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ao.frog

Well Known Member
Hi.

I've just handed in the wings to the paintshop and the painter said that I schould consider applying Sicaflex to the outside of the wings where the wingskins meet up.

He said that water could enter the inside of the wings through those small "cracks" and cause corrosion over time.

He said to apply a very small amount (1 mm wide) along the wingskin joints would be easy and almost invisible and make the wings "waterproof".

He also said he preferred Sicaflex over RTV since Sicaflex can be painted, allthough he recommended the Sicaflex application to be made AFTER the wings had been painted, I.e on top of the paint. (the Sicaflex comes in a "clear" version)

He also said that he recommended the same thing to be done along the sides of the canopy and the aft window. (I've a tip-up canopy)

So what do you guys with flying RV's say: can small amount of water enter the inside of the wings and/or canopy when flying through rain or is the RV "waterproof" as it is?
 
Alf, (from the wet UK to even wetter Norway) that is not the way it is usually done, and certainly not the way I would do it.

Just before it flies I will spray ACF-50 everywhere. There are other similar products. It creeps deep into the joints and displaces water and stops/halts corrosion. It and similar products are designed for the job. (I did my -9a this way and it was very interestng to see how it found its way into every nook and cranny. After the first few flights there were traces of it everywhere at joints on the outside of the aircraft in low pressure areas. It easily wiped off.)

My concern re your painter's idea would be that water gets trapped behind the sikaflex and promotes corrosion. Sikaflex is also heavy.

I did in fact bond my canopy on with Sikaflex http://gikonfinsh.blogspot.com/2007/06/what-i-wish-i-had-understood-about.html#linksso that will be waterproof, but since the joint is made with Sikaflex there should be no small gap to trap water.

Just my thoughts, but hopefully based on logic.

Best wishes, Steve.
 
Alf,
In the world of large pressurized aircraft such as Boeing,Airbus,ect., the entire airframe is put together "wet" with the same type pro-seal product as used to seal your tanks. Virtually all seams,joints,and most fairing panels ar also seam sealed after assembly. it is a two fold need for sealing the pressurization in the fuselage, and sealing the fuel into the wings as well as keeping moisture out at 500 mph. I have sealed some joints on my RV-4 with it just to keep it slightly more water tight, but in reallity ,it is not going to help much in corrosion prevention...in fact, unless you had applied it to all the over-lapping skins during assembly, it may even retain moisture and inhibit drying out of the seams. Proseal is paintable, and will last forever if you are still looking for a seam filler..I also installed my fiberglass empenage tips with it to fill the voids and just wipe it smooth with a cloth moistened with MEK or Acetone. Good luck and dont wory so much about corrosion..just keep it hangared and it will last longer than you need to worry!

Bill E.
RV-4 painting/final assembly
 
Corrosion X

....is a really good way to go as Steve points out. In our ag aviation environment, even he ribs and skins are painted on the inside as well as the outside.

Nevertheless, we still fog Corrosion X in the wings, tail and fuse every three years or so..very good protection,

Regards,
 
ACF-50 then...

Hi.

Thanks for the input guys. It's soooo nice to have this forum!

We'll skip the Sicaflex and use the ACF then.
That sure seems alot easier and makes more sense too.

I like the idea that it also lubricates joints etc.

Using Sica could've been a costly mistake....
 
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Beware of proseal weight!
Had a buddy build his super 7 with every joint having proseal used a structural adhesive (He was a mechanic for a commercial heavy)

He came out very fat on the weight.
He was not happy.

As with anything added, be sure it serves an actual purpose that can be articulated, weighted against its disadvantages. Here its time, money, weight, and hassle factor to name a few of the dis's

Best,
 
I think that you will need to be careful if you spray some anti-corrosion products in the interior of the wings and fuselage before you paint. Some will prevent the paint from sticking, I have read. After painting, you can just wipe or wash these products off so there is no problem.
 
ao.frog said:
Hi.
So what do you guys with flying RV's say: can small amount of water enter the inside of the wings and/or canopy when flying through rain or is the RV "waterproof" as it is?
Click to expand...

I saw the answer to that one late last year. A Beech Debonair based at our field lost his vacuum system in rain. Water had found its way into the vacuum inlet tube and ruined the DG and AI. Quite a few bucks damage. THEN the A&P checked the right side of the airframe. All the horizontal bracing forward of the door was rotten! Some would pull loose by hand. Very expensive repair, all because of a small windshield leak. RV's aren't immune from water-caused corrosion. I do think it is also a reason to pull any insulation every year.

Bob Kelly
 
Navy and Marine Corps aircraft live and work in a very corrosive and hostile environment. Pro sealed lap joints are specified to keep salt water and vapor from entering the joints. Aluminum skin joints are sealed with pro seal after allodine, before priming and paint. Tape off both sides of the joint line and apply with a narrow spatula. Remove the tape after it sets up a bit. You are just making a small fillet over the end of the lap joint so a little pro seal will go a LONG WAY. Your skin is only .020 thick so the fillet won't be very deep. Most of the pro seal will be sacrificed when the tape is removed.

Not a fun job but, your skin joints will be water proof.

Jekyll
 
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