Fuel tank fittings- interference with root rib

[High Country 69]

So I'm just about ready to install my new wing tanks into my hybrid wing. I'm using Brett's 13 gal tank and the fittings don't quite line up with the lightning holes in the root rib. the main fuel out directly hits on the rib if I come straight out so do I notch the rib right near the spar and weaken it or do I put on an elbow to go around it. I hate to take away from any structural integrity especially in this area but also don't want any interference with fuel flow. also I want to make the sight tube stick out onto the outside of the butt rib the top hole also hits on the rib so do I just drill a hole put a 2 1/4" brass pipe through the hole then add my 90* then the sight tube. Doug I think you built wings like these how did you do it, do you happen to have any pictures by chance?

Thanks Robert

sorry for all the questions but I want to do everything the best that I can.

[EDMO 1078]

It is listed in Kitfox instructions to cut a clearence notch where the fuel outlet meets the rib - However, I think an elbow might be a better choice for both locations. Maybe you will get some better suggestions.

ED in MO

[dholly 718]

@Robert -

I used the old Skystar slip-in style wing tanks for my Mk-IV, not much help for you as they had a bottom sump and outlet. So did my Avid+ 'glass-in f/g wing tanks. My KF3, I had the nose tank and a 6 gal wing tank with built-in round fuel gauge, no sight tube so no help there either. The wing tank had a side fuel fitting outlet, but I also had covered root and butt ribs so not 100% sure if the rib was notched. Pretty sure it was but if you want to know definitively, search for pics comparing KF1-3 vs. Avid HH rib profiles I put here on site a while back that would show. Best I can do is show a pic of my KF4 root rib. Yes, it does require notching for clearance when using a straight out side fitting. No worries, it's not enough to compromise overall wing strength. I would use straight out fittings with finger strainers, I would not use elbows on wing tank outlets, too easy for a small piece of debris to get hung up and cause problems. For the sight gauge tubes, I would simply drill a hole through the rib web to allow the tubing to pass through and connect to a straight out fitting. An extension is unnecessary IMHO and just adds a potential leak spot. I reworked the sight tubes on my KF4 to extend past the root rib and added a cover. Looks pretty good and makes it easier to see the clear mogas in the tubes.

Edited 31 Aug 2012 by dholly

[High Country 69]

Thanks for the reply's, I will just go ahead and notch out the ribs with a dremel to make clearance for the main fuel out and drill a hole for the sight tube to pass through. Do you think the blue fuel line will work ok for a sight tube or should I get enough clear just for the sight tubes. Regarding the finger strainers, why is this better than using a clear filter with a wire screen placed possibly where it can easily be seen during pre-flight - http://www.aircraftspruce.com/catalog/appages/fuelfilter.php this way you could easily monitor any debris and it would be much easier to clean out as necessary.

-Robert-

Edited 31 Aug 2012 by High Country

[EDMO 1078]

Thanks for the reply's, I will just go ahead and notch out the ribs with a dremel to make clearance for the main fuel out and drill a hole for the sight tube to pass through. Do you think the blue fuel line will work ok for a sight tube or should I get enough clear just for the sight tubes. Regarding the finger strainers, why is this better than using a clear filter with a wire screen placed possibly where it can easily be seen during pre-flight - http://www.aircraftspruce.com/catalog/appages/fuelfilter.php this way you could easily monitor any debris and it would be much easier to clean out as necessary.

-Robert-

Good question on filter, finger strainer - will let more knowledgeable builders answer that. I prefer finger strainer, which might prevent stoppage and maybe the addition of a clear filter too. You could have stoppage without the finger strainer.

On the sight tube - at one time there were small red beads available that would float on top of the gas - these were used in some factory sight tubes - dont know where to get them now, or what size - but caution here, as lots of plastic beads will melt in gas and probably ethenol would be worse.

ED in MO

[dholly 718]

Thanks for the reply's, I will just go ahead and notch out the ribs with a dremel to make clearance for the main fuel out and drill a hole for the sight tube to pass through. Do you think the blue fuel line will work ok for a sight tube or should I get enough clear just for the sight tubes. Regarding the finger strainers, why is this better than using a clear filter with a wire screen placed possibly where it can easily be seen during pre-flight - http://www.aircrafts.../fuelfilter.php this way you could easily monitor any debris and it would be much easier to clean out as necessary.

-Robert-

IMHO, keeping the larger debris such sloughing off construction adhesive, bugs and whatever else finds it's way into your wing tanks, etc. out of small diameter fuel lines is imperative. If you use finger strainers and remove them as a part of each annual condition inspection, you will be amazed at how much crap shows up in your brand new and otherwise clean wing tanks. In any event, there has been so many warnings about not using fuel filters inline between wing tanks and header tanks, particularly paper filters, primarily because you can't see the fine fiberglass strands that ultimately clog and lead to fuel starvation engine stoppages. Using a glass inline filter body with the finest possible [edit] WIRE ONLY screen in conjunction with the finger strainers and a gascolater sounds ok to me but not sure if you really gain anything there. Personally, I think I'd rather see any debris that passes through the finger strainers out of the fuel system asap in my preflight sump. I don't think the Bing blue line will work for your fuel sight gauges. E10 autogas discolored mine pretty quick. I changed to Tygon 2375 Ultra by Saint-Gobain last winter and have minimal yellowing, can still see pretty good with the white background. If you don't want to get as fancy, just place a slightly bent piece of heavy white index card cut to fit behind the sight tube. Leni found the floating gas balls somewhere, search will find the thread.

