Should I seal the flanges when Reinstalling the wing tanks on my Piper after inspection

[Morgan3820]

my AI did the SB 1006 spar inspection. Happily everything looked as new. Should I put a small bead of RTV or other sealant on the flanges when reinstalling? While it could make the next inspection more difficult, I would think that keeping water out would be a good idea.

 

[Kenny Phillips]

Does the manual say to? If not, then not. Also, RTV releases acetic acid whilst curing, which can instigate corrosion.

 

[Mooneys R Quicker]

I have heard the same thing about RTV and aluminum, Supposedly When RTV starts curing it also starts a corrosion process.

 

[Capt. Geoffrey Thorpe]

There is RTV and there is RTV.
Some is very corrosive (typically the stuff from Lowe's Depot. (Smells like vinegar when you use it from the acetic acid as noted above) and there is electronic grade RTV that is non-corrosive. RTV is also not that good as an adhesive - think of it more as a gasket than a sealant.
Polysulfides stick better, but don't use if there is plastic involved.
Don't know if a sealant is a good idea in general, but if you do use it, at least get the right kind. You might ask your A&P.

 

[kgruber]

Use JB Weld.

 

[alfadog]

Don't know how much use it would be on the outside of the seam but I would use 2-part polysulfide B2 sealant.

https://www.aircraftspruce.com/catalog/appages/prosealant.php

You can buy an applicator for the Semkit or just cut it open after mixing by hand.

edit: I thought you were referring to the tank seams, not the seam between wing and tank. If the airplane did fine all these years without...

 

[Dan Thomas]

Putting sealant on the skins of an aircraft wing can cause structural problems. That tank cover is part of the wing's structure, forming part of the box that keeps it rigid against twisting. Sealant can act as a lubricant, letting the wing twist a little and leading to more trouble than you want to know about. I could see cracking from the rivets of the other skins, for instance, as they try to take the torsion loads that the tank cover should be taking. I wouldn't use anything unless the OEM specified it in their service manual.