Electric Remote Fuel Valve

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by TMann, Nov 7, 2019.

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  1. Nov 7, 2019 #1

    TMann

    TMann

    TMann

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    I'm looking for suggestions (i.e. Part#) for an electric fuel valve that I can stick in the back of my Velocity to avoid a long run of fuel lines forward and back.
    Andair has just introduced something that looks very promising but it's AN-6 & 28V.
    I would wait for a AN-8 12V if I knew it was coming.
    I don't need a duplex valve and a power off open default is a must.

    Anybody flying with such an arrangement?
     
  2. Nov 8, 2019 #2

    spaschke

    spaschke

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    you just gave me an idea on how to control my heat/defrost temperature. I have this an8 valve regulating the coolant going to the heater core, but I can't reach the valve while flying. I could use a servo. This could work for you also but not as elegant a solution as the Andair product.
    [​IMG] [​IMG][​IMG]
     
  3. Nov 8, 2019 #3

    TMann

    TMann

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    I did find this one which is 12v and NO (normally open) $103
    [​IMG]
     
  4. Nov 8, 2019 #4

    gtae07

    gtae07

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    Could you use a manual valve and a push/pull rod or something? Perhaps not the lightest option but maybe close to weight-neutral considering a run of fuel lines plus the fuel in them?
     
  5. Nov 8, 2019 #5

    TMann

    TMann

    TMann

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    The problem I'm running into is trying to find room within the tunnel to accommodate the fuel lines and valve.
    The tunnel stops at the bulkhead that makes up the back of the front seats.
    Inside that I have my control rods, hydraulic cylinder for the nose gear, etc.
    On the backside of that bulkhead I have what they are calling a "Whale Tail" that is connected to control cables for the Ailerons.
    On the floor is the long cylinder for the main gear.

    Bottom line..... lots of stuff to avoid.
    My initial plan was to setup a fuel valve up front with Left/Right/Both/Off selection options.
    I just can't find a route for the fuel lines that is going to work for me to make that happen.
    This has been a real show stopper for me and while I resisted for a long time now, I believe it is time to move on to option "B".
    Routing a cable or control rod would create another set of issues.
     
  6. Nov 8, 2019 #6

    Mad MAC

    Mad MAC

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    I would suggest that for ensuring system robustness the installed valve control should also indicate the valve postion in a manner that detects the actual valve postion, probably a couple of micro switches would do it. Making sure to avoid the 3 mile island scenario where the indicator just shows the postion of the switch.
     
  7. Nov 12, 2019 #7

    TMann

    TMann

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    I'm also looking at these valves.
     
  8. Nov 15, 2019 #8

    TMann

    TMann

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    Just about ready to pull the trigger on this. The valves are normally open and only close when power is applied. For that reason, I plan on having a battery backup in the event that I need to shutoff the fuel completely. I entertained the Idea of adding a mechanical valve of some sort but have ruled that out due to the added complexity involved in routing it.
    I also considered an additional valve beyond the two-into-one manifold and again ruled that out as being overly redundant (especially when you consider that this plane had zero fuel control previously, i.e. always on.)
    As far as installing some valve position sensor .... these valves are all enclosed so it's not like there is something by which you could trigger such with. About the only way you could detect the status of the valve would be to use a fuel flow indicator. That said, I'm looking for some LED switches that will illuminate a red triangle when the valve is powered (in the closed position.)
    I perceive that the only time I will be using these will be in the event of an uneven fuel flow from one tank or bad fuel in one side (both of which should be very remote.)
    A couple of notes about the fuel system design:
    There is a manifold that the vent lines run into which should allow the tanks to cross-vent to eliminate the likelihood of an uneven feed. It also offers a means to eliminate a possible siphon from being established.
    I have 5 one way valves in the system:
    • Two are inline between the tanks and the sump.
    • Two allow air out of the sump but not back in.
    • One allows cabin air into the vent manifold but not out into the cabin.
    The last one is to allow a vent to be established in the event that the two external vents become obstructed in some manner.
    There are two optical fuel level sensors (one for each half of the sump) which will illuminate a panel warning light in the event that you should ever get down to your last 5 gallons of fuel.

    NOTE: The drawing does not show the "Manual" fuel shutoff valves between the wing tank and the sump for maintenance purposes.
    FuelSystemDiagram.png
     
    Last edited: Nov 15, 2019
  9. Nov 19, 2019 #9

    TMann

    TMann

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    Well shoot, Solenoid Solutions, Inc sounded real promising but has a minimum order of 100 units.
    That's about 98 more than I need.
     
  10. Nov 20, 2019 #10

    Bill Welter

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    Tom, I'm using Hydraforce SV10-34-6T-V-12DS for my valve for return flow from the fuel rail, switches to dump fuel back to R or L tank. It has fuel-proof seals and uses -6 fittings, 12V. I got mine from Hydraulic Controls in Denver for $78 a few years ago.
     
  11. Nov 20, 2019 #11

    Russell

    Russell

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    TMann, have you looked at automotive valves? I have a left & a right tank that I switch with an electric fuel valve from an "80s GM Suburban. The valve has an output that indicates which tank is in use. Since I have a Subaru engine and return probably 70% of the pumped fuel back to the tank, this valve also switches the return fuel to the tank in use. I now have 820 hours on this valve. This may not be what you need but the automotive world makes many different types some may work for you.
     
