Here's a question for you guys. Let's say that a fictional carrier (perhaps many) can MEL an inop main fuel tank quantity indicator (the fuel gage in the cockpit), with some very specific procedures for gassing up, and then requiring the crew to continually manually update GW based the inop side being assumed to be same fuel as the operative side (plus whatever center tank indicates). For the sake of discussion, assume this flight is at night. I presume fuel leaks aren't all that common, but in the worst case scenario where there is a fuel leak on the side that has an inop indicator, how will you know?
As you know, the QRH/procedure for fuel leak assumes you have operative fuel indicators, and uses that information (i.e. accurate total fuel) to determine if a leak exists. The notes don't have a whole lot of other real great ways of recognizing a fuel leak. It seems that eventually you would get a lo press light on the bad side pumps, which wouldn't really do much good. Don't think the fuel imbalance indication would be operative? or maybe it would? It's night, so nobody would probably see it happening up at cruise with the wing/landing lights off. My assumption is that this would present itself as an airplane that is requiring more and more rudder trim (in autopilot) to keep wings level, and then you'd get fuel pump lights followed by that side flaming out. And then your life would quickly go to •.
Maybe a more interesting reverse case would be a suspected fuel leak on the known good side. That just seems a little too evil though.
I realize this is probably a good question to ask in recurrent, but I figured it might at a minimum, highlight a lack of my systems knowledge, or maybe even a good discussion
