LML Gang,

I want to take a moment and follow up to my post of last week regarding apparent failure of my VisionMicro fuel probe and thank several of you who followed up with me.

The bottom line is that the head of the probe, which contains some amplification electronics powered by +5VDC, had some moisture in it and was shorting out some portion(s) of the signal.  I got it dried out and am back in business.

I spent some time with Dave at VisionMicro to figure out how to get the moisture out.  What we ended up doing was removing one of the 3 screws from the head of the probe, warming the probe (removed from fuel tank) head, and letting it "breathe" through the hole from the screw.  When removing the screw be VERY careful.  DO NOT remove the center one -- it holds the center conductor (plate) of the capacitive probe.  Dave says you can remove only one of the two other screws as they hold the electronics in place inside the probe.  If you remove both you will lose the electronics.

Another key learning for me was that these probes are NOT to be exposed to the elements.  Well, by design on the 320/360, the heads of the probes are exposed to the elements through the wing joint as well as the wheel well.  Dave said he did not know that we Lancair drivers had this type of setup and we should not be surprised if we have these kind of problems.

A solution advocated by one of our Lancair builders is to seal with silicone where the wires enter the head of the probe as well as where the wires enter the exposed heatshrink coming out of the probe.  I ran this by Dave and he thought it would be sufficient but prefers that we enclose the head in some airframe structure.  At this point, I have used the silicone method.

Thanks to all who chimed in to help me out.  I thought I was going to have to remove the wing to get the probe all the way out -- and miss the Redmond fly-in.

Dan Olsen