Edited 1 Sep 2012 by dholly

[akflyer 1427]

http://www.bearperki...accessories.htm

Scroll down to the sight tube kit. He also has just the red floats. I am putting them in mine today if the friggin rain will let up... I ordered extra red floats when I ordered the sight tubes just for the hell of it. Thbis guy is old school and actually trusts the customers. I filled out the order form online and sent it in. A couple days later I called him because I had not gotten a call from him for my CC info. He told me the order had already shipped out and there was an invoice in the box and to just send him a check when I got it... Not too darn many guys around like that anymore that will ship out orders BEFORE getting paid for them! Great guy to talk to on the phone too, he knows his 2 stroke stuff!

[High Country 69]

IMHO, keeping the larger debris such sloughing off construction adhesive, bugs and whatever else finds it's way into your wing tanks, etc. out of small diameter fuel lines is imperative. If you use finger strainers and remove them as a part of each annual condition inspection, you will be amazed at how much crap shows up in your brand new and otherwise clean wing tanks. In any event, there has been so many warnings about not using fuel filters inline between wing tanks and header tanks, particularly paper filters, primarily because you can't see the fine fiberglass strands that ultimately clog and lead to fuel starvation engine stoppages. Using a glass inline filter body with the finest possible [edit] WIRE ONLY screen in conjunction with the finger strainers and a gascolater sounds ok to me but not sure if you really gain anything there. Personally, I think I'd rather see any debris that passes through the finger strainers out of the fuel system asap in my preflight sump. I don't think the Bing blue line will work for your fuel sight gauges. E10 autogas discolored mine pretty quick. I changed to Tygon 2375 Ultra by Saint-Gobain last winter and have minimal yellowing, can still see pretty good with the white background. If you don't want to get as fancy, just place a slightly bent piece of heavy white index card cut to fit behind the sight tube. Leni found the floating gas balls somewhere, search will find the thread.

Sounds good about the filters, My greatest concern with the finger strainer is removing it once a year. I'm a bit nervous how the fiber glass threads will hold up in the tank. I don't have any experience threading things into fiber glass though so maybe I'm nervous about nothing.

-Robert-

[High Country 69]

http://www.bearperki...accessories.htm

Scroll down to the sight tube kit. He also has just the red floats. I am putting them in mine today if the friggin rain will let up... I ordered extra red floats when I ordered the sight tubes just for the hell of it. Thbis guy is old school and actually trusts the customers. I filled out the order form online and sent it in. A couple days later I called him because I had not gotten a call from him for my CC info. He told me the order had already shipped out and there was an invoice in the box and to just send him a check when I got it... Not too darn many guys around like that anymore that will ship out orders BEFORE getting paid for them! Great guy to talk to on the phone too, he knows his 2 stroke stuff!

Nice Leni, I'm going to get a couple of these floaters, do you know if his clear fuel line is ethanol proof by chance?

-Robert-

[EDMO 1078]

http://www.bearperki...accessories.htm

Scroll down to the sight tube kit. He also has just the red floats. I am putting them in mine today if the friggin rain will let up... I ordered extra red floats when I ordered the sight tubes just for the hell of it. Thbis guy is old school and actually trusts the customers. I filled out the order form online and sent it in. A couple days later I called him because I had not gotten a call from him for my CC info. He told me the order had already shipped out and there was an invoice in the box and to just send him a check when I got it... Not too darn many guys around like that anymore that will ship out orders BEFORE getting paid for them! Great guy to talk to on the phone too, he knows his 2 stroke stuff!

Thanks for the Perkins site - I ordered 2 of the sight tube kits - Now, what is best sealer for fittings to fiberglas tanks?

I use Loctite 545 Hydraulic sealer on all metal fittings. It is OK with ethenol too. Talked to Loctite specialist (salesman?) and he seemed in the dark about fiberglas - said maybe 545 with a primer, or Loctite liquid Teflon paste????

Ed in MO

Edited 5 Sep 2012 by Ed In Missouri

[High Country 69]

Ed, I used Permatex 9AR for sealing the fittings into the fiberglass tanks, that's what KF uses. I went with the finger strainers as everyone suggested, and notched out the root ribs to make clearance for all the fittings it looks nice and i made sure there was enough space to easily fit a deep socket onto all of the fittings once installed for easy maintenance. Also started making fuel placards. How should I make them "look good" with all the makings and stuff. I was thinking just paint them white and find stickers for the hatched line behind the tube? what have others done for this?

p.s. the pink tubing in the pic is the old fuel line that came with the kit in 1986 I'm just using it to get everything how I want it, I have clear line for the final sight tube.

[EDMO 1078]

Ed, I used Permatex 9AR for sealing the fittings into the fiberglass tanks, that's what KF uses. I went with the finger strainers as everyone suggested, and notched out the root ribs to make clearance for all the fittings it looks nice and i made sure there was enough space to easily fit a deep socket onto all of the fittings once installed for easy maintenance. Also started making fuel placards. How should I make them "look good" with all the makings and stuff. I was thinking just paint them white and find stickers for the hatched line behind the tube? what have others done for this?

p.s. the pink tubing in the pic is the old fuel line that came with the kit in 1986 I'm just using it to get everything how I want it, I have clear line for the final sight tube.

Robert,

Glad the cowl suggestion worked. There was a printable download on one of the Kitfox sites long ago for the scale for the wingtanks - maybe someone can send it, or you can find it. UPS or someone can print this on a transparency or you can just glue it and cover it with plastic.

ED in MO

P.S. Thanks for the 9AR. Thought I could get off and shut up for a while, but letting paint dry on tanks tonite.

Edited 11 Oct 2012 by Ed In Missouri