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To prime or not to prime

J

jet

Member
I am a first time builder and plan to start early March after kit delivery. The RV-12 Maintenance Manual, Chapter 14-2 states all non-alclad aluminum parts must be primed but does not address alclad parts on the interior of the structure. I also note on Sam Buchanan's website that he would probably not prime the interior structure on a next airplane. Any comments on what builders to date have done would be much appreciated.

John
RV-12 kit on order
 
jet said:
I am a first time builder and plan to start early March after kit delivery. The RV-12 Maintenance Manual, Chapter 14-2 states all non-alclad aluminum parts must be primed but does not address alclad parts on the interior of the structure. I also note on Sam Buchanan's website that he would probably not prime the interior structure on a next airplane. Any comments on what builders to date have done would be much appreciated.

John
RV-12 kit on order
Click to expand...

John... As I understand it from talking to the folks at VANS, it is not required that you prime alclad parts on the interior of the structure. Some have primed mating surfaces. So far I have primed the non-alclad parts and alclad exposed sections such as hinges and exposed surfaces that will be difficult to reach after construction.

You could prime the interior of the structure if you wanted to if you live in an area prone to oxidation. Do consider the weight of the primer.

Jeff
 
Non-expert opinion

It's up to you to decide what you want to do - it's your build of your airplane!

I had originally decided not to prime and I think that most RV-12s will be built that way because in most cases, it's not necessary. It certainly will be more difficult and take a lot more time if you decide to prime inside. And there are those who will say that it doesn't work anyway and those who will say that it adds some weight.

I changed my mind when I asked my local flight school mechanics for their opinion. They showed me a wing skin from a Cessna 152 which was badly pitted on the inside surface and had to be removed from that aircraft. They mentioned that they had re-skinned one complete C-172 wing and another C-152 needed to have parts removed due to corrosion. Than having been said, it is important to note that these airplanes were always exposed to the weather and tied down outside. That airport is about 3 miles from the Pacific Ocean. Needless to say, my RV-12 will be treated better but I still plan to use a primer inside of all surfaces. Not worried about the weight factor.

Best of luck to you on the build - love your country.:cool:
 
Hi John

Welcome from another UK RV-12 builder! I'm using a paint called 'Technogrip' to prime all the interior surfaces. This is a single pack etch primer which should keep the mositure and therefore the corrosion at bay.

Where abouts are you based? Shout if I can be of assistance.

Also there's a lot of UK-based RV builders at:

http://groups.yahoo.com/group/rvsqn/
 
I'm priming

Hi John,

I'm also in the UK, and priming everything with two-pack etch primer from Light Aero Spares. To date I have spent 140 hours on priming (and painting the interior) out of 890 hours spent so far, so you can see there's an effort penalty.

Cheers...Keith

www.mykitlog.com/grmps
 
It depends

E. D. Eliot said:
I asked my local flight school mechanics for their opinion. They showed me a wing skin from a Cessna 152 which was badly pitted on the inside surface and had to be removed from that aircraft.
Click to expand...

A friend of mine bought a 152 from Florida and the wings were badly corroded. On the other hand, attached are photos of the inside of my 1980 C-152, now 30 yrs old. It was owned by a local flight school and spent most of its life tied down outside. Based on those photos, I won't be priming when I build my RV-12.

Inside-wing-1.jpg


Inside-wing-2.jpg
 
to prime or not to prime ...

An RV builder friend told me, twenty-five or thirty years from now I would regret my decision not to prime my RV-12 . I answered, I wouldn't be around twenty-five or thirty years from now. He agreed with my assesment ... we both laughed and primer was never mentioned again. ;)

Wow, I never realized it but that's the essence of my signature line.:)
 
John,

If you don't prime the inside you will have to apply Corrosion-X or ACF-50 once its is painted. The English climate will cause even the clad surfaces to start to corrode in a couple of years or so. I suspect the LAA will also insist on some kind of corrosion protection, as might your inspector. Van's will advise that internal priming is not necessary, but they don't live in the UK. My advice would be to prime everything before it is riveted together. It will take longer, but it will be worthwhile in the long run.

Which primer to use is the subject of a never ending debate in which there is no right answer. Ask your inspector, listen to Jerry and select what makes sense to you. In general the preparation is more important than the brand of primer used.

Pete
 
Pete, worry not - John is going to be building and flying his machine in Florida. Given our weather at the moment, I'm not jealous in the slightest. No, really I'm not...! :(

PS We've found at work that Corrosion-X and ACF50 do a really good job of lubricating rivets which is not exactly what you want!
 
Whilst my kit isn't here yet I have just invested in primer and gone for this stuff following a discussion with a friend who's built and RV-7 and used this stuff

Primer - Nexa P565-625
Primer activator - Nexa Standard Activator P275-124

I got it from Brown Brothers who have outlets across the UK so not only am I going to build an aeroplane I'm going to learn how to spray paint!
 
P565 is good paint. We used it on our RV-6. The only reason I used Technogrip was I was told you couldn't get P565 anymore.

It used to be an ICI Autocolour paint. 50/50 mix, no thinners required and you can spray it, brush it and leave it in a sealed jar for a week and it's still good to use. Finish is superb no matter what skill/experience level is attached to the spray gun.
 
I used the same stuff also and have had very good results. I still have some left (unmixed) that is getting on for 20 years old - it works just the same as it did, so no worries about shelf life.

Pete
 
aerofurb said:
P565 is good paint. We used it on our RV-6. The only reason I used Technogrip was I was told you couldn't get P565 anymore.

It used to be an ICI Autocolour paint. 50/50 mix, no thinners required and you can spray it, brush it and leave it in a sealed jar for a week and it's still good to use. Finish is superb no matter what skill/experience level is attached to the spray gun.
Click to expand...

They had to order the paint but it only took 2 days to arrive in a 5L tin which is the smallest size they offer, so hopefully enough for the whole project.

Aerofurb the person who told me about the Nexa stuff was originally told about it by you!! G-OVII

Jason
 
UK vs. Oregon, which is wetter?

penguin said:
John,

Van's will advise that internal priming is not necessary, but they don't live in the UK.

Pete
Click to expand...

Nope, they live in wet, soggy Western Oregon about 50 nautical downwind from the Pacific Ocean. My raingauge 5 miles from them just passed 5" so far this month...
 
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