lml@lancaironline.net Mailing List Archive

Bryan,

I'm afraid the setup you mention would be troublesome. I don't know if a 1/4 line is adequate or not, so I'll pass on that. Generally it is undesirable to connect both tanks together in a low-wing plane, and this might be especially true of one with low dihedral. The problem is that even a small difference in fuel level could result, as the fuel level gets low, in one tank unporting, allowing air to enter the system. As soon as air gets in the other tank will likely stop feeding entirely, shutting off the fuel supply. You could probably feed off both down to some level, but that level might be 1/2, and then there would be no reliable way to get the rest of the fuel out. How do high-planes get by with it? They run each line separately down to a common sump at the bottom of the plane. The difference in pressure would have to be larger than the head of fuel from top to bottom, about 4 feet or more.. In a low wing plane there is no vertical height available. If you had a "three-way" valve that could select R-L-H-off it could work, I suppose..

Gary Casey

I want to run this idea I have past the group.

My current set-up is 1/4" lines coming from my wing tanks to the my header. Then a 3/8" line feeds my engine. In this configuration I can only feed the engine from Header only. This is the stock Lancair 320 fuel system.

I would like to be able to run my engine off my wing tanks if needed but I don't want to re-plumb the wings with 3/8" lines. Can I connect the 1/4" wing tank lines into a "T" with a 3/8" exit and run the line to the selector valve? Essentially the wings would not be able to be selected but they would feed at the same time equally.

Would this idea work? And if so what type of Andair valve would I need? One with just a Left/Right/OFF And I would have them custom engrave the bezel to read Wings/Header/OFF

Thanks

Bryan