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"Wet assembly"

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shmalec

I'm New Here
G'day Folks,
I'm new to RV's but am becoming more and more interested in building one. Many production aircraft are primed and then "wet assembled" for corrosion protection. When I say wet assembled, I mean that all fasteners and mating surfaces are covered in a sealant to prevent moisture from sitting between the two parts. Most corrosion requires some 'electrolyte' to occur and "wet assembly" tries to keep it out of the joints. The moisture could be fuel, rain, condensation etc.
I noticed that the quickbuild kits are not primed and wet assembled. Other than cost, has there been some thought put into this? Is it possible to get QB kits that are primed and wet assembled?
Apologies if this has been covered in another forum. I did a quick search.
Regards
Alec.
 
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I as far as I know I have the only wet assembled RV out there, 1 in 5,000. It does add some weight and you will have a stronger plane.
 
Time, Money and Weight

Alec,

I doubt a quickbuild version will ever be offered as a "wet assemby." I know exactly what you seek. For years I worked new production on the F-18 Hornet and T-45 Goshawk. In addition to each individual part being epoxy primed, salt water aircraft are extensively fay-sealed for added corrosion protection. Working with proseal was a daily fact of life. Even a simple electrical or hydraulic bracket had to be fay-sealed before being riveted into place.

Besides added expense and labor, there would be a weight penalty if you elected to completely fay seal an RV but I have no idea how much. That said, I fay sealed the belly skin prior to riveting for added moisture protection. In addition, I fay sealed the footsteps, rudder cable fairings, data plate...anything that is riveted to the exterior airframe where moisture could gain entry. If I were building a seaplane, I would seriously consider fay sealing the entire structure as part of the routine assembly process but an RV?.....I dunno.
 
TSwezey said:
I as far as I know I have the only wet assembled RV out there, 1 in 5,000. It does add some weight and you will have a stronger plane.
Click to expand...

Nope. I did the same thing on my -6. And I primed everything before assembly with Deft epoxy primer and I bonded all sheet metal joints with 3M 2216 structural adhesive.

Heinrich Gerhardt
RV-6, flying
 
I live in a salt air environment. Everywhere I fly is a salt air environment. You should have seen the rust on the tools and some of the corrosion as we were building the plane. I think it added atleast 50 lbs to my plane.
 
shmalec said:
G'day Folks,
I'm new to RV's but am becoming more and more interested in building one. Many production aircraft are primed and then "wet assembled" for corrosion protection. When I say wet assembled, I mean that all fasteners and mating surfaces are covered in a sealant to prevent moisture from sitting between the two parts. Most corrosion requires some 'electrolyte' to occur and "wet assembly" tries to keep it out of the joints. The moisture could be fuel, rain, condensation etc.
I noticed that the quickbuild kits are not primed and wet assembled. Other than cost, has there been some thought put into this? Is it possible to get QB kits that are primed and wet assembled?
Apologies if this has been covered in another forum. I did a quick search.
Regards
Alec.
Click to expand...
Wet assembly is really a military technique when the customer has loadza money, or the aeroplane will live in a maritime environment. It will add hundreds of hours to the build time, perhaps thousands. QB kits are treated with a wash primer, but it isn't very good at stopping metal worm. I would be amazed if you could even get Van's to consider a request to wet assemble a QB. If you really want wet assembly I suspect the only way is to get a flat pack and assemble it yourself.

Several UK QBs have had corrosion problems in the wings. ACF-50 or Corrosion-X is a reasonable alternative to priming (after final paint). Most UK builder prime the structure before assembly (except QB wings as its difficult to paint where the skins are already riveted on), I don't know how many have gone the whole hog with full wet assembly (btw doesn't have to be a sealant, any chromate loaded paste will do, eg duralac or JC5A). Wet assembly and priming are not issues in many parts of the US due to the dry climate.

Pete
Fully primed 6A in Berkshire
 
I know of at least one builder who ran fillet seals at all the fuselage and wing skin butt joints and lap joints. This, of course, keeps moisture, cleaning products, and other crud from getting under the skins. I was tempted to do it myself but was much too lazy. :eek:
 
Thanks Lads,

There is some info on priming here
http://www.vansaircraft.com/pdf/section 5r9a.pdf
They seem to rely on alclad and wash primer for sheet and the preassembled main spars are gold anodised. They clearly state that rod/angle should be primed or anodised before installation.

