AntiGravity

AntiGravity

Well Known Member
I've now all but finished riveting the RV-8 fuselage together. Just fitted the seatback support frame. Next step is to flip the fuselage (again), and fit the undercariage. So, in preparation, I went and got my Grove airfoil gear legs down from storage and SHOCK, HORROR. Aaarrrgggghhhh! That looks like corrosion to me, though admittedly I don't know what it should look like (corrosion that is, I know what the gear legs should look like!)

Help! Guys, what's the best way to remove this corrosion; just go at it with 1000grit emery, scotchbrite pad, chemicals, what?

I'm planning on having the legs polished, but the bits that are hidden by the fuselage attachments and fairings will be primered. I want to primer those bits and then drop the legs off at the polishers. When I get them back, what's the best way to treat them to prevent more corrosion in future? Oh, and is there anything I need to discuss with the polishers in the way of special requirements? They made a good job of my motorcycle bits and pieces one time, but these legs are expensive and I'll be relying on them over and over!!

Poor(-ish) photo in my kitlog here...

http://www.mykitlog.com/users/display_log.php?user=jpreou&project=45&category=0&log=45282&row=1

Thanks in advance.
 
Jeff,

As I recall, we acquired our Grove gear at roughly the same time. I have to suspect the long sea journey to New Zealand proved to be a particularily unfriendly environment for its 7075 alloy. At this point, I would think the apparent corrosion visible in your photo is superficial in nature, but its presence....whatever it is....does contain a long term cautionary warning. I'm sure the condition can be neutralized in short order and I encourage you first contact Grove for their input. Asking virtually anonymous open forum members for "shoot from the keyboard advice" on corrosion control measures....especially related to the exotic 7075 alloy is to encourage potential misinformation and conflicting advice. As you know, at $1800 a pair, it is not exactly chump change you are dealing with. Good luck.
 
I agree, call grove. If they don't want to replace it, I?d be glad to help. I've rebuilt several dc-3s at Basler Turbo and bullet holes and corrosion are a given. They have every kind of corrosion possible. What you have should be an easy fix, provided it's not too deep. From the pic it looks like you have filiform corrosion which can lead to pitting and usually comes from improper prep. 7 series is very prone to corrosion. I'm shocked they didn't primer over it right away for more protection. Anyway let me know and I'd be happy to walk you through it.:)
 
Mine have similar but less extensive corrosion on them - mostly in places where I have handled them. I think we got them around the same time (mine came early this year).
I asked Robbie Grove about it at OSH this year. He said just get some fine grit sandpaper and sand it out (even recommended using a little hand orbital sander) - apparently that is how they finish the exterior before shipping. They recommend prime / paint, but he said a good layer of car wax after the sanding should prevent any further corrosion. Don't know about polishing, although I would be interested to hear what you find out, as I would like to do the same.

Thomas
 
TShort said:
......Don't know about polishing, although I would be interested to hear what you find out, as I would like to do the same.
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Just for grins, I started to polish one leg after I received the gear. Without being properly supported, it was a bit cumbersome to do with a 10" buffing motor and Cyclo but the Grove Gear took to readily to polishing. Using the Nuvite system, removing the factory filing marks from the leg was no problem and then it started to take on a mirror-like look fairly quickly. I didn't go much further than a superficial attempt at polishing that one leg because at the time I wasn't sure how much of the leg would be exposed after the fairings were installed and I wanted to epoxy prime all surfaces that were covered up. Since that time, the gear has been installed.....one leg half-polished and the other left alone. But now I do know that when the time comes, the gear will polish up just fine.
 
I asked Robbie Grove about paint vs polish and he recommended paint.

Although I love the look of polished airfoil gear, I've already owned an airplane with a bunch of polished metal and it is a pain in the butt. I'm not talking about alclad, which is no big deal. I'm talking about alloy parts. Even 6061 will develop pits unless you stay on top of things.

I'm looking at some of the new chrome paints, over primer and under clear, but I may just paint with the general airframe color. I'm not gonna polish. I just think 7075 is too iffy.
 
Cheers. I'll drop Grove an email too...

Thanks Guys. Rick, I can't imagine why I didn't think to drop Grove an email :eek: I'll doo that now. I think the corrosion is only superficial. They were absolutely fine when they arrived, but they have of course been unprotected (although inside my attic) for, what, a year or so? I gave one of them a little test rub with a scotchbrite rub and I think it will buff out, but I'll wait for Grove's advice before I go any further. I may also investigate some of that 'chrome' paint as an alternative to polishing. Protection and looks. Thanks.
 
Had a thought.....I'm pretty sure aluminum wheels for cars are polished, then clear-coated. So, two questions. Anybody know what alloy they use to cast those wheels? And with what are they coated?
 
Scott Chastain said:
Dan:

They are anodized a bright silver appearing like aluminum, but the anodization pattern is easy to see. I've never heard of "clear anodized" aluminum. I have the standard Grove gear and installed the stock Van's gear leg fairings. The Grove airfoils are quite a bit heavier and more pricey than mine, and I want to shave off every ounce that I can.

I have seen polished Grove airfoil gear, and although very pretty, you will still need to continue polishing them. I'm not sure about using clear coats over bare aluminum, but my guess is that it will begin peeling off in very short order. :( Here are the options Robbie lists on his website:

Available Options
Polishing?This is an option that we provide or something that you can do yourself. Tip? the entire gear does not have to be polished, only that portion that is visible. The hidden portion should be epoxy primed to prevent corrosion. Polished gear is the least corrosion resistant. Care must be taken to ensure that is always has an adequate coat of wax.

Anodize?Anodizing provides good corrosion protection. Because most anodizing shops have limited-size anodizing tanks, we can offer anodizing only on two piece gear.

Chem Film?Alodine provides some corrosion protection, but not as good as other methods such as epoxy primer. Again tank size is a problem. We are only able to chem film two piece gear.


Scott Chastain
RV-8 N898W
Painting
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Scott,
Do you have any pictures of your silver gear? I was thinking I would be polishing and clear anodizing myself. This local company can do it: http://www.platers.net/services.htm . I'm curious what the silver looks
like.
 
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