What is this funk and how do I remove it safely?

[fotoman1527]

I have this type of funk buildup around all four side lights on my 2012 FC27 FB.

I wonder if anyone knows what it is and how to remove it safely. Goo off didn't work, and I want to stop whatever it is from spreading and damaging clear coat or aluminum. Thank you!

[fotoman1527]

I should add that all four lights work perfectly.

[SteveSueMac]

I'm tempted to suggest it's filiform corrosion (lots of threads on that topic in the forums - just google "Airforums filiform corrosion" and you'll get a bunch of threads to read, like these:

https://www.google.com/search?q=airf...iw=375&bih=628

However - that usually looks more like veins - yours looks like blotches and on the pic, like a couple drips at the bottom. Are you the first owner? If so - can you recall applying anything for cleaning there? If not - could you contact the prior owner?

[cliffcharb]

I would try some swirl remover or polish to see if it comes off. Neither of those would hurt the finish. At first it looks like corrosion but it also looks like it might be on top as I see scratch marks in it, possibly where you were trying to scrape it off? I'd also be inclined to take the marker light off to see underneath it and see if its not related to the light housing and or gasket

[VaTravelers]

It looks like dissimilar metal corrosion. It reminds me of the corrosion we saw on our Navy airplanes. You can treat it but it requires removing the corrosion completely and repairing the damage.

[Boxite]

It looks like you have two things going on there.
There appears to be a light case of filiform corrosion, which is causing the clearcoating to delaminate, and it appears that water has slipped beneath the clearcoating from the light-fixture, which is likely the causation of the matter.
I suggest you remove the light fixture and mask/tape off the area. Remove the clearcoat, then use a scotch-brite pad to remove the corrosion. Next polish the area to match the surrounding, undamaged skin. Then apply automotive clearcoating (available from auto paint suppliers in nail-polish-bottle sizes as well as aerosol cans) and let dry.
Clean up the light fixture, REseal the gasket at the base of the light fixture, and reinstall it.
It should only take a couple hours after you get all your materials in-hand.
Airstream dealers or the factory should be able to provide the materials for stripping and polishing.

[A W Warn]

I think somebody sprayed something onto the preexisting filiform corrosion. Whatever it was dried and left a film (that white funk). It looks like (I'm guessing) that it is an interior finish coat for wood, not intended for exterior or automotive use (maybe a rattle can urethane). Will it scrape off with your fingernail?

[Wingeezer]

My feeling is just like Alan's - looks as though someone has sprayed something (?) to try to deal with a filiform corrosion issue. No idea what it was, but itit did make a mess!

Hopefully you can get it off, then do what you can to carefully scrape away traces of corrosion and loose clear coat to arrest filiform and coat with a clear coat pen or similar to provide protection.

In the past, I have tried to scrape off filiform then touch up with a variety of silver / alum. paints but never had much success in being close to matching the orignal finish of the aluminium, so more recently I just scrape to clean aluminum and then clearcoat.

If anyone has ever found some brand of alum. paint that does a better job, I'd certainly appreciate specific info!

Brian.

[aircraft1]

You may be missing a gasket on the base of the parking lights and you have dissimilar metals coming together causing expholiation Corrosion common on aluminum exposed to salt air.

[franklyfrank]

Originally Posted by fotoman1527

Attachment 272462Attachment 272463

I have this type of funk buildup around all four side lights on my 2012 FC27 FB.

I wonder if anyone knows what it is and how to remove it safely. Goo off didn't work, and I want to stop whatever it is from spreading and damaging clear coat or aluminum. Thank you!

Your lights look like they are missing the rubber gaskets. They isolate the cast metal and the aluminum and keep it from corroding. I had one light with the same problem on our 2013 trailer. Of course you also have some gook on the corroded areas. You will have to remove the lights clean up everything, apply corrosion treatment and reinstall all with rubber gaskets.
Mine was taken care of at JC even though I was out of warranty.

[tjdonahoe]

Interesting, not much of the corrosion here in Montana,must be the salt in the air near the coast...

[fotoman1527]

A hearty and belated thanks to all who replied! I was waiting to reply to your ideas until an AS dealer saw the damage. That has now occurred, but unfortunately their insight was limited to saying they thought something was wrong with the skin and they couldn't address it! To disabuse you of a few red herrings, there are gaskets; the discoloration from a suspected spray was from me, and I WAS able to remove it. I plan to follow Boxite's plan, but am not sure how to remove the marker lights. Thanks to all!

[Boxite]

Originally Posted by fotoman1527

A hearty and belated thanks to all who replied! I was waiting to reply to your ideas until an AS dealer saw the damage. That has now occurred, but unfortunately their insight was limited to saying they thought something was wrong with the skin and they couldn't address it! To disabuse you of a few red herrings, there are gaskets; the discoloration from a suspected spray was from me, and I WAS able to remove it. I plan to follow Boxite's plan, but am not sure how to remove the marker lights. Thanks to all!

Let me add that as you remove the corrosion with the scotchbrite pad to first observe the "grain" of the surrounding aluminum and make the passes with the pad in the same direction. I.E., not a circular motion, etc.
The same goes for the final polish..... use motions aligned with existing "grain" or the repair will be obvous....Good repair... but an obvious one, (if the intent is to return the area to original look.)

Hope this helps.
George (experienced aluminum polisher)