Big Pistons Forever, I think I know the reasoning behind most of the points you mentioned but I'm wondering about 5). I've had quite a few occasions where the fuel level sensor on a C172 would be misbehaving but I've always been happy to go, provided the fuel was dipped before departure and we had ample reserves (meaning an extra 2 hours of fuel or so, usually) for the planned flight. I'm always eager to learn, what was your reasoning for not accepting this particular issue?