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Wing root fuel filters

qtrmiledan

Well Known Member
Does anyone have any pics of wing root filter installs they can share? RV9 planning SDS install. Thanks in advance! qtrmiledan at cox dot net
 
Does anyone have any pics of wing root filter installs they can share? RV9 planning SDS install. Thanks in advance! qtrmiledan at cox dot net

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Here's a photo from Flightlines of an RV-14 wing root setup.
 
Danny, I installed what is shown in the photo and it is a good setup. I took out the single fuel filter just aft of the fuel pump as a result. In the 14 it is a pain to get to for service and the wing root setup uses standard car filters.
 
Here is a pic of mine. I got the bracket drawing from a fellow VAFer. I modified it slightly. Its a tight fit for sure if you have the larger filters like I do. I ended up doing lots of test bends to make sure I could get it all put together.
 

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On my -7 I did nearly the same setup as Ray. Milled two UHMW blocks to fit the curve of the filter (Andair), bolted the block to the fuse side and held in place with screw type hose clamps. Easy to reach for R&R and all the spill goes into a drip pan. Clean

Highly recommend this approach, should be standard.

Cheers
 
Addition of an inline fuel shutoff like what Flightlines offers in their kits would have made cleaning the filter much easier, but this installation was done over 10 years ago, well before they came up with the better way to do it!
& this was a SDS fuel setup.
 

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My mistake! RV9A!

Thanks for the suggestions! I failed to list in the request it’s an A model- different fuel line routing. Any “A” pics out there?
 
7 and 9s have the tank port generally across from the side skin exit, unless you are using inverted pickups in the tank nose. So lots of ways to do this---as long as the inlet and discharge end up being across from each other.

Typically to make things easier, we use a AN833-6D 90* bulkhead fitting in the side skin, and turn it forward in the wing root. Yep---the cabin plumbing has to change alittle, so pre-planning is required. Generally the filter is located on the fuselage side as there are more substantial places to secure it. Whatever way you do it, the fuel is turned 180*, and since its on the suction side, give alittle extra thought on the plumbing layout.

Just ways we've done these---not written in stone, but examples that were done for clients. There is room for an Aerolabs unit, but is gets pretty tight. Definitely mods to the root fairing to support the unit is needed. For those needing/wanting a gascolator, thats pretty easy to do too.

Tom
 

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For those needing/wanting a gascolator, thats pretty easy to do too.

Tom

Tom - would you happen to have any pics of your solution for the installation of a gascolator in that same location? Would love to see how you make this work.

This comment coming from Canada where so many builders seem to feel it's impractical to install a gascolator at the wing root. The Aerolab unit looks like a technically astute solution to that challenge, offering both the low point sump and drain as well as filter functions of a gascolator. Clearly the Aerolab units are not cheap. Buy once, cry once.

I'm sure Tom & Steve have some other solutions which would be very well suited to the task.
 
Here is what I did on a -14. I am glad I did as getting to the tunnel is extremely difficult. The tank drain is the lowest point on the taildragger for water contamination and the gascolator for any debris. The Aerolab flush mounts are very nice and makes pulling and checking the screen a 2 minute job. No fairings to remove and no tools required.

I should mention that I copied this design from another builder
 

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Here is what I did on a -14. I am glad I did as getting to the tunnel is extremely difficult. The tank drain is the lowest point on the taildragger for water contamination and the gascolator for any debris. The Aerolab flush mounts are very nice and makes pulling and checking the screen a 2 minute job. No fairings to remove and no tools required.

That looks slick! If I get tired of my Andair set-up, I think this would be a good replacement. :cool:
 
I dont have any real good pics. But generally the idea is the same This one was from Kriegler LeRoux on his RV14, but same general Idea.

Tom
 

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That Aerolab part really looks like a slick installation.

Thanks, Tom, for posting that pic.

We have proof positive that gascolator functionality can be installed in the wing roots!
 
Glenn,

Did you just mount the Aerolab unit on the wing / fuselage fairing? If so, is that strong enough? Looks very clean. I see you added a doubler to get the unit flush with the skin.
 
Just think about the yearly maintenance of these filters!
If you just have to open up the gascolator bowl, fine!
But if you have to open up more than one fuel line connection, also bent them aside to get the filter element out ... not a service-friendly solution and also risky. Also, the fuel lines made out of 3003 aluminum do not like to get opened and closed frequently.

Andair sell the gascolators as LEFT and RIGHT versions, makes installation easier. I'm using then as "maintainable filter", because maintenance is quite easy like this.
 
Glenn,

Did you just mount the Aerolab unit on the wing / fuselage fairing? If so, is that strong enough? Looks very clean. I see you added a doubler to get the unit flush with the skin.

