RTV sealant question?

I am about to install and finish up the rudder components etc... but before I rivet it all up the instructions say to add a dab of RTV to the stiffeners. So my question is.... What kind? I see menards carrys RTV sealant but of course they have 3 different versions Black, blue, high temp? Menards list

I am assuming that getting the black one will work since it isnt a temperature sensative area of course.

Thanks, I would love to get this rudder done ASAP, so I can get the elevators started.... must get done before I leave for college in late August!

i used

Ge brand specific for aluminum. Its silver color but the important thing is its low.or no acetic acid (based on smell) to preclude corrosion. Used this several places around the plane...

Permatex Ultra Grey sticks to aluminum like hot bubblegum on your shoes (it's made especially for small aluminum engine valve covers, oil pans etc) and dries slightly more stiff, less rubbery than other RTVs. Kinda like the consistency of well-cured proseal.

Use Dow corning mill spec 3145 RTV if you epoxy primed inside.

Electronics grade

Any good electronics store, (Not RadioShack) will have a non-acetic acid based silicone sealant. It takes a little longer to set but there is no chance of reaction with the aluminum. I use GC (not GE) Electronics Grade Sealant/Adhesive.
I was told early in my build that it wasn't wise to bury standard Home Depot grade silicon adhesive in the plane since the acedic acid in the sealant will react over time with any aluminum. It didn't cost anymore than the regular stuff and I figured it would be better to be safe than end up with a hole in my plane. Not pretending to be a chemist here but the advice I received long ago stuck for some reason. I must have respected the person who told me. I'm open for correction if we have any real Chemists here in the VAF.

Now I finally have a chance to read these responses.... And now I feel incorrect for going to an auto store and finding and buying the red one that is linked in this forum!

Should I return it or is it more of a it'll work type thing!

The red hi-temp silicone (with acetic acid) is still very useful for lots of things under the cowl... sealing air leaks in the baffling, supporting wires and SCAT tubes, etc. Any perceived corrosion hazard from the acetic acid is usually not really much of a concern there.

Anyway, the Permatex "Ultra" series of RTVs do not have acetic acid in them, they're aerobic, oxime-based RTVs, and stick to aluminum very well. They are non-corrosive and approved for electronics, and as such, should also not present any corrosion hazard to aluminum either.

Copied from my builder's manual -

"Permatex UltraBlue, p/n 77B, is suitable and is widely available in auto parts stores."

This is what's in the RV-3B plans.

Dave

I use Ultra Grey... good stuff!

I'm about to try some Ultra Grey to build up the edge on my front spinner bulkhead to fix the gap between it and the spinner cone. Been using Gorilla Tape strips, but they keep coming loose in the Texas summer heat. A lot of folks use ProSeal for this, but I don't have any on hand at the moment, and I'm betting the Ultra Grey is going to work out well enough. I'll spread a nice even layer around the perimeter with a foam bush, let it cure, and then install the spinner and see how it goes.