Well I'm on my 5th hour of flight and I came a cross a small problem. Some times, not all the times I get a loud Very loud buzzing sound from what I think is the rear of the canopy. It tends to happen when it is cold and I have the heat on. When I turn the heat off sound go's away. My canopy is very tight and so is aircraft. Do I need a vent? and has anyone else had this problem.