What orientation for the fuel tank fittings?

[alexM]

I'm prepping my fuel tanks for installation. I chased the threads for the fittings and then did a test fit to make sure everything went according to plan.

Being tapered threads (NPT) I'm concerned about tapping them too deep, which would fall in the category of "bad". With that in mind all I have done so far is chase the threads to clean them up, and not made them any deeper.

The sight gauge and vent fittings don't concern me but the main fuel fitting should probably be oriented in a specific direction shouldn't it? With the finger screen and elbow in place, one of my fittings points to the rear of the aircraft. The other one comes to a stop while pointed forward and slightly up. Say, 10 O'clock if it were the right tank. I know that's not right but I'm trying to figure out how it should be oriented.

Should it point straight back, straight down, 45 degrees down/back, or what? How many threads should still be visible on the finger strainer and barbed vent fitting? My plastic fittings for the sight gauges go in quite a ways but don't bottom out, so I think I'm okay there.

Thanks in advance.

[Cherrybark]

I had the same concerns about orientation and possibly screwing up the threads. Kitfox sells banjo fittings that neatly solve this problem and let you adjust orientation when finally attaching the fuel lines. I'm sorry the photo doesn't show the parts clearly. Basically, a female plug is screwed into the tank then the banjo bolt and fitting screw into the plug. The Amazon link shows a typical banjo fitting.



https://www.amazon.com/Single-Banjo-Style-Fuel-Fitting/dp/B075FHKPX1

[bumsteer]

+1 on banjo fittings. Well worth the cost.

Rick

[Denalifox]

Alex, I used the provided elbow fittings and cut the threads about a 1/16" from bottoming out. reason for this is maximum thread engagement. Also left me some wiggle room for when you apply the thread sealer acting as a lubrication. ive had fuel in my tanks for a few months now with no leaks. I think where builders are running into problems with them leaking are not cutting the threads deep enough and not having enough engagement. also I pointed my aft and down just slightly.

[jiott]

I also used the standard elbow fittings provided. I oriented them straight back. I don't remember cutting the threads much deeper, just cleaned them up. Have been leak free for 8 years now.

[Dave S]

Used the supplied fittings like Alex and Jim. It is critical to use the designated sealant. I also fabricated an access panel below the fitting to easily swing the fitting for removal and inspection. Flying since 2009 and no leaks.

[alexM]

Great responses everyone, thank you. After posting my question I found myself in the Final Assembly chapter where the fuel system where the images show the fuel tank elbow pointing straight back, but didn't see anything in the instructions about the orientation. Given the statement to make sure it is an uninterrupted downhill run to the header tank it seems like a a good idea to point it just a bit downward also.

The banjo fittings have appeal but an online search left me with more questions than ever. If Kitfox sells them that seems too easy. Unfortunately this week they seem slammed while trying to get ready for Oshkosh so I don't want to mess with my pending order.


Used the supplied fittings like Alex and Jim. It is critical to use the designated sealant. I also fabricated an access panel below the fitting to easily swing the fitting for removal and inspection. Flying since 2009 and no leaks.

Ah! Now I know why the bags of parts associated with fuel tank installation came with access panels. They made no sense to me why they'd be in there.

Edit: My paper manual for the series 7 says to use Permatex Tack & Seal 9AR. Is that what all of you have used, or is there something better?

[Dave S]

Alex,

There is some potential confusion on the permatex product as the company has changed the name and the Item #.

It is currently called "Tack & Seal Gasket Sealant" item # 80938; however, the tube has (9AR) in parenthesis below the current item number.

If you do a search on the list for "fuel elbow access" you can find some photos of what some list members have done to make access easier and certain other modifications they have make to the elbow to make inspection and maintenance easier for this little item. FWIW - The access panel I fabricated for the wing fabric below the elbow was not in the instructions - just one person's choice. In my photos I did not have one of the little plate (just the reinforcing on the fabric); but, it is held in place by two sheet metal screws.

You are making good progress.:)

[mike92104]

I haven't installed them yet, but I ordered these:

https://www.ebay.com/itm/361015704420

They were a recommendation from someone on the forum, but I can't remember who. They seem very well made, and should make installing the fitting a breeze.


Looks like ACS has something similar:

https://www.aircraftspruce.com/catalog/appages/banjo.php