anti-shimmy leg stiffeners

[fixnflyguy]

Bret,
The term RTV (Room Temperature Vulcanizing) hosts a variety of manufacturers and compounds. There are some that contain Acetic Acid which releases during the cure (smells like strong vinegar) that are harmfull to most metals and electronics. I work in Aviation Maintenance at my day job, and there are many RTVs that are formulated without the Acids..but if you dont know the type to get at the Big Box store aviation department, you may induce the acid corrosion problem. I am just a fan of the Proseal type products which bond well and seldom lead to any moisture incursion. Proseal is also paintable, RTV is not. Im not trying to say that everyone using RTV should worry, Im just saying there are better options if you are at square one.

[rv7charlie]

Much bigger deal with electronics than with metals. A friend who raced rotary powered cars for decades used GE silicone bath caulk (acetic cure) in place of the block-to-exhaust manifold gasket. It's in contact with cast iron, aluminum, & probably some stainless or more exotic metal in the exhaust port. Rotary exhaust temps are legendary (of course, the actual metal is never that hot).

If you need something quick & want to avoid the acetic acid cure, just look for 'sensor safe' on the RTV packaging at the auto parts store.

Charlie

[Jpm757]

On my Six, after epoxy priming gear legs, I got 2 big pieces of electrical heat shrink tubing and shrunk it to each gear leg (before installing brake flanges). That stuff is pretty darn tough! I wound up not having a shimmey problem. I wonder if the heat shrink, or maybe multiple layers had any effect?
Jake

[CAVU Mark]

I like this idea so am curious as to what diameter heat shrink you used? Thanks.

[Doug Eves]

My RV6 gear leg fairings are the sealed variety that have been filled with foam along with the wood stiffeners. My close friend who is a master craftsman and built many aircraft (including Rv's) has been after me for year to remove it all to inspect the condition of the legs for corrosion. Also he says that the stiffeners concentrates the bending moment of the leg's entire length down to a short area. This can/will eventually weaken the steel in that area. He says this is contrary to the original design of the gear. He has removed this same set up from another 6 recently and found alot of corrosion. I haven't decided yet weather to remove mine as they are beautiful (to look at at least) and haven't caused me any heat ache yet. Has any heard of gear failure?

[rv7charlie]

No argument on the corrosion issue; with steel it can never be ignored completely. But on the effect of the stiffeners: The Van's-recommended technique (and all the ones I've seen) show adding fore-aft dimension, with minimal change in up-down dimension. My impression, FWIW, is that the stiffeners effectively convert the round rod to a 'slab', similar to the RV-8's leg. The primary flex is up-down, and the fore-aft flex is just an unwelcome byproduct of the round leg. So the stiffeners shouldn't have the effect your friend is concerned about. Again, just my opinion...

[Doug Eves]

So I have revisited this topic again with my nameless friend.. (Most of)His comments are as follows. The gear is tapered spring steel designed to distribute the load induced deflection evenly over the entire length of the leg. Hollowed wooden stiffeners placed securely on the legs prevent this (in all directions) and concentrate the bending moment to a small area of the leg. Contrary to original design. (not Vans). The "unwelcomed" fore and aft movement that you speak of is indeed a beneficial, designed improvement over cessna type gear (RV8). In that type of gear,those loads are transmitted directly to the airframe as the gear has no give in that direction. If one has the gear properly aligned while using good, balanced tires there is no need for strapping wood on the gear legs and filling the fairings with foam. There should be no shimmy.

[Doug Eves]

By the way. Mine have the wood and foam. I have decided to remove the fairings which will get destroyed when I do remove them but I really want to know about the corrosion.(or not) When I replace them there will be no wood or foam so I will let you know what happens and whether this theory holds water! LOL