Yes directly to the fairing with a doubler. That area is extremely strong. I don't remember the thickness of the wing root fairing on the RV-14 but it is substantial.
It is not that wide of an area and there is also a support coming out from the wing as you can see in the attached picture. This makes a pretty strong area that the fairing is screwed to. There is absolutely no flex to the fairing.
 

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So I see folks adding filters or mini gascolators in each wing root area and comments about tail dragger as lowest point. ​Is this in the building instructions now or builder modification / option. This topic has been beat to death I guess, but please educate me. Is this necessary? Is the the fuel systems per plans (mine is 2004 vintage) not recommended anymore?

When you sump your tanks you drain the tank directly in the back corner of the tank truly the lowest point in a TW or Trike. Yes? If water gets in the tank it should be there (water sinks in gas to the lowest point). You can drain all water before flight. (You should never have water but that is another story.)

Typically a main gascolator is on firewall of many planes (Trike or TW) strains sediment and water. If you sump you tanks (in theory) it will catch all water before this. ​The lower firewall gascolator is a "local low", especially in level flight. It can be drained to see if water got in system since previous flight.

It seems like adding more filters and gascolators in each wing root, is adding complexity, maintenance. How do you service those inline filters in the wing root? You have to remove the fairing and break fuel line fittings. How do you assure they are clear and water free before each flight?

What am I missing. Is this a must have or builder option and sufficient overkill. It is cool but thinking weight, more connections slightly more maintenance as a Cons. You gain what?

Having Gascolator on hot side of firewall can add heat to fuel and possible vapor lock... which is a reason I can see for doing the wing root thing. But you can put heat shield and air blast on gascolator to minimize this. OR OR Put it on the cool side of firewall and drain through floor board drain fitting. One AEROLAB flush drain behind the firewall (cool side) would be cool (pun intended). :)
 
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This is about an EFI install. Filters are preferred to Gascolators.
I got you. This is recommended by the SDS EFI fuel system manufacture, YOU... :D

From the EM-5 manual (as you know, you wrote it, ha ha).

Fuel Filters
All fuel tanks should have screen type finger strainers on the fuel feed lines and/or 40-50 micron filters between the tanks and the pump inlets. We supply a large 40 micron filter for the pump inlet and smaller 40 micron one for the pump discharge. Be sure to check the filters annually. On new build
aircraft, construction debris can clog filters leading to pump damage or a loss of fuel flow which can cause a partial or complete power loss. On the pressure side of the pumps, always be sure that any filters used are rated to at least 100 psi. and use 3/8 lines or AN-6 fittings.

Gascolators
We don’t recommend the use of gascolators with our EFI systems as they serve no useful purpose with a high pressure return type fuel system. If regulations require them, best to install them on the high pressure side between the pumps and injectors and use them as filters. Be sure gascolators are rated to at least 100 psi.


I am still not 100% sure why you can not put one filter between selector and the dual fuel pump pack on the low pressure side (e.g., an Aerolab flush gascolator in cabin/cockpit floor b4 pumps aft of firewall)? The instructions just say a filter between tank and pumps. However you answered my question. Thank you very much. Cool system, great value, amazed at your ingenuity.

Even though I am rocking farm tractor technology *up draft carb* I like to learn about the FANCY stuff. :) I am tempted to convert to SDS EFI. Good to know what is involved to support a conversion from Carb to EFI. This of course includes redundant electrical system (already have that).

So to others who don't read closely like me and you missed the SDS EFI part, if you have Carb or mechanical FI and Mags you don't "need" extra tank filters, per Van's plans works well.
 
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I got you. This is recommended by the SDS EFI fuel system manufacture, YOU... :D


I am still not 100% sure why you can not put one filter between selector and the dual fuel pump pack on the low pressure side (e.g., an Aerolab flush gascolator in cabin/cockpit floor b4 pumps aft of firewall)? The instructions just say a filter between tank and pumps. However you answered my question. Thank you very much. Cool system, great value, amazed at your ingenuity.

Builders choice.

You can use 1 filter between the valve & pumps if you desire.

Or put one between each tank and the fuel valve - again your choice. Advantage for two is that if you do run into a contamination issue, you could tell which (or both..) tank(s) the muck came from.

Installing filters outside (or gascolator) again is the Builders choice. Maybe they don't like the idea of spilling fuel everywhere & smelling up their expensive interior... Maybe they would prefer to make the mess on the floor instead.

I've installed one filter just before the pumps in one plane - pain in the ____ & messy operation during filter inspection.

I've installed filters before the fuel valve along the spar in the fuel line (2 other planes) - same pains, different orientations.

I've installed filters at the wing root (see pic in earlier post), liking the idea of making the mess on the ground, in actual fact the mess was up my shirt sleeve & all over my face (residual fuel in filter & inboard fuel line... tank was drained before hand...)

So, Builders choice.. on what & where you want the mess
 
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George, Ralph answered your questions nicely. Several ways to do this properly.

