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SDS Fuel filter mounting location ideas

Jcohen

Member
I am building an RV7 with SDS EFII. I would like to mount my larger fuel filter (upstream of the dual fuel pump) in the area between the wing root and fuselage skin (one in each wing) as the fuel supply line exits the tank. But I do not see a good secure mounting method for the filter in this area. I don’t think cantilevering it to the wing skin is a good idea. Or is it?

Does anyone have any pics to share or ideas on how they mounted their SDS system fuel filters?

Jeff
 
You could bury them under the seat pans behind the sticks; on each side or on the floor close, and parallel tto the spar...
 
There's a couple pictures of wing root mounted filters on Ross's website. The pictures are of an RV8, but the RV7 should be similar.
 
I looked at the wing root but decided it was a little tight quarters, I put mine on the forward face of the wing spar, easy to access for cleaning during annual.
 
Jeff, we've done quite a few root filter kits for the RV14, RV10 and now working on a modified version for the RV7/8s, both with and without inverted fuel pickups in the nose of the tanks . Several prototypes in beta testing now.

Tom
 
I looked at the wing root but decided it was a little tight quarters, I put mine on the forward face of the wing spar, easy to access for cleaning during annual.

Greg's point is a good one - you want easy access to these filters both to ensure that they are not leaking, and to clean them regularly. Particularly during the first few tanks of fuel you run through them.

My wing root fairing was hard to get on and off the first few times, but now that the rubber seal is "broken in", it's very easy and fast with a screw gun.

I think this is an excellent place for a filter.
 
I am building an RV7 with SDS EFII. I would like to mount my larger fuel filter (upstream of the dual fuel pump) in the area between the wing root and fuselage skin (one in each wing) as the fuel supply line exits the tank. But I do not see a good secure mounting method for the filter in this area. I don’t think cantilevering it to the wing skin is a good idea. Or is it?

Does anyone have any pics to share or ideas on how they mounted their SDS system fuel filters?

Jeff

Here is one I grabbed off something somewhere Jeff


52431890042_fdbb38b67a_h.jpg
[/url]wing root fuel filter2 by Kent Luttrell, on Flickr[/IMG]
 
You speak nicely to Mr S.... He will make you some exquisite fuel lines and filters for an exorbitant price that is well worth it.....;):D
 
I really, really don't like those 90-degree turns on the suction line from the fuel tank. If you're going to burn 100LL all your life, it will work fine. If you want to run autofuel you will have issues with vapor pressure and producing bubbles at those 90's in hot temperatures. I used a longer piece of flexible hose from Tom Swearingen that I put in wing root, but avoided all the 90's for that reason.

If you want to run autofuel - ANY possible pressure drop or restriction between the tank pickup and the fuel pump is to be avoided, where possible. I run straight lines, no 90's, and large prefilters with lots of filter area for low pressure drop.
 
I really don't like those 90-degree turns on the suction line from the fuel tank. If you're going to burn 100LL all your life, it will work fine. If you want to run autofuel you will have issues with vapor pressure and producing bubbles at those 90's in hot temperatures. I used a longer piece of flexible hose from Tom Swearingen that I put in wing root, and avoided all the 90's for that reason.

If you want to run autofuel - ANY possible pressure drop or restriction between the tank pickup and the fuel pump is to be avoided, where possible. I run straight lines, no 90's, and large prefilters with lots of filter area for low pressure drop.

The biggest hurdle in outfitting an airplane to run 91E10 is not the engine, by a long shot. It's learning how to build a hydraulically correct fuel system.
 
I looked at the wing root but decided it was a little tight quarters, I put mine on the forward face of the wing spar, easy to access for cleaning during annual.

Greg, do you have any pics? How did you secure your filters to the forward face of the wing spar? Or do you mean main spar in the cabin? Thanks for your help.
 
To follow best practice, we don't like to see drilled 90 deg fittings prior to the pumps as Greg said. If you must, it's preferable to use the mandrel bent tubing type ones.
 
Question, not a criticism

Post #9.

Pardon, but from my old-a$$ eyes, in pic 2 the filter appears to be only supported via the fluid connections. I'm not versed enough in the related regs but this would certainly seem to violate good shop/design practice at least. Can anyone state a known valid position on such? Thx.
 
If you want to run autofuel you will have issues with vapor pressure and producing bubbles at those 90's in hot temperatures

Is this is something that is generally well known? What would be a good reading regarding these kind of issues in fuel supply designs?
 
@ Larco

I'm a pretty experienced engineer as well. There is little doubt in my mind that the associated static loads are of little concern. That said, there is a mass supported only by fluid fittings/connections, fixed support by tubes that have elasticity. Even if assuming perfect workmanship (flaring material thickness, no torsion load from torqueing, no preload other induced, etc.) it is a classic example of spring/mass system that will experience cyclic loading. Everything is good until it suddenly isn't.

