Panther Sport Aircraft Forums

We used a product called "Never-Dull" on our show tractors and trailers. It looks like cotton- pull a piece out of the can and rub till it shines the way you want it to. the last time I bought it it was about $10 a can. Two cans would come close to doing a Panther. Most Truckstops have it in their store.

Paul,

Which route did you go with the priming? Acid Etch from NAPA, Epoxy Primer, Zinc Chromate, Alodine? And, what were the process steps?

Also, Dan mentioned an aluminum cleaner used to clean the aluminum on tractor-trailer trucks that was inexpensive and worked well. I can't remember the name, but am looking for any hints on how I might add some corrosion protection - especially in the tight seams.

Related, what type of primer will you put underneath the paint on the outside?

Lastly, none if this is intended to take away from the key message, that "6061 is very corrosion resistant".

Let us know.

Thanks,

Bob Jacoby
Panther SN018

Mike,

Track down some Alabama Sonex folks and pick their brains. Same construction materials as the Panther.

Plug Alabama in here: http://builder.sonexaircraft.com/cgi-bin/search.pl

Tony

Paul,

Thanks for spending the time to post your thoughts and knowledge on this topic. My Panther will be hangared in several locations but two in particular do not provide much protection from the extreme humidity that we get here on occasion. I also plan to attend plenty of fly-in’s and there is always the chance of dealing with rain. Guess I’ll have to beat the dead horse a little longer ….

Mike

If you would like an engineers perspective on corrosion control, I will off this.

I am an structural engineer with the US Navy, and work with corrosion repair and protection all of the time.

Most of your commerical and Military aircraft use 7000 series aluminum as the primary structure, and must be protected against corrosion. The only 7075 on the Panther is the landing gear legs, that should be primed and painted.

2000 series aluminum is much better against corrosion that 7000 series aluminum, and the Navy alodines and primes all of their 2024 parts also.

6000 series aluminum is the best against corrosion and is not really necessary to prime. The Panther uses this for all aluminum structure with the exception of the landing gear legs.

Having said all of that, all corrosion requires an electrolyte and a tight space. Water typically serves as that electrolyte. If you plan on keeping your aircraft in the hangar and mainly flying in sunny weather (typical Panther flying) then priming and painting 6061 is not as necessary.

When it comes to what to use as the protection, Alodine and Zinc Chromate is still the best, and everything is compared to that about protection. Adam is correct that Military and Commericial aircraft uses epoxy primer, but that is mainly because of Hazmat concerns of Chromates, not because epoxy is better. The Navy uses alodine then 2 thin coats of epoxy primer for all of their parts.

All aluminum requires some type of etching for the primer to adhere, if you use alodine, part of it's process is to etch, and while the part is still wet, alodine it. Then dry and prime it. Some primers are self-etching, and if you use that, I would probably not alodine the part, as the etching would probably damage the thin alodine coating. I believe AKZO from Aircraft Spruce is self-etching, and in at least one letter, they recommended not to use alodine. There are many versions of AKZO primers listed on their website, and I had problems figuring out what ACS sells compared to the AKZO website. AKZO is a large supplier of paints and primers to Commercial Airliners and Military aircraft.

Etchants and Alodines contain acids, and they have to be rinsed off well. If you use them, it is recommended to do it before assembly where they can be rinsed well. If done, after assembly use a lot of water to get the acid out of all of joints, or you might be worse off than not doing anything on 6061 aluminum.

Water can destroy everything including rocks, so keeping aluminum dry is the best corrosion protection. Even with all we do on Navy aircraft, we have signifcant corrosion problems with the 7075. But that is in the worst possible environment, constant salt water baths, and very little fresh water to clean the planes with. You can never eliminate corrosion, just slow it down.

As you will probably see in some pictures for the builders manual and on the website later, I am priming the interior components. But mainly that is because I expect my plane to be sitting on wet flight lines at a lot at airshows and other airports. And I will certainly admit to a bias towards protection because of the damage I see at work on Navy aircraft, which is certainly worse than most homebuilts will ever see.

Most important thing, get the airplane finished. As Dan said once, all the corrosion protection in the world doesn't help, if you never get it flying. Don't let alodines, primers and paint be the reason to not finish a Panther.