Folk:
Assuming nothing in the tank itself is broken or misconnected, it is *not* possible for fuel to leak back into the wings through either the overflow or the pump. The overflow line is what sets the fuel level in the header. When fuel reaches the correct level the overflow line is no longer "under water" and fuel stops flowing back to the wings. The fill pipe is *higher* in the tank than the over flow line, so fuel can *never* under any circumstances flow back through that line as it is never below the level of the fuel in the tank. What can go wrong? First, I've seen the two lines switched, so the fuel level is higher than it should be and the inlet is below the fuel level in the tank. Usually this results in a complaint of fuel on the windscreen. If the pump check valves leak then fuel could go back to the wings, but should stop when the fuel reaches the level of the fitting, which is where it should be normally, anyhow. This situation should be corrected as in an emergency it would not be possible to stop that extra fuel in the tank from dumping into the engine compartment should one of the lines on the pump fail. The other problem is a crack in one of the lines or fittings (depending on vintage) that allows fuel into either the overflow or the fill line at a level below the intended level. One way this can happen is if someone is careless with a fill nozzle when filling the header tank manually. John Cooper Skyport Services www.skyportservices.net _____ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.339 / Virus Database: 270.12.68/2175 - Release Date: 06/14/09 05:53:00