My intentions here are good. I said it was a question, not a criticism. Most codes and standards leave room to deviate if the proper calcs and/or validation is done. This is beyond the will, if not skills, of most techs/inspectors/engineers. So now back to my question.

Are there regs (in any form, ACs, etc) that specify or advise on such installations?

If the weight of the tube itself is cause enough for unsupported length maximums, this only makes sense.

Anyone?
 
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I'm not an engineer but think similarly to Freemasm here. I feel best practice is to support the major mass with an Adel clamp. To that end, our filter kits supply a single clamp for the small filters and twin clamps for the larger one.

There are close quarters here and not easy to get big hands in here to work. The small filters are pretty light and vibration here pretty low so support outside the filter may work just fine. The proof will be in the pudding at a couple thousand hours...
 
Is this is something that is generally well known? What would be a good reading regarding these kind of issues in fuel supply designs?

I summed things up a couple weeks ago with a post in another thread:

Best practice for those considering EFI and mogas use in RVs:

Pump placement should be on the floor, not FWF

No drilled 90 deg fittings prior to the pumps, mandrel bent 90s are acceptable

90s are ok downstream of the pumps

-6 line for all plumbing

Return fuel from the regulator should go back to the tanks, never back to pump inlet

Never use winter formulation gas in the summer (colder climates where it's different). Drain out that old fuel if in doubt

Good idea to buy a Peterson/ Hodges Fuel Volatility Tester, especially as the seasonal changes in fuel formulations occur in winter/ spring/ summer in cooler climates
 
Greg, do you have any pics? How did you secure your filters to the forward face of the wing spar? Or do you mean main spar in the cabin? Thanks for your help.

Where the main spar comes through the cabin, on the forward side. There are already a couple small braces there where you drill holes and place grommets for the fuel line passthru, I added one for additional support and set the filter between them so the grommets support the resonant mass load.

Is this is something that is generally well known? What would be a good reading regarding these kind of issues in fuel supply designs?

No, unfortunately. Knowledge in this area is abysmally rare. It's one of the reasons I keep preaching it. Good knowledge for a proper, hydraulically correct fuel system design is going to require a background in chemistry and ideally some physics.
 
I summed things up a couple weeks ago with a post in another thread:

Best practice for those considering EFI and mogas use in RVs:

Pump placement should be on the floor, not FWF

No drilled 90 deg fittings prior to the pumps, mandrel bent 90s are acceptable

90s are ok downstream of the pumps

-6 line for all plumbing

Return fuel from the regulator should go back to the tanks, never back to pump inlet

Never use winter formulation gas in the summer (colder climates where it's different). Drain out that old fuel if in doubt

Good idea to buy a Peterson/ Hodges Fuel Volatility Tester, especially as the seasonal changes in fuel formulations occur in winter/ spring/ summer in cooler climates

Thanks Ross, a good list of guidelines, IMO.
 
@ Larco

I'm a pretty experienced engineer as well. There is little doubt in my mind that the associated static loads are of little concern. That said, there is a mass supported only by fluid fittings/connections, fixed support by tubes that have elasticity. Even if assuming perfect workmanship (flaring material thickness, no torsion load from torqueing, no preload other induced, etc.) it is a classic example of spring/mass system that will experience cyclic loading. Everything is good until it suddenly isn't.

My intentions here are good. I said it was a question, not a criticism. Most codes and standards leave room to deviate if the proper calcs and/or validation is done. This is beyond the will, if not skills, of most techs/inspectors/engineers. So now back to my question.

Are there regs (in any form, ACs, etc) that specify or advise on such installations?

If the weight of the tube itself is cause enough for unsupported length maximums, this only makes sense.

Anyone?

I agree. A spring mass system, with cantilevered supports consisting of only the aluminum tubing, is subject to cycling loading, leaks, and fatigue failures. The filters with fuel have significant mass subject to aircraft accelerations (G-forces), right? I am striving to support each filter using the Adel clamps provided by Ross in the SDS kit.
 
Where the main spar comes through the cabin, on the forward side. There are already a couple small braces there where you drill holes and place grommets for the fuel line passthru, I added one for additional support and set the filter between them so the grommets support the resonant mass load.



No, unfortunately. Knowledge in this area is abysmally rare. It's one of the reasons I keep preaching it. Good knowledge for a proper, hydraulically correct fuel system design is going to require a background in chemistry and ideally some physics.


Greg, I like your idea of mounting the large upstream filters inside the cabin on the forward side of the main spar. I will look at how to do that, although I am reluctant to drill into that main spar to mount another brace without guidance from Vans. If you have any sketches or guidance or pics I would appreciate any help.
 
