Fuel systems

[Mitch Taylor]

The mechanical pumb will draw from the aux tank, but if there's air in the lines (because you ran the main dry) it will take quite a while to get fuel flowing again. The system I use when flying longer trips it to take off and fly the first hour on the mains. After that hour, switch to the aux tanks for an hour. At that point, switch back to the mains. The return flow from the aux tanks will have topped the mains back up, and you will have a small reserve remaining in the aux tanks. The Air Force dash one says to run the aux tanks dry, then switch back to the mains, but I don't like things getting quiet suddenly. As far as landing on the aux tanks, there are two reasons not to. First, if the engine stutters, no boost pump. Second, there isn't a sump on the aux tanks, so you can unport the fuel pickup in a turn or bouncing around.