RV-14A fuel tank internal fuel return plumbing?

[DonMcKee]

I'm starting work on my RV-14A fuel tanks. The plans call for installing a VA-141 finger strainer flange that could be used for a fuel return line:



but then have you cap it off without any additional internal plumbing:



While I don't need a fuel return line now, I would like to build my tanks so they're ready go if electronic fuel injection is somewhere in my future. I have already modified my ribs to allow installation of the VA-141 flange.

It seems to me that, internally, I need to run a flared hardline from the flange to an internal bay (#2? #3? Somewhere further outboard?), similarly to how the vent line is routed. The internal ribs already have holes that could be used to route the return line:



My questions:

• What fitting(s) do I need to use with the VA-141 flange to connect to the internal plumbing (flared 1/4" tube?), as well as some future external return line?
• Is 1/4" tube, similar to what's used with the vent line, adequate for this application?
• How far outboard do I need to route the return line? Is the second bay "far enough?"
• Will I need to fashion some type of support bracket attached to the rib at the end of the return line, or is routing through the last snap-bushing-protected rib hole good enough?
• Can the return line shoot straight out (e.g. towards the next outboard rib), or should it be directed elsewhere (e.g. forward, down, etc.)?

Anything else I'm missing? I don't know what I don't know. Thanks!

 

[georgemohr]

Since the return line is just that, a return, what makes you think you need to pipe it to a high point on the tank? I don't have an EFI so I'm just asking to understand for myself

 

[DonMcKee]

Since the return line is just that, a return, what makes you think you need to pipe it to a high point on the tank? I don't have an EFI so I'm just asking to understand for myself

My understanding is that you don't want bubbles, turbulence, from the fuel being returned to be picked up by the fuel output line. Since the return point in my application will be directly above the supply point, just dumping the fuel back in the tank could cause problems if the fuel level is "low."

 

[TS Flightlines]

My understanding is that you don't want bubbles, turbulence, from the fuel being returned to be picked up by the fuel output line. Since the return point in my application will be directly above the supply point, just dumping the fuel back in the tank could cause problems if the fuel level is "low."

The VA141 is a 3/8 NPT port. Most builders leave it open on the tank side and under fuel pressure the stream is sent to about the first rib anyway. MANY are flying with none of those bubble isssues that I know of. NOW---you could modify the VA141 to accept another fitting from the inside, with a piece of tube.

 

[RossK]

SDS recommend 4 inches between pickup and return, so I've got the pick up at the rear and the return at the front in my 7A tanks, plenty of room, and all accessible from the access panel if need be.
Still a long way from flying, so no proof it works....

 

[bruceh]

Don’t fill up those empty holes at the top of the tank ribs. They allow air flow out of each bay as you are filling your tank with fuel.

 

[Foghorn]

I’m running SDS with 370 hrs and no issues.
The return line should be the same size as the fuel pickup. My return is mounted low on the tank and goes into the second bay over from the fuel pickup and is a straight tube. I just used a snap bushing to support the return line through the second rib.

 

[DonMcKee]

The VA141 is a 3/8 NPT port. Most builders leave it open on the tank side and under fuel pressure the stream is sent to about the first rib anyway. MANY are flying with none of those bubble isssues that I know of. NOW---you could modify the VA141 to accept another fitting from the inside, with a piece of tube.

I'm not familiar with what my options are with respect to available fittings, apart from what were included with my kit. If I understand your post correctly, you're saying that I can carry on and build according to plans (i.e. install the VA-141 and plug it), and all will work out fine if/when I need to put the fuel return to use. Do I understand this correctly?

 

[TS Flightlines]

I'm not familiar with what my options are with respect to available fittings, apart from what were included with my kit. If I understand your post correctly, you're saying that I can carry on and build according to plans (i.e. install the VA-141 and plug it), and all will work out fine if/when I need to put the fuel return to use. Do I understand this correctly?

