Originally posted by Harley Condra
When re-fueling, please don't make the mistake of leaving the UAT fill line unplugged. If you have an air leak at the fill line plug, you will soon have a flame-out because the pump will pull all of the fuel from the UAT instead of from the main tank(s) and header.
I use a Festo 6mm one-way checkvalve instead of the plug that comes with the UAT. You could also use a Festo 6mm ball valve if so inclined. Turn it on to refuel, turn it off when full.
Harley is absolutely spot on with the air-leak scenario.
I previously used a one-way check valve. I recently had my first ever flameout, and was
incredibly lucky to have it happen a hundred feet or so into the takeoff roll, rather than a couple of seconds later. Turns out that air had leaked in through the one-way check valve.
I replaced it by a 6mm ball-valve, and additonally use a stub of fuel tubing with a plug in it which I push in to the outer end of the ball-valve. This gives me a level of redundancy - if the ball valve leaks, then the plugged stub may save the day.
Lemme know of the above description is unclear - if so I can take a pic tomorrow & post it here.
Regs,
Gordon