  12. Nov 20, 2019 #12

    TMann

    TMann

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    @Bill I'll take a look at that. That might be a good option.

    @Russell - Yeah, I was looking at Summit Racing but wasn't having much luck.
    That is a good suggestion as well.

    Whatever I install, it has to be normally open, or open when the power is not present.
     
  13. Nov 20, 2019 #13

    Victor Bravo

    Victor Bravo

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    Still gives me the Willies, whether it's normally open or closed. Yeah, old-school, paranoid, Luddite. Guilty.
     
  14. Nov 20, 2019 #14

    BJC

    BJC

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    Me too, VB, me too.


    BJC
     
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  15. Nov 21, 2019 #15

    Mad MAC

    Mad MAC

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    Does one actually need a Left and Right fuel selector (unconventional but its just engineering). A pair of float valves in the centre tank can keep the wing tanks fuel even (technically wing level), although one does have to pay attention to the tank venting. Below is the fuel system diagram from the GA8 flight manual which uses such a system.

    Note that the critical feature is the outlet for the Port wing is on the Starboard side of the tank.

    GA8 FuelSystem.png
     
    Last edited: Nov 21, 2019
  16. Nov 21, 2019 #16

    TMann

    TMann

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    Well, if you could see what I have to work with, you would get it.
    The airplane has 85 hours on it with no fuel selector/shutoff what so ever.
    Most anything would be an improvement.

    By using a normally open solenoid valve, the only time power is applied is when you want to restrict fuel flow through the selected valve.
    I was very much against this approach initially but after seeing some of the flying examples I have had a change of heart.

    Actually, a left/right fuel selector has been pretty standard on every plane I've ever flown (Piper.)
    The main issue with this airplane consisted of an uneven fuel flow, which was a simple condition that could be corrected with a simple left/right fuel selector.
    The plane has a range of 1,100 NM which is great for that trip to the Bahamas, right. If one has to land in order to even out the fuel level, well it doesn't really have a range of 1,100 NM range now does it.

    Also consider this, if you were ever to have a missing fuel cap, a left right fuel selector will prevent the fuel from going overboard. I can explain if you can't visualize that.

    My first choice was to use a left/right/both/off manual valve but given the setup (Velocity) there is no way that I have found to run the lines forward and back while clearing the hydraulics and control rods, etc.
    So given I am working with something that was previously built by someone else, I am merely try to make the best of a bad situation.

    The design is not going to change. The only variables that exist would be restricted to the specific solenoid valve will be used.
     
  17. Nov 21, 2019 #17

    wsimpso1

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    You are proposing to use normally open electrically powered flow valves for tank trim. Leaving them normally open would seem to leave you with fuel no matter what happens to electrical power for them. The failure mode of "Fails Closed" is one I would be concerned about, and would want to assure myself is REALLY unlikely by design. In order to facilitate low orders of probability on "Fails Closed", a design that does hard seal when closed may be chosen, which then begs the question of "how to shut off fuel in an engine fire?" Actuation of the shutoff valves would have to remain alive in a case where you will likely be cutting off master switches, making fuel cutoff dependent upon backup power that may get short shrift when hardly ever used.

    I suspect that a manually powered shutoff would be important. A simple handle pulling a cable on a ball valve as shown in post #2 would be a big help with an engine fire. You could even secure it with 0.020 brass safety wire as a safeguard against inadvertent actuation.

    Billski
     
  18. Nov 21, 2019 #18

    TMann

    TMann

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    Exactly. These are "Fail Open" valves.
    The power is supplied via a backup battery that is independent of the Master. Same for the electronic ignition.
    Agreed, and I see that happening just aft of the two-into-one manifold.
    Much like the fuel flow, that is downstream. I won't need a manual shutoff if I can't locate a viable solenoid valve.
     
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  19. Nov 21, 2019 #19

    Victor Bravo

    Victor Bravo

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    But then "Fail Open" prevents you from shutting off the fuel (in some sort of catastrophic engine fire, where your alternator or battery or wiring has been consumed by fire and not working).

    I'm fully aware that many large transport and corporate airplanes are 100% electrically dependent, and do not have mechanical control backups. In some cases you just can't possibly run a push-pull tube or a set of cables all the way out to the engines or fuel tanks on a C-5 or SR-71. You're stuck with wires and actuators on stuff like that.

    But anywhere you can reasonably run a mechanical control to shut off the fuel supply, on a small GA sport personal aircraft, I'd say go to that extra effort. For Grandma and the kids, even if you're sure you'll never need it.

    So, putting my small brain where my big mouth is... what about a small diameter Bowden cable that pulls the valve open or closed against a return spring? You can accomplish this with less than 1/4" OD, floxed into an inside corner of in your tunnel structure. The "spiral wound wire" on the outside and steel wire on the inside, this stuff is used in many places on airplanes... cowl flaps, carburetor heat,etc. It is moderately flexible, and can even be used as a push-pull control in low-strength applications. It will withstand heat, and in an emergency you can pull on that wire with many hundreds of pounds of force to shut the fuel off.
     
  20. Nov 21, 2019 #20

    Russell

    Russell

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    The fuel valve that I use is held in position with a screw type actuator … not a solenoid. The valve normally has no power applied. Power is only applied for the 1/2 second that you command a tank change. If power is lost the valve remains in the last commanded position. This type valve ends worries about a solenoid valve needing power to keep the fuel tank closed in the event of an emergency.
     

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