M

mlwynn

Well Known Member
Hi all,

I am planning to ground my landing lights, nav lights, and strobe using as frame ground as discussed in this thread:
http://www.vansairforce.com/community/showthread.php?t=7077&highlight=electrical+ground

I was thinking about how to best make the frame ground at the wingtip and was planning to use a 3/16 brass bolt. I had planned to drill a hole in the spar web, insert the bolt and use it as a common grounding point. I am reluctant to use a rib as I have primed them all and doubt there is a reliable electrical connection from there to the rest of the spar.

Does anyone anticipate a corrosion issue or conduction issue with this setup?

Regards,

Michael Wynn
RV 8 Wings
 
I grounded to the spar in a similar fashion using a CR Steel bolt and aluminum washer according to AC43.13. I coated the whole ground point in dielectric grease.

I don't think a brass bolt has any advantages, and AC43.13 does not cover it's use on an aluminum substrate.

BTW, I checked with Van's before drilling a hole in the spar web near the outboard edge... no problem.

Vern Little
 
Spar web or end rib

I debated this in my head for a while also. I eventually went with a nutplate for a AN3 bolt on the end nose rib. I primed also, but sratched it off in an area the size of the washer I will be using. I will also use an electrical joint compound when connecting them.

I got out my trusty multimeter and did some tests first. Apparently the anodized conversion on the aluminum spar surface does not conduct electricity very well, but anywhere the anodized layer has been removed, such as in a drilled hole, the resistance was very low. Drilling a hole in the spar web was not a problem for me, but trying to neatly remove the anodized layer for electricl contact with a washer was. So, I opted for the rib. The path to ground is through the rivets, and there are many of them.

Don't take my word for it though. Get a multimeter and test yours to ensure your bonding point really will get to ground.
 
Answering my own question

I searched a little better and discovered that AC 41-13-1B covers this very neatly. See this thread:

http://www.vansairforce.com/community/showthread.php?t=7077

I think I am going to go with a bolt and aluminum washers. Dielectric grease is found at Radio shack or similar? Seems like I remember it from seating electronic componets.

I have not figured out how to scrap off the anodizing in a perfectly round little spot for the aluminum washer.

Thanks

Michael Wynn
RV 8 Wings
 
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