(Koopas Ly) wrote:

The only time that fuel is set to one particular tank is on the
ground. I've never used fuel from only one tank in flight. Why would
someone do that?

One reason I was given was "so when the engine stops you can try the
other one."

This was from someone who had been test flying a homebuilt, and the
builder apparently hadn't done a good job of cleaning out his tanks
while building...