Fuel line routing...Seaplane version

[DBeaulieu]

Started to work with fuel line routing ideas. I have the Patrol Seaplane QB and the left side fuselage door is a mirror image of the standard QB Patrol kit fuselage right side door. I would like to see how others have run the fuselage fuel lines (which takes from fuel tank rear outlet) and runs down the vertical rear former, under the door sill, past the forward door former and to the bracket where the bulkhead T junction is mounted. I've posted my method from the T fitting and past the rear former. Not sure what I am going to do to join the vertical and horizontal runs,but doesn't seem apparent to me it can be done with one singular run of tubing. Also considering running my fuel line inside the frame at the front door former rather than passing thru ...there is adequate clearance from the fuselage tubing and the flap mechanism. If anyone can show how they routed their fuel lines on the right side of the fuselage that would help me with perspectiv/possibilities on the sides of mine. Thanks so much!

Cheers! (Dave from Maine)

fuel line 1.jpg fuel line 2.jpg

[Viking]

Here is how I did mine. Someone with well more skill and patience may have been able to make this line in one piece, but I couldn’t figure out how that would be possible, and stole someone else’s idea of installing a bulkhead fitting in the top stringer for the line to pass through. Where the line goes through the second stringer, I cut a slot to allow myself clearance to gradually bend the tube up and through the slot. I installed this line starting from the forward end of the fuselage and worked aft, bent the joggle you see for the tube to attach to the T fitting, and then passed it through the forward door former as low as possible. From there, it slopes up as much as possible, passing just below the bottom door former and through the aft door former. I was then able to work the tube through the slot in the stringer, and bend gradually up to meet the bulkhead fitting in the windowsill. I used 3003 tube for my lines, so it wasn’t too much effort to bend the large radius in position. It looks pretty agricultural in my opinion, but it gets the job done, and provides for just about the best downhill slope you could have passing under the door. Also, none of this will be visible once my interior is fabric covered, so it doesn’t have to be real pretty.

[DBeaulieu]

Thanks Viking, that's what I kinda came up with for my plan of attack while starteing to mock-up with 3003 tubing. Looks like I can do a straight pass thru bulkhead on the lower stringer with the line passing thru the rear former with a large enough cutout to allow a bit of maneuvering room and let the front end of the tube with the B nut at the T pass thru. That way I can do all my flaring on the bench then insert into position. Pics to follow once mock-up complete.

Dave (from Maine)

Fuel line run.jpg

[Viking]

That sounds like a good plan to me. Interestingly, it looks like your bracket that the T fitting mounts to is several inches farther forward than mine, which would have made my installation a bit less complicated. The only potential problem you may have is getting that hole in the forward door former large enough for the B nut to pass through. I routed my line low enough that there wasn’t enough room between the fuselage tube and the flange on the former, so I had to bend the forward end of my tube first, then flare and install the b nut and then feed it aft through the door formers. I was able to make my bend behind the rear door former and then bend the tubing out a little to get the flaring tool in there to complete the line. If any of these lower lines ever fail, I’m going to have to remove my interior fabric to replace them. They should last long enough that the aircraft will need to be recovered by then anyway.

[DBeaulieu]

I am even considering cutting the horizontal line, beading the ends at the cut and using a very short piece of rubber hose to reconnect. With no inside fabric under the door and good support for the connected tubing it seems like that would allow for easy inspection and replacement of the individual lines if ever necessary. The beaded line end on the "front" section would pass thru the front former and the rear former pass thru is already large enough for the B nut on the other half of the line. Thoughts anyone?

[N3UW]

I posted some photos of what I did on my patrol. I put a fitting on the vertical section behind the door post. This configuration allowed positive slope in level flight and ground position. I also had to lower my fuel false slightly with a custom bracket to keep prevent any low points to trap water that was not at the sumps. I also wanted to keep the lines as close to the door post as practical. I coved the chafe points with glue filled heat shrink and on some areas used the old piper technique of wrapping with cotton friction tape then sealing the tape with shellac

[DBeaulieu]

N3UW Thank for posting the pics John, it all helps! I'll see if I can manage those bends on the forward top tube

Dave (from Maine)

[Bcone1381]

RE; the welded fuselage fitting that recieve the Bulkhead TEE....The key point is that the fuel lines must be secured at a certain interval that I've forgotten....12"? 18"? That fitting on my 2017 fuselage was just in the wrong place. I spent days prototyping fixes. I just could not use the fitting and make the bend towards the fuel valve and negotiate the fuselage structure all at the same time and so I cut if off. To secure the fuel line I used a series of cushion tube clamps. It very solid.


So keep an open mind as you build. It seems to me like the fitting has been moved since 2017 and I think it probably in a better location now.

[DBeaulieu]

Was wondering about that Brooks and why you had cut them. I'm seem to recall spacing is 16" for fuel and electrical run but need to find the reference...

[500AGL]

Dave,
I ran mine as one piece, based off Dave Lenart's reccomendations.

The first set I ran using the larger space and hole in the lower "a-pillar" former, but I ran into trouble getting my bending tool close enough together to make the S bend I needed to finish it to the fitting. The left side is still this way and I believe I can make it work. The right side I just remade and looking at some photos I had of the other Dave's, I ran it through lower in front and it was much easier to connect to the fitting.

The rest of the run requires holes drilled and lots of on/off, repeat, repeat as required to bend it complete.

pb

[DBeaulieu]

What I ended up doing on both sides. 45 degree bulkhead in lower side stringer, thru the door rear former joined midway with rubber hose (on beaded ends) to forward tube passing low through the front door former. I plan on not having interior fabric in that area under the doors, so midpoint connection is easy to inspect and maintain. Both sections of line are able to be removed with exterior fabric and boot skin in place.
right side fuel line run.jpg