Yes sir. PLUG the VA141, or go ahead and install a AN816-6-6D and a AN929-6D flare cap to close the port. Then if you ever decide to use the returns, just unscrew the cap and plumb the external lines.
Tom

 

[DonMcKee]

Yes sir. PLUG the VA141, or go ahead and install a AN816-6-6D and a AN929-6D flare cap to close the port. Then if you ever decide to use the returns, just unscrew the cap and plumb the external lines.
Tom

Okay, Build On it is! Thanks, Tom!

 

[maca2790]

I'm using the Andair Fuel pump and a Lycoming with the Standard Fuel Injection system, so I don't need Fuel Return lines. Has anyone here not installed the Upper VA141s with their tanks?

 

[czechsix]

I'm using the Andair Fuel pump and a Lycoming with the Standard Fuel Injection system, so I don't need Fuel Return lines. Has anyone here not installed the Upper VA141s with their tanks?

You need to fill the hole with something anyway, IMO it's best to install the upper VA-141's per plans and then use pipe plug to seal it. There's always that chance that you might change your mind on engine and/or fuel system. Having provision for fuel return allows you to use EFI with a Lycoming or the new DeltaHawk diesel...with all the uncertainty around the future of 100 octane avgas, keeping your options open is a good idea.

 

[bertschb]

Has anyone here not installed the Upper VA141s with their tanks?

Had I known what this was used for when I was building my tanks, I wouldn't have drilled the hole to add the upper VA-141. Just another place for leaks. Yes, nice to have the option for a return line...for whoever buys my airplane when I'm done flying.

 

[maca2790]

Had I known what this was used for when I was building my tanks, I wouldn't have drilled the hole to add the upper VA-141. Just another place for leaks. Yes, nice to have the option for a return line...for whoever buys my airplane when I'm done flying.

Hi Brian, my thoughts as well. Why drill the holes and make all that mess in the first place!

 

[maca2790]

You need to fill the hole with something anyway, IMO it's best to install the upper VA-141's per plans and then use pipe plug to seal it. There's always that chance that you might change your mind on engine and/or fuel system. Having provision for fuel return allows you to use EFI with a Lycoming or the new DeltaHawk diesel...with all the uncertainty around the future of 100 octane avgas, keeping your options open is a good idea.

There is no hole in that location. If one reads forward to the Wing attach instructions the return fuel line is not even mentioned or shown in the drawings.

 

[Bavafa]

I'm using the Andair Fuel pump and a Lycoming with the Standard Fuel Injection system, so I don't need Fuel Return lines. Has anyone here not installed the Upper VA141s with their tanks?

I did not install it on my second 14 as I did not see a need for it since I will not have any return lines.

 

[Bavafa]

You need to fill the hole with something anyway, IMO it's best to install the upper VA-141's per plans and then use pipe plug to seal it. There's always that chance that you might change your mind on engine and/or fuel system. Having provision for fuel return allows you to use EFI with a Lycoming or the new DeltaHawk diesel...with all the uncertainty around the future of 100 octane avgas, keeping your options open is a good idea.

There is no pre existing hole, one needs to be drilled if planning on having a return line.

 

[czechsix]

There is no pre existing hole, one needs to be drilled if planning on having a return line.

Wait so you guys are telling me you actually have to drill a hole on the RV14? I thought Van's pre-punched everything Anyway...it's been a while since I finished my tanks. Obviously provisioning for the return line is optional, but it's way easier to do now than later...even if you are sure you want a traditional Lycoming dinosaur up front, your airframe might be flying for the better part of the next century and the most promising new powerplants & fuel systems that will run Jet A or Mogas have fuel return lines. The next owner will thank you...

 

[TS Flightlines]

There is no hole in that location. If one reads forward to the Wing attach instructions the return fuel line is not even mentioned or shown in the drawings.

There is no mention in the plans, because Vans doesnt support the SDS/EFii systems. BUT were forward thinking enough to provide a port for them in the tank rib. If you dont use the returnsm just cap them off. If you decide later, the port already there.

 

[georgemohr]

I think you would be best to install them. The installation is easy and there are far more difficult places to seal on those tanks, I really wouldn't worry about that at all. You never know what the future will bring for engine tech.