>
    >           Paul,
    >      FWIW: To help narrow down your options:  I believe my
   Lancair ES has
    > the
    >      same EI fuel probes as yours, but mine are connected to a
   standard
    >      EI fuel
    >      gage.  I have no problems with wandering indications in flight.
    >
    >      Composite wings do generate static charges in
   flight--especially in
    >      light
    >      rain.  I flew through a very light rain shower enroute to
   Oshkosh in
    >      2003.
    >      The electric trim position indicators went absolutely wild,
   flashing
    > all
    >      kinds of lights, and then went blank.  The trim motors still
   worked,
    >      and the
    >      EI fuel gage indications remained steady.
    >
    >      Tom Parkes
    >
    >
    >
    > Tom,
    > Are your gauges affected by the nav/com?
    >
    > Mark
    >
    >
    > Not that I recall.  I hope to give an update on this before the
   end of
    > March.
    >
    > Tom


   Could the pressure increase inside the tank going up with speed
   via the venting cause a capacitance variation thus a different DC
   reading.

   It could be verified on the ground by increasing lightly the
   pressure in the
   tank.
   Or in flight taking a reading in slow flight and another one at cruising
   speed.

   Just guessing have no logical explanation for such a phenomena.

   JP



JP,
I paid close attention to the fuel level readings on my last flight and
I have to say that they appeared to be pretty steady in level flight.  I
may have caused some of the change in readings via uncoordinated turns.
Not that the ball was all the way left or right, but just a little,
possibly enough to cause the fuel inside the capacitive probes to move
up the tube a bit, which would cause the fuel readings to vary a bit.

The big surprise was when the right gauge, the one with the Dynon CTV
converter installed, went to zero as soon as I keyed the mic.  Up to
that point, it had been the more reliable of the two.  I'll have to
check again, but the left gauge, the one with the stock EI circuitry
(square wave a/c) appeared to drop by a few gallons while the mic was
keyed.  An undesirable feature, but not as drastic as the right side.

I plan on doing the following:
1)  re-route the antenna cable away from the efis and other wiring
2)  mount the CTV in a grounded metal box
3)  run a separate ground from the capacitive probe to the a/c ground bus
4)  Purchase an EI fuel gauge and hook them up and forget about reading
fuel levels on the EFIS.  ;-)

Mark S.

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