Gascolators don't work for removing water at the high flow rates in EFI systems. Les Kearney actually tested this and documented it for TC.

Our recommendations are based on doing this stuff for over 20 years in aircraft, not theorizing about it. We find a reliable solution and just stick with it. Deviations to the proven method need to be carefully considered and mean you start all over in your validation process.
 
With your EFI /SDS system what is the approximate flow rate in Litres per minute with an IO 540 full power at take off?

And the same number for cruise?


Consumption in cruise will be about 1 L per minute in cruise at 100 ROP but I am curious what is actually flowing through the intake side before the rail &injectors and return.
 
Screech! Thread Drift!

Fuel flow tests (fuel line disconnected at the injector manifold) on my current plane was measured about 38gph flow rate. This was on the ground with fuel circuit disconnected prior to the press regulator valve.
I would assume when the system is hooked back up, the regulator inhibits some of the free flow back to the tank if fuel were circulating while the engine not running, so lets guess the system circulation was 35gph, & having plenty of excess volume (no, I didn't test flow rate on the closed circuit, no need & this example is offered for illustration only)

So, in operation, the system is capable of delivering up to 38 gph to the injection rail. Say if fuel flow for an engine is 16gph on take off & we go with the 35gph full circuit flow / 36psi setting on the pressure regulator, math says we should be dumping 19gph back into the tank. Similar math applies to look at the conditions in cruise with a less fuel burn rate...

Fuel burn between carb/FI/EFI basically stay similar (which is mainly dictated by pilot settings).
I'll leave the Litre-Gal conversion to you.
 
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To F1R:
PLENTY---from our flow tests at 30 psi, we got 149.6 liter/hr through MULTIPLE 90*s and the filter on the suction side of the pump. Somewhere around .66 gal/minute +- alittle. Might not be 100% calibrated accurate, but for our purposes close enough. WE used it in developing our wing root filter package.

Tom
 

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Wing root gascolators RV 14, why bother?

Each quick drain Andair GAS375 aluminum gascolators has a 49 cm2, 70 micron stainless steel woven mesh filter coated with PTFE. Suppose to prevent water to pass through the wire screen by keeping the water in droplet form. The 3/8” fuel line gascolators size are rated for a maximum fuel flow of 38 GPH, pressure tested to 100 PSI and designed to be installed on either side of the fuel pump. The screw on filter bowl is safety wired to a support bracket.

The gascolators are suspended and safety wired to the outside of the fuselage with 1/8 inch thickness aluminum angle. The flexible fuel lines in the wing root do not support or suspend the gascolators. There is no inference or potential inference with the aileron push rod or the tank vent, from any of the elements in the wing root.

An inline ball type shut off valve allows dry servicing of the gascolators during annual inspections. These valves are safety tied in the open position, after being serviced. The bottom wing root fairing cannot be installed with the ball valve in the shut-off position.

Why deviate from the proven VANS fuel system design?

After much deliberation, evaluating and weighing up the potential risks, we designed, installed and successfully tested the wing-root gascolators. The concept is not new or novel, but only one example of a RV14 with wing root gascolators is flying in Canada.

1. Transport Canada mandated a gascolator on all Canadian registered AVGAS aircraft. This regardless of the manufacturer (VANS) stating there is no need for one, nor the fact that this is a fuel injected engine.
Having said this, a gascolator is useful as a filter of sediment and water when flying to remote areas with questionable fuel supplies.

More recently (2020) TC allows “a serviceable fuel strainer and drains in the fuel tanks” as an acceptable alternative to the previously mandated gascolator.

2. The VANS supplied fuel system has an inline fuel filter mounted in the tunnel below the panel. At the annual maintenance inspection, you are supposed to open this tunnel, break the hard lines feeding the filter, (spilling the residual fuel into the tunnel and down to the main spar) to clean out the filter and then reassembling the hard lines. Due to the poor accessibility of the filter, I could not foresee that this is going to happen without some choice words.

3. With a central fuel filter down stream of the selector valve, there is no alternative fuel line supplying the engine in a situation where this single filter is clogged up by contaminated fuel.

4. In the wing root setup, the fuel from each tank is filtered before the selector valve. This gives you the option of switching tanks if one gascolator filter clogs up fully.

5. The wing root is an easily accessible location inches away from the wing tank sump that should be drained and inspected every time the fuel tank finger drains are sump.

6. The combined screen surface area of the two gascolators is 98 sq.cm, more than twice that of the single inline fuel filter (46.5sq.cm) in the VANS plans.

