Fuel tank grounding

[jonbakerok]

There was an old thread on Matronics about fuel tank grounding. It sounds like a good idea so I'm trying to figure out how to do it.

Anybody know how to get the filler lip hot enough to solder without ruining the fiberglass it's attached to?

[DanB]

Jon,
Interesting thought and probably worthwhile doing. I would take a look at a conductive epoxy.

[HighWing]

Jon,

Your post is timely. I am prepping my second wing for covering and grounding the filler neck would have slipped beneath the radar this time as it has been a year since the first wing was finished. Thanks for the reminder. I grounded my first wing by using some of the copper adhesive backed tape that the stained glass folks use. It is 1/4 inch wide and a bit thicker than common masking tape. I stripped the adhesinve from a lenght long enough to go around the neck. Then soldered a loop to a tight fit around the neck and using some conductive adhesive glued it in place. The copper ribbon was then traced across the short edge of the tank, down and arounjd and then to a brass screw through the aft web of rib #1 on the fuselage side with a double nut for the pigtail to the fuselage.

my first 900 hour model IV was not grounded. I have read that wiping the top of the wing with damp rag will dissapate static electricity that has accummulatede there. Then again, I didn't do that very often. But this time it will be grounded.

Lowell

[jonbakerok]

I really liked the conductive adhesive and copper tape idea.

But I just had an experience that caused me some concern.

After I cleaned and dried my tanks, I taped the filler neck closed with some aluminum tape. That turned out to be a very bad idea. When I removed the tape to study this grounding issue, I discovered that whatever residual humidity was left in the tank had caused some pretty bad galvanic corrosion (rust!) between the aluminum tape and the steel filler neck. The adhesive seems to have even made it worse. The tape was only on there about 3 months, but by that time I'd installed the tanks in the wings and it was a mess to clean up.

So now I'm concerned about gluing copper tape to the steel filler necks.

[RobS]

The following web site has information regarding "galvanic corrosion" and the acceptable difference in the "anodic index" of dissimilar metals. The information there states that in a harsh/outdoor environment, anything above a 0.15v difference could be problematic. If the filler neck is stainless, the difference between it and copper would be 0.15v. If the neck is made of plain carbon or low alloy steel it would be 0.50v.

http://www.engineersedge.com/galvanic_capatability.htm

[SkyPirate]

you can use dialythic grease between any unlike conductive materials,..the same grease used for electrical component heat sinks,..just make sure you cover the entire surface of the contact areas and then apply a little around the edges to ensure minimal exposiure to elements and air,..

Chase