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Thread: Capacitive Fuel Adapters

  1. #1

    Capacitive Fuel Adapters

    Does the AF EFIS systems work ok with capactive fuel senders? Are there specific adapters that are needed? I've read that there is a Dynon one, but I also see Vans selling one now for less - http://www.vansaircraft.com/cgi-bin/...t=ei-fuelgauge. Will these (IE P-300C) work with the AFS setup?

  2. #2
    Yes it sure does! We have many customers with capacitive fuel senders. We just need to know ahead of time so we can cut a few jumpers internally on the EFIS engine board. Adapters are required and we recommend either the Dynon adapter or one we sell. They are $165/ea and you'd need two.
    ---
    Trevor Conroy
    Technical Support
    Advanced Flight Systems
    Support@Advanced-Flight-Systems.com

  3. #3
    I did not specify capacitance fuel probed when I ordered my AF 3400. Does it need to go back for mod in order to use the capacitance sender? Or can I use the Dynon capacitance converters without the need for a mod. RV-8 is complete so I cannot refit w/ float senders.

  4. #4
    Advanced Flight Systems Shawn McGinnis's Avatar
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    You will need to cut the jumper for the AF-3400 to be able to read the cap level adapters. I have sent you an e-mail that explains the process. Alternatively, if you want to have us cut the jumper its not a problem.
    Shawn McGinnis

    Advanced Flight Systems
    support@advanced-flight-systems.com

  5. #5
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    Shawn, I have a pair of 4500's and if I remember correctly, I think that I specified that I would be using cap fuel senders, but I am not sure. Could you please send me a copy of the procedure referenced above so that I can check my 4500.

  6. #6
    Check the current AD value in the Tank calibration menu. With nothing connected to the tank sensor wire it will be almost zero if configured for capacitance tanks. If it is configured for floats it will be around 1800.
    Rob Hickman
    Advanced Flight Systems Inc.

  7. #7
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    Trying to diagnose new problems with my Westach gauges, which worked fine for over 160 hrs. Is the zero figure given above meant to be with power and ground connected to the gauge sender, just not sensor wire, or with everything disconnected from gauge sender? (I have AD_value 3600 in the latter case.)
    Ron
    Murphy Rebel / Jabiru 3300A
    Dual AF-3400s (EF/EE+AOA)
    http://n254mr.com

  8. #8
    The number should be close to zero with the wire disconnected from the EFIS, if the EFIS is setup for voltage input on the fuel gauges. Normally you can’t connect two gauges to the same probe.

    Some of the Westburg probes were setup to output a resistance and act like a standard float sending unit. You need to figure out what you have and how it works.
    Rob Hickman
    Advanced Flight Systems Inc.

  9. #9
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    According to the invoice sent to the orig. builder, I have Westberg 395-5SB5 senders, which are described as "Capacitance Fuel Level Sender...240 ohm, 12VDC." (I've left out a couple physical size refs.) These have worked fine for >160 hrs, with a 1.5K ohm resistor in the 12V supply line, as instructed back in '08. (I note the current schematic shows the resistor in the EFIS sense wire. If that's significant, it didn't affect performance before now.)

    The left one now reads anywhere from 0.0 -- 3.x gal., with actual 10-11 gal. in the tank, and, even more oddly, the right one, which was fine for ~3 hrs. after the tank repairs (see below) suddenly failed to 0.0 in flight attitude (it's a taildragger) but then recovered on the ground. On the next short leg, it failed again in flight attitude, but recovered on the ground again. Pretty strange, but at least it's reproducible. (Calibrations have not changed.) Any guesses on possible failure modes for that?

    Since things worked fine, the tanks did undergo significant repairs for seepage issues and, though the senders were not removed, it's possible one or both got nudged somehow. It would be odd that both would fail from something like that and the original builder secured the bottoms of the tubes slightly above their ends in a small "stalagmite" of ProSeal -- so they're not waving around loose. Prior to reassembly there was no evidence of undesirable tank contact (confirmed even now via borescope) or other damage and the symptoms Westberg describes for undesirable tank contact or concentric tube contact are also not present.

    At this point I doubt this is an EFIS/EIS issue -- though the flight/ground attitude thing is strange -- but the problems remain difficult to diagnose. If anyone has suggestions, or is otherwise willing to participate in the hunt, I have measured a set of electrical datapoints in various states. There are no shorts, power failures, or other apparent clues. I haven't yet tried recalibrating because it seems like a long shot, but probably will. Replacing the senders is doable, of course, but would be quite difficult, to say the least.
    Last edited by rshannon; 02-11-2013 at 06:02 PM.
    Ron
    Murphy Rebel / Jabiru 3300A
    Dual AF-3400s (EF/EE+AOA)
    http://n254mr.com

  10. #10
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    Hmm. With jumpers, I tried swapping the senders from their normal EFIS tank circuit to the opposite EFIS tank circuit, one at a time. I'm getting very different results -- still erroneous -- when they're swapped to the other tank circuit. It seems that if the problem is just in the sender(s) they should exhibit the same behavior regardless of which tank circuit they're on, but that's not the case.

    I will carefully re-check the resistor values and the EFIS Engine Sensor plug for integrity, continuity, etc., and if they still look OK, I probably should send this unit back for a checkup, just to cover all the bases before deciding on surgery for the senders.
    Ron
    Murphy Rebel / Jabiru 3300A
    Dual AF-3400s (EF/EE+AOA)
    http://n254mr.com

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