I really need some help. I am based in nairobi kenya. I have two ex3 cubs. When either cub goes into rain - even very very light rain the aircraft vibrates and a resonance builds up to the point it is severe vibration. When exiting the rain it continues until the speed is reduced then it stops. Both the aileron cables on each wing vibrate severely, the floor etc the whole aircraft. Strangely there is very little vibration on the controls. I thought it was the gps aerial on the roof so i modified it and strengthened the whole area with a doubler. This did not help. Is it possible the skin is too lose…. Any ideas