any speed at which the airplane may be capable of reaching.

Perhaps more designers should go ahead on many of these designs with the giant and flexable control surface should plan for this with imbedded mass balance.

John