I'm getting ready to install the rear baffles on my fuel tanks and that got me to wondering about how common fuel tank leaks are and when they are discovered. I know some builders have leaks at different times, so if you fall into this category, please just choose the answer for when you discovered a leak for the first time. If you've built multiple planes and had more than one of them leak then I'll leave it to you to choose which project to focus on.