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Yo, Alan, The engine-driven transfer pump can fill the header (fuselage) tank at a rate so greatly exceeding maximum possible fuel consumption that the return line(s) cannot keep up. If the 1/16" restrictor fitting is not present on the fuel pump discharge line or if you have an overflow line blockage or restriction, the tank will overflow onto your windscreen! Excess fuel drains back into the wing tanks (via one or more oveflow lines depending on fuel system fitted) which then equalize via the line between them. If your wing tanks were empty and some fuel was consumed from the fuselage tank, fill the fuselage tank first. Any excess (above the overflow line inlet height) will drain into the wing tank(s) while you fill them. If not, just fill the wing tanks. Your header tank is already at the "normal" level (overflow line inlet height). If you were to fill the wing tanks fully and then fill the header tank (with no way to know when you have filled beyond the overflow tube inlet). the excess would drain down into the (full) wing tanks and out of your wing tank cap vents (if present). If you don't have vented wing tank caps (and everything else seals perfectly) it may be possible to gain a bit of fuel capacity by filling the header tank last (to the top) after filling the wing tanks, thereby gaining the extra capacity between the "normal" level and the actual available total volume of the header tank. Always having had vented wing tank caps, it has been my practice to fill one wing tank as full as I can and then the other the same way. The first filled quickly starts flowing into the other through the equalizing line, but at a far lesser rate than possible with the fuel hose. By the time the second wing tank is to the neck top the originally filled tank will be down about the amount which, when the tanks again equalize, should minimize any initial airbourne slipstream loss (assuming you don't have tank vent problems, which is a whole 'nother can of worms). Leaving tanks full at the end of a flying day will minimize the amount of air in the tanks to absorb moisture. You should find less water on the next preflight fuel check than if you waited to fill the tanks. (see third following paragraph) If you actually see water in a preflight fuel test sample, position the aircraft with the rear directly over a tiedown and tie the tail as low as you can. Carry a hose with perhaps a foot of rigid tubing and siphon out the water at the back of all three tanks that can collect there (and corrode the tanks). In turbulence and unusual flight attitudes (wake turbulence?) such water can stop an engine when you most need it. In southern California, once a year was enough. I never saw water otherwise. In a very humid climate, this might be prudent monthly (or even weekly)...you'll know by how often you've actually found water in your fuel sample where you fly. Oh, yeah...always suspect you'll get some water when fueling at a new source. Fuel first, then go to town, eat, etc. Give any water time to settle out. Carefully check for it before takeoff. Not doing this can ruin your whole day (and your coupe)! Regards, -- William R. Bayne <____|(o)|____> (copyright 2002) ------------------- original message: on 12/20/02 4:13 PM, Kahunadude at [EMAIL PROTECTED] wrote: ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- In a 3 tank fuel system, does it make any difference in what order the tanks are filled? Should the wing tanks be filled and not the header? Is it a good idea to keep the tanks filled after each flight? Alan O <<<---N99616--->>> || / \ O O ========================== To leave this forum go to: http://ercoupers.com/lists.htm
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