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planes_by_ken(at)bellsout
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 Posted: Thu May 25, 2006 4:30 am Post subject: Cortec 373 and airframe ground continuity |
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Rory Davis wrote:
| Quote: |
Has anyone using Cortec 373 primer had any problems with high airframe ground
resistance or intermittent grounding?
Cortec being a plastic (insulator), doesn't it electrically isolate each side of
the metal joint if applied between the two halves, with ground continuity
relying on the rivets and scratches/imperfections in the primer?
I'm getting ready to close up the first wing on my 701 kit and in the process of
installing the strobe box and fuel tank grounding got to thinking about this. I
scraped away the layer of primer at the grounding points but then realized all
the ribs and channels may be electrically isolated from each other. This could
make for noisy radio comms or odd electrical faults in the future.
Any comments?
Rory
Lacombe, LA
CH701 Working on wings
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Also, an anodized surface is high resistance. I don't know about
alodine. Allot of airframes are bonded (glued sheet metal)
construction. I wonder if they have any problems.
Ken Lilja
601XL rudder done.
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gfmjr_20(at)hotmail.com
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| Posted: Thu May 25, 2006 3:42 pm Post subject: Cortec 373 and airframe ground continuity |
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Ken--
I used cortec throughout, however, I cleaned all electrical contact area.
I'm running an all electrical panel using Dynon EFIS and Dynon FlightDeck
along with autopilot, com ,nav, and transponder and have had no problems so
far in my electrical checkout. No noise on radio and the Dynons are working
ok so far.
George May
601XL 912s
| Quote: | From: Ken Lilja <planes_by_ken(at)bellsouth.net>
Reply-To: zenith-list(at)matronics.com
To: zenith-list(at)matronics.com
Subject: Re: Cortec 373 and airframe ground continuity
Date: Thu, 25 May 2006 08:29:09 -0400
Rory Davis wrote:
>
>
> Has anyone using Cortec 373 primer had any problems with high airframe
ground
> resistance or intermittent grounding?
>
> Cortec being a plastic (insulator), doesn't it electrically isolate each
side of
> the metal joint if applied between the two halves, with ground
continuity
> relying on the rivets and scratches/imperfections in the primer?
>
> I'm getting ready to close up the first wing on my 701 kit and in the
process of
> installing the strobe box and fuel tank grounding got to thinking about
this. I
> scraped away the layer of primer at the grounding points but then
realized all
> the ribs and channels may be electrically isolated from each other. This
could
> make for noisy radio comms or odd electrical faults in the future.
>
> Any comments?
>
> Rory
> Lacombe, LA
> CH701 Working on wings
Also, an anodized surface is high resistance. I don't know about
alodine. Allot of airframes are bonded (glued sheet metal)
construction. I wonder if they have any problems.
Ken Lilja
601XL rudder done.
|
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steveadams
Joined: 10 Jan 2006
Posts: 191
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| Posted: Fri May 26, 2006 3:25 am Post subject: Re: Cortec 373 and airframe ground continuity |
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You will want to remove the primer and have bare metal wherever you connect a ground directly to the airframe, but I wouldn't worry about lack of continuity at the joints due to the primer. Even with some resistance due to the primer, there is such a huge surface area that I don't think it is an issue with the currents we are talking about. I am no expert, so you may want to search the aeroelectric list to see what they have said about it.
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p.mulwitz(at)worldnet.att
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| Posted: Fri May 26, 2006 4:13 am Post subject: Cortec 373 and airframe ground continuity |
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I think insulation in the joints could ruin the ground provided by
the airframe. Even though there is a lot of good conductor between
the joints something close to complete circuit isolation could take
place at the joints. If this happens there will be no ground
connection at all for the remote circuits.
The biggest problem (besides complete circuit failure) I would expect
would be interference with radio clarity generated by the strobes.
Fortunately, it is relatively easy to measure the impact of joint
isolation. Just measure the resistance from one end of the plane to
the other with a multimeter. I would be concerned with anything
over 100 milliohms. If the resistance is large the solution would be
to run separate ground wires from the remote devices to the battery
or common ground point.
Paul
XL wings
recovering circuit designer
At 04:25 AM 5/26/2006, you wrote:
| Quote: | You will want to remove the primer and have bare metal wherever you
connect a ground directly to the airframe, but I wouldn't worry
about lack of continuity at the joints due to the primer. Even with
some resistance due to the primer, there is such a huge surface area
that I don't think it is an issue with the currents we are talking
about. I am no expert, so you may want to search the aeroelectric
list to see what they have said about it.
|
-
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dredmoody(at)cox.net
Guest
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| Posted: Fri May 26, 2006 5:47 am Post subject: Cortec 373 and airframe ground continuity |
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The rivets should provide enough electrical continuity through the joints.
Ed Moody II
Rayne, LA
601XL / wings
Subject: Re: Cortec 373 and airframe ground continuity
| Quote: |
You will want to remove the primer and have bare metal wherever you
connect a ground directly to the airframe, but I wouldn't worry about lack
of continuity at the joints due to the primer. Even with some resistance
due to the primer, there is such a huge surface area that I don't think it
is an issue with the currents we are talking about.
|
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