Fuel line routing in the wing question

[Brad Ripp]

My kit is pre-owned and one of the wings is 90% complete and sealed. I noticed in the manual that the aux tank fuel lines are made to run down the aft side of the wing. The completed wing has the fuel lines running along the forward side. Any reason why this is not good? And if so, is it worth trying to re-run lines with access only by inspection covers? would NOT be fun. I would think not?? Also, the transfer line from the aux tank to the main tank is direct. I like the idea of running it into the forward site guage for indication as to when the aux tank is dry. Instead of removing the existing line and replacing to the site gauge, I'm going to T off the existing transfer line and split it to the site gauge also. This way I may even get an increased transfer rate? Other than a couple extra fittings, does anyone see a problem with this? Thanks!
Brad

[Mark Goldberg]

Brad - look at the BearTracks or the Book that came with your plans. It shows the fuel system layout Bob Barrows recommends. You would be wise to stay with that. Mark

[Brad Ripp]

Mark, I do agree. BUT... one wing is sealed and plumbed from the previous owner. My big question is whether there is a big enough reason to move the fuel lines to the rear of the wing (while doing it only through access panels). Other than when you hit something, you usually do it from the front, I can't think of reason it makes a difference. So I'm fishing for a reason. Everything else, (gascolator, fuel selector, etc) is according to plan.

[rodsmith]

So the line from aux tank to main tank enters the main tank on the outboard side? There is nothing wrong with that except I understand your desire to have an empty tank indication with it plumbed to the sight glass line. I do not see how it could be rerouted with a closed wing. If you split the discharge to two points the majority of flow will go the route of least resistance, may not give you the desired result.

[whee]

I haven’t looked at the aux tank routing for a couple years and I did not install aux tanks in my plane. I would stick with Bob’s design as Mark said and wouldn’t split the discharge for the reasons Rod mentions. Once you get used to the transfer operation I think it won’t be a big deal. If the PO did a quality job of installing the fuel lines and the only difference is that they run along the front of the wing rather than the aft of the wing then I wouldn’t bother with changing them.

[JimParker256]

James Weibe (www.beliteaircraft,com) sells a couple of sensors that could be useful for the Aux fuel tank crowd. One is a fuel sensor that measures the quantity of fuel by the pressure it exerts on the sensor (with digital gauges to match). The other is just a “bingo fuel” sensor that tells you when the tank reaches the pre-set level (empty or maybe 5 gallons remaining). Pretty cool technology.

[Bcone1381]

I like that fuel pressure sensor too. I get the Heebee Geebies when I think about a site gage failure.

[marcusofcotton]

$15 on ebay, 1/2" NPT though.

https://www.ebay.com/itm/NEW-W-E-ANDERSON-DWYER-OLS-10-OPTICAL-LEVEL-SWITCH/202212936963?hash=item2f14d48d03:g:9WoAAOSw37tWAWTL

[Brad Ripp]

Thanks guys, all makes sense. I came to the conclusion that splitting the lines wouldn't really help the flow rate because it's only going to go as fast as the source no matter what. I plan to hang the wings and mock up some tests between the wing I'm doing (by the book) and the one done already. After looking in there a bit further, I did see that it will be "very" difficult to change the first wing, although it can be done with some help of drilling out the curved piece that seals the wing/flap joint. As Whee mentioned, I don't see a big enough reason to go through the trouble. I thought I had realized the benefit of by running them in the aft end of the wing, that it would be a down hill travel for any water issues so as not to trap any (freezing issues, etc.) I then realized that the plan calls for routing to the site guage by going around the aft end of the main tank and then "up" to the top guage tube....which creates more uphill travel than the other. Thanks for all your input, I have confidence to test it and figure it now. It's just good to ask even the stupid questions because sometimes someone has points that you'd not have realized and wish you would have!
Bcone, I liked the site guage because I assumed it's probably the most reliable of anything out there. I'd think you can easily figure out whether they are accurate or clogged in any way by changing the attitude of the plane and watching for the expected reaction. Am I missing something? Plus, the other fail safe is the glass cockpit software telling you how much it "thinks" you have to be able to compare the two. Thanks,
Brad