Proseal on all skin to rib connections?

[burrm]

So the other day an acquaintance stopped by the hangar. We started talking about proseal as he is in the process of re-sealing some tanks, and he suggested using it basically on almost everything that is riveted, not just the tanks and trailing edges. He's ex-Russian military and said they used it on virtually every skin-to-rib attachment, including on all the rivets. He said something about it adding extra structural integrity on the off chance you experience a flutter event?

Is he pulling my leg? Anybody else ever heard of this or do it themselves? Can't see that it would really hurt anything (other than adding some weight and making a mess), but doesn't seem to me like sealant would add much in terms of actual structural integrity to be worth the hassle?

Personally going to pass on doing it, but just curious and thought I'd throw it out there to see if it's really a thing?

[mfleming]

There are places a little pro seal makes sense, like the trailing edge of the -7 elevators et...

But I couldn't think of a bigger mess and time waster as pro sealing every rivet joint

[sjhurlbut]

Yup I?ve seen this. Not really applicable to RV world but I believe Maule aircraft do this. It?s prob not exact same stuff but it?s done on other metal aircraft.

[rv9builder]

I have no idea if they use ProSeal, but Evektor says they bond all riveted joints on their metal LSAs for extra durability.

[rv8ch]

Lot of work, big mess, extra weight, not needed, but I can see where it would, if done right, increase strength where applied. I'd be worried about unintended consequences.

[plehrke]

Standard practice in military to liquid shim to take up a bit of slop that is designed in to adjust for tolerances or between dis-similar materials. The gap is very tightly controlled and if to big, hard shimming is required. I would not use anything as complicated as proseal. Plenty of other sealants that are out there to do the job that are not two part mixes. I think no need to do this on general aviation sheet metal as they tend to “deform” into taking out the slop, unlike machinings in big jets.

It is false that it adds structural integrity especially if the fill get thick. There is a pretty big structural knock down for liquid shimming. Hard surface to surface is best way to take loads. I had a pile of aluminum shims of everything thickness to take up gaps as I was riveting in odd location where fluted rib did not quit touch the skin. Flutter is exaggerated with sloppy joints not dampened by them. Liquid shimming produces a very flexible joint.

Also if you do all that bonding, you may need to run ground wires or have a bunch of jumpers between structure back to the battery as structure is no longer a reliable electrical return.

[Vlad]

If you are still building and plan to fly some years unpainted, seal the bottom fuselage seams before riveting. Otherwise oil from the breather will find its way inside the fuse.

[chaskuss]

Originally Posted by Vlad

If you are still building and plan to fly some years unpainted, seal the bottom fuselage seams before riveting. Otherwise oil from the breather will find its way inside the fuse.

I hadn't thought of that. Sealing all the faying surfaces and riveted joints is standard practice on the fuselage of pressurized aircraft. I know of several RV Builders down here in southeast Florida who applied proseal along all the lap joint surfaces. I live basically in the corrosion capital of the world, so it makes sense to do anything and everything you can to keep salt ladan moisture out of the structure. Pro sealing the lap joints on your fuselage may, I stress may, help keep the wind noise at a lower level in your cockpit.

Charlie

[jdiehl]

Likewise, I set a small bead of proseal on the fuselage bulkhead/skin interfaces and along the rivet lines underlying the seat pan. No technical/structural reasons other than I presumed it may limit corrosion on these scotchbrited surfaces (yes, they were also primed).

Jim Diehl 7A
Lock Haven, Pa

[mburch]

Excellent idea if you're planning to operate off a carrier.