7. Trying to install a gascolator in the engine compartment in the RV 14 leads to two immediate problems.
a. The only possible and easily accessible position would be on forward Lt side of the fire wall. (There is no room on the right side, due to the oil cooler dumping hot air onto this position.)
b. Putting the gascolator on the Lt side as mentioned:
o adds 4 feet of fuel line between the firewall penetration and the engine mounted fuel pump.
o Apart from the added resistance and fuel flow loss, the proximity of the common exhaust pipe might induce fuel vapor lock despite heat sleeves or barriers to the gascolator.
o The cabin heat to the pilot, dumps hot air onto this position when the cabin heat source is closed.

60 hours, 1 annual and no down sides to report yet.
 
EFI fuel systems are different from mechanical injection fuel systems. They have much higher fuel return rates.

70 micron filters are too coarse to protect the gerotor pumps and injectors commonly used with EFI.

In a bench test carried out with a gascolator and EFI pump, the gascolator didn't trap significant amounts of water.

The Van's layout wasn't designed with EFI in mind.

This thread is about EFI, not carbs, not Bendix type injection.
 
I did the exact same installation as described below for the same reasons on my RV7A which has been flying since 2015 (300+ hrs). No problems to report. I would do it again (for mechanical fuel injection or carburetor) .The Andair gascolators are mostly for it filtering properties.

Bevan
Mechanical fuel injection (Precision)

Each quick drain Andair GAS375 aluminum gascolators has a 49 cm2, 70 micron stainless steel woven mesh filter coated with PTFE. Suppose to prevent water to pass through the wire screen by keeping the water in droplet form. The 3/8” fuel line gascolators size are rated for a maximum fuel flow of 38 GPH, pressure tested to 100 PSI and designed to be installed on either side of the fuel pump. The screw on filter bowl is safety wired to a support bracket.

The gascolators are suspended and safety wired to the outside of the fuselage with 1/8 inch thickness aluminum angle. The flexible fuel lines in the wing root do not support or suspend the gascolators. There is no inference or potential inference with the aileron push rod or the tank vent, from any of the elements in the wing root.

An inline ball type shut off valve allows dry servicing of the gascolators during annual inspections. These valves are safety tied in the open position, after being serviced. The bottom wing root fairing cannot be installed with the ball valve in the shut-off position.

Why deviate from the proven VANS fuel system design?

After much deliberation, evaluating and weighing up the potential risks, we designed, installed and successfully tested the wing-root gascolators. The concept is not new or novel, but only one example of a RV14 with wing root gascolators is flying in Canada.

1. Transport Canada mandated a gascolator on all Canadian registered AVGAS aircraft. This regardless of the manufacturer (VANS) stating there is no need for one, nor the fact that this is a fuel injected engine.
Having said this, a gascolator is useful as a filter of sediment and water when flying to remote areas with questionable fuel supplies.

More recently (2020) TC allows “a serviceable fuel strainer and drains in the fuel tanks” as an acceptable alternative to the previously mandated gascolator.

2. The VANS supplied fuel system has an inline fuel filter mounted in the tunnel below the panel. At the annual maintenance inspection, you are supposed to open this tunnel, break the hard lines feeding the filter, (spilling the residual fuel into the tunnel and down to the main spar) to clean out the filter and then reassembling the hard lines. Due to the poor accessibility of the filter, I could not foresee that this is going to happen without some choice words.

3. With a central fuel filter down stream of the selector valve, there is no alternative fuel line supplying the engine in a situation where this single filter is clogged up by contaminated fuel.

4. In the wing root setup, the fuel from each tank is filtered before the selector valve. This gives you the option of switching tanks if one gascolator filter clogs up fully.

5. The wing root is an easily accessible location inches away from the wing tank sump that should be drained and inspected every time the fuel tank finger drains are sump.

6. The combined screen surface area of the two gascolators is 98 sq.cm, more than twice that of the single inline fuel filter (46.5sq.cm) in the VANS plans.

7. Trying to install a gascolator in the engine compartment in the RV 14 leads to two immediate problems.
a. The only possible and easily accessible position would be on forward Lt side of the fire wall. (There is no room on the right side, due to the oil cooler dumping hot air onto this position.)
b. Putting the gascolator on the Lt side as mentioned:
o adds 4 feet of fuel line between the firewall penetration and the engine mounted fuel pump.
o Apart from the added resistance and fuel flow loss, the proximity of the common exhaust pipe might induce fuel vapor lock despite heat sleeves or barriers to the gascolator.
o The cabin heat to the pilot, dumps hot air onto this position when the cabin heat source is closed.

60 hours, 1 annual and no down sides to report yet.
 
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I did the exact same installation as described below for the same reasons on my RV7A which has been flying since 2015 (300+ hrs). No problems to report. I would do it again (for mechanical fuel injection or carburetor) .The Andair gascolators are mostly for it filtering properties.

Bevan
Mechanical fuel injection (Precision)

This setup is fine for carbs or Bendix FI but the OP was asking about fuel systems for EFI.
 
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