Rust on Gear Leg

Hi All,
Hoping to get some good advice for solving my latest issue. My installed main gear legs have developed "rust freckles". Both have been installed for about 4 years (really slow build) and both have the original powder coating as received from Vans. I suspect with some of the wild temp and humidity swings has caused condensation to settle on the gear thereby making the rust freckles. So, given they are installed, can I sand down the powder coating, clean, prime and paint. Or should I consider removing them and having them stripped and re-powder coated?

A little oil and steel wool should take care of it. Then degrease it and prime/paint it.

Let the paint dry, then coat it with ACF 50.

I'm not a mechanic but that's what I would do.

A quick sand (no need to go to bare metal) followed by an ospho soaking (phosphoric acid - converts the the rust to an inert iron compound) then paint

Where the gear fairings installed?
Powder coating is usually pretty tough and it surprises me to see this.
Must be a bad environment or something not right with the powder coating.

JonJay said:

Where the gear fairings installed?
Powder coating is usually pretty tough and it surprises me to see this.
Must be a bad environment or something not right with the powder coating.

Click to expand...

The powder coat on my main gear legs was pretty much junk. I was able to wipe it right off with some acetone on a rag. The nose gear leg did not have the same issue, acetone won't hurt it at all. Maybe a bad batch, or the supplier switched to something else.

I decided to repaint the gear legs. I stripped the factory power coat (using just a rag and acetone), epoxy primed and top coated with the same urethane I used on the exterior.

I would consider the existing coating to be suspect, so I'd pull 'em, strip 'em, work the surface, and repaint.

They are highly stressed springs, and as such, should not be allowed to develop rust pitting. Given they get buried inside fairings and not inspected very much, they need to be sealed.

One of my legs had this

Dry storage. Not yet installed. I sanded it down to metal with 400 grit and hit it with rattle can primer and epoxy appliance enamel. Note the "rash" on the upper outer portion of the leg, through the powder coat. I have a better pic I'm hunting for...

Same thing was noted on my flying 6A after a few years when the glass-wrapped wooden stiffeners were removed. Same treatment - sanded out, repainted, stiffeners NOT reinstalled...

Dan - I would consider calling Vans with your serial number and date you received the gear. They should be able to track the batch, assuming their vendor produces them as such.
There may be more gear legs out there with compromised powder coating, flying and yet to be discovered, or still sitting in kits.

As mentioned, these get buried under fairings with minimal inspection. Removal of the gear leg fairings and inspection of the part of the leg hidden is on my 500 hour inspection interval. If folks wait that long, they could be corroded beyond repair. Mine passed inspection and remain as a 500 hour item. I am hangared. If I wasn?t, that interval would be shortened.

Since I operate 99% from turf, no. Don't notice their absence.

Better closeup photo found

It was only present on one of the two legs

As widespread as this is, and appearing on never-flown gear, I wonder if there is a process problem becoming apparent.

It certainly isn't reassuring.

Bill Boyd said:

It was only present on one of the two legs

Click to expand...

Actually, this doesn't look like corrosion. I have seen this before whereby the powder coating had adhesion issues due to contamination during the prep. I had a few spots on my motor mount similar to this. There was no rust just poor adhesion. Of course, left untreated it certainly will start to oxidize and corrode.

my family owns a powder coating operation, that looks like typical case of letting the parts set to long between prep to powder. it is very important to get the parts straight from abrasive blast, or chem prep straight to the powder booth. here in florida, if we blast parts on second shift and wait for first shift to shoot them that happens because of the high humidity and salt content of the air here. it sometimes takes a while, but he oxidation process starts as soon as its prepped, and if moisture and oxidation is present when the powder goes on that WILL happen.

bob burns
RV-4 N82RB

Then it was certainly "left untreated." (I had the kit for 3 years before getting to this stage, and it had been in the possession of others for maybe 5 more). When I sanded it down, there was certainly Fe2O3 in evidence. Not much, but the sandpaper was definitely brown.

Whatever the final result, it would be interesting to see if the root cause is the same and can be identified/remedied. Meanwhile, inspections are a good idea as part of the annual. Fairings are not hard to pull.

Strip

Strip that bad powder coat job off and use rattle can Porsche-15. Did that with my Mooney nose gear.

I spent 34 years in the metal coatings removal business. Most likely cause is improper application of the powder coating. Incomplete precleaning/prep,insufficient thickness applied or underbake.

In the area where the coating is bubbled you must remove down to the bare steel or you will geet filiform corrosion under the new coating.

Fleet issue?

Now I guess we wait for the factory to weigh in on this.

It's like waiting for the replacement part to do the -10 engine mount SB. Apparently there's a shortage of those steel plates. Maybe they're checking the powder coat twice before they let them out the door

Mothership says....

take to a convenient place to have them re-powder coated as the preferred option as it would hold up better to abrasion caused by the gear fairings. Second option is to strip and repaint with a quality primer and paint. No mention of being concerned about my particular lot being powder coating defective. So, basically, I am on my own.

Quick response to my email last night. The answer is not unexpected and kinda what I expected and aligns with then responses to my post here (Thank ya'll for taking the time to respond).

So, assuming I go the re-powder coating route, I get to figure out how to go about lifting the airplane with wings and engine, etc installed where it is supported enough to not cause any damage to the plane or me. I have seen/heard/read there are jacks that can be used at the tie down points. Is this the best solution for lifting the whole plane high enough to get the gear out of the main gear weldments?

By the way, I found the same "Rust Freckling" on my elevator horns. I guess my best option there is to strip/treat/prime and paint as disassembling the elevator horns from the elevators would do more harm than good.

Man, if I knew what I know now back in 2010, I would have had all of the powder coated parts redone.

Gear coatings food for thought.

I have 1999 RV4 kit with good powder coated parts. BUT, Acetone will take it off.
Epoxy and 2K urethane are not affected as we all know.
For the experts:
1- Should good powdercoat be immune to Acetone ?
2- I wrapped my -3 gear with glass and West 105, to isolate it for Carbon Fiber stiffeners and fairings. Any concerns about West 105 endurance on clean (chemically) gear leggs ?

There are lots of different type of powder coatings. Polyester, polyester TGIC and epoxy are the main three groups. Polyester is the most likely to be removed with acetone or MEK. The ability to use solvent to remove varies with the amount of bake time and sometimes varies with changing colors. Generally TGIC is more solvent resistant and best in sunshine tolerance and epoxy has the best solvency resistance but mediocre sunshine resistance.