Re wet assembly - I've done a little further reseach on common industry practices (I'm sure they vary from company to company). It seems the protection measures are dependant on the joint materials in contact, the fastener material and fit (ie close tolerance or clearance) and the environment. So for example, a clearance fit bolt joining dissimilar materials is more likely to be wet installed than rivetted ali sheet of the same material. Anything in a maritime environment is likely to get full wet assembly everywhere. Measures are generally some combination of faying surface seal, edge fillet, shank and/or head and tail wet install. The large areas of ali riveted 2024-T3 sheet (all same material) on the RVs may not warrant any special treatment if you keep it out of the weather and don't live by the coast.

All complete speculation and opinion of course. :) Alec.
 
Wet built Rocket

I recall reading an article in Sport Aviation about four years ago about a guy in California who built a (Harmon?) Rocket. His built time was crazy high, like 4-6k hours. In fairness, it was a beautiful plane but I don't think I could justify the extra time and effort.
 
JC5A

I'm wet assembling an RV8 with JC5A. Normal priming then putting JC5A on the joints. JC5A is a chromate paste. To put it on is minimal time, i.e for all the joints on the big wing skins it takes about 2 to 3 minutes at most. A small tin of JC5A weighs about a 1lb and there is enough in there to do a couple of RV's. You only need a very thin wiping on the joints. I did quite a bit of research into this before I started building and have followed normal local aircraft maintenance proceedures. JC5A does not harden and as the airframe flexes, it flexes with it there by keeping a nice chromate joint. Two problems with JC5A. 1. Cost. I paid aprrox $120 for a small tin. 2. Can make riviting a bit slippery which is a non problem if you keep the snaps and bucking bars wiped. So for me it was a no brainer due to the fact I live in a high corrosion area. The RV's that have been built locally in our small group have used the same method.
 
I know this is an old thread but it seemed appropriate to post it here...

Does wet assembling interfere with conductivity between the parts?
 
rv8or said:
I'm wet assembling an RV8 with JC5A. Normal priming then putting JC5A on the joints. JC5A is a chromate paste. To put it on is minimal time, i.e for all the joints on the big wing skins it takes about 2 to 3 minutes at most. A small tin of JC5A weighs about a 1lb and there is enough in there to do a couple of RV's. You only need a very thin wiping on the joints. I did quite a bit of research into this before I started building and have followed normal local aircraft maintenance proceedures. JC5A does not harden and as the airframe flexes, it flexes with it there by keeping a nice chromate joint. Two problems with JC5A. 1. Cost. I paid aprrox $120 for a small tin. 2. Can make riviting a bit slippery which is a non problem if you keep the snaps and bucking bars wiped. So for me it was a no brainer due to the fact I live in a high corrosion area. The RV's that have been built locally in our small group have used the same method.
Click to expand...

Unfortunately JC5 is also known to cause cancer.
 
JetMech72 said:
I know this is an old thread but it seemed appropriate to post it here...

Does wet assembling interfere with conductivity between the parts?
Click to expand...

Not really because the rivets are still metal to metal.
We have had no problems running current through the fuselage.
 
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TSwezey said:
I live in a salt air environment. Everywhere I fly is a salt air environment. You should have seen the rust on the tools and some of the corrosion as we were building the plane. I think it added atleast 50 lbs to my plane.
Click to expand...

Considering that tank sealant weighs about 2 lbs per quart (actually a little less) I think you will have to find another source of excess weight (making the asumption you did not use 25 quarts of sealant).
 
RV72004

Quote "Unfortunately JC5 is also known to cause cancer."

Can you back this statement up with scientific papers and confirmed data.

Interrested so that I can take appropriate precautions.

Thanks
rv8or
 
rv8or said:
RV72004

Quote "Unfortunately JC5 is also known to cause cancer."

Can you back this statement up with scientific papers and confirmed data.

Interrested so that I can take appropriate precautions.

Thanks
rv8or
Click to expand...

Seems like Ted found all the correct info. My info was word of mouth from Airforce technicians who told me not to touch the stuff without gloves. I suppose the odd time wont cause too many issues, but building a whole plane should be treated with care.
 
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