Thanks for this discussion and for all of your comments so far. I am excited about getting my SDS EFII working. Routing and packaging the dual fuel pump, fuel lines, and filters, and Andair valve is something I feel is safety critical, yet I don’t feel comfortable with the implementation examples being so open ended. I am looking for best practices from those that have gone before me with lessons learned.

Maybe it’s just me, Ok with being on the leading edge sometimes, but never on the “bleeding edge”!
 
If your not dead set on running individual tank filters, you can do a pre/post pump filter setup like this and cover it up using the standard fuel injection pump cover from Vans.
 

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If your not dead set on running individual tank filters, you can do a pre/post pump filter setup like this and cover it up using the standard fuel injection pump cover from Vans.

Hmmm, nice packaging there, well done.
 
Yes, very nice

"Bought everything straight from SDS. TSflightlines even has a kit for the required fuel lines in this setup."

Those are the 100 and 175 GPH filters? The 175 is the prefilter? What micron ratings are you using?

Thanks
 
If your not dead set on running individual tank filters, you can do a pre/post pump filter setup like this and cover it up using the standard fuel injection pump cover from Vans.

Looks good! How did you secure the filters? Using adel clamps attached to what, each pump motor with another clamp? And are these the SDS supplied filters? Mine look different. Do you have any more pics?
 
For the smaller filter downstream of the pump, I might mount it on the lower firewall, around where the rv7 plans call for old facet style elec fuel pump, but anyone see any concerns if I mount it on the engine side vs the cabin side? Seems to me that is safer, but Maybe I am overlooking something? Comments?
 
For the smaller filter downstream of the pump, I might mount it on the lower firewall, around where the rv7 plans call for old facet style elec fuel pump, but anyone see any concerns if I mount it on the engine side vs the cabin side? Seems to me that is safer, but Maybe I am overlooking something? Comments?

Heat load, if you ever want to run autofuel.
 
For the smaller filter downstream of the pump, I might mount it on the lower firewall, around where the rv7 plans call for old facet style elec fuel pump, but anyone see any concerns if I mount it on the engine side vs the cabin side? Seems to me that is safer, but Maybe I am overlooking something? Comments?

My smaller filter is mounted FWF. I run 93 octane ethanol free fuel with no issues (at least not since I started flying 60 hrs ago). I wish I had done a small filter in each wing root now. Perhaps a future upgrade.
 
"Bought everything straight from SDS. TSflightlines even has a kit for the required fuel lines in this setup."

Those are the 100 and 175 GPH filters? The 175 is the prefilter? What micron ratings are you using?

Thanks

I believe you are correct on the filter sizes. The 175 is the pre-filter since it operates under suction instead of pressure. Ross from SDS recommended 40 micron for both pre and post filters. My other vehicle that ran a similar pump setup like this, I normally ran 100 pre, 10 post. Holly only sells 40 micron filters for carb'd applications, so I went with the 100/10 setup that was rated for EFI from Holly. I don't think you'd have a problem with the 40 micron "carb" filters from holly being able to handle the 40 psi system pressure for the SDS though if you wanted to go with them instead.


Looks good! How did you secure the filters? Using adel clamps attached to what, each pump motor with another clamp? And are these the SDS supplied filters? Mine look different. Do you have any more pics?

There is an adel clamp around each filter, and one adel clamp around one of the pumps. You 3-way them together. With the single adel clamp, plus the hard line on each end, there isn't much room for vibration. These were the filters that came supplied from Aerosport with the engine. Holly also makes an assortment of round fuel injection filters that you can use as replacement (https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/filters/efi_filters/).


For the smaller filter downstream of the pump, I might mount it on the lower firewall, around where the rv7 plans call for old facet style elec fuel pump, but anyone see any concerns if I mount it on the engine side vs the cabin side? Seems to me that is safer, but Maybe I am overlooking something? Comments?

Ross would be the best guy to answer this, but with the amount of return fuel flow that SDS runs, I don't think heat soaking will be an issue. Just run the pump for an extra 5 seconds before a hot start and all the hot fuel in the lines and filters gest flushed back to the tank.

Things I learned when doing this:
1. The black NPT plugs in the pump frame must be removed, pipe sealant added, and then reinstalled. I'm almost positive the SDS guide mentions this and yet I still forgot. I had a nice fuel leak during phase 1 that took me a minute to track down.

2. The TS flightline return hose has to be measured based on where you install the fuel return nipple. I attached the pic that tome sent me, plus a pic of my wing on where I put the return fitting. I think the hose length difference was about an inch.

For power, I ran a 4 wire Deutsch DT/DTM knockoff connector. This let me have a single point disconnect for when I had to remove it but still provides each pump individually fused +12 sources.
 

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