corrision issues

[Sky_Dog]

Hello,
I'm not a kitfox onwner yet, but I have been looking at lots of pictures. I have been really interested in the folding wings becasue I would like to store my plane in my garage. One question I have is, looking at some pictures online, it seems like there is could be a problem with corrision where the aluminum spar contacts the steel fusalage forward pin. Has anybody seen any issues there? Also has there been any corrosion issues where the jurry strut mounts to the spar? Thanks!

[Geowitz]

In a nutshell, no, you won't have any problems with corrosion in those areas as long as you follow best practices in your construction. There are steel tabs that rivet to the aluminum spar where the pins go through to reinforce the pin connection and the jury struts use the same type hardware. The use of stainless steel rivets, corrsion inhibiting paint, and epoxy keeps the dissimilar metals apart. Lubricating the clevis pin and holes helps with corrosion as well. The clevis pin is AN and is cadmium plated??... I believe which helps with corrosion issues too.

[Dave S]

Travis,

First off - the aluminum alloy used in the spars is less succeptible to corrosion than other aluminum alloys.

Where steel parts are connected to the spars, such as the lift strut attach points, the fuselage pin tabs, lift strut attach brackets and the drag tube attach points, a specific product and technique is provided with the kit to avoid steel to aluminum contact and seal the contact area with a bonding agent where steel parts are attached directly to the aluminum.

For maintenance purposes - I use a thin coat of grease on the pins - virtually all of the pin contact is with the steel.

I have never heard of any issues with corrosion at these points. If a person sticks to procedures and materials used with the kit and good practices in construction - should never be an issue.



A couple additional thoughts - Consider how certified aircraft are built:

1) The piper tripacer and similar have a steel tube fuselage, aluminum I beam spars bolted to steel lift strut brackets and the steel fuselage with steel bolts.

2) Cessna aircraft, piper 28 series, beech & dare I say airliners - all have steel bolts/pins/brackets or whatever associated with the aluminum spars - also dis-similar metals.

3) Keeping corrosion at bay is really a matter of proper construction, corrosion protection, inspection and maintenance. Part of maintenance is proper storage - hangar it - rather than tie it down out in the rain and other grunt.


For what it is worth - one of the things that drove me to a new homebuilt kitfox as opposed to an old beat to crap rental aluminum aircraft was consideration of of the corrosion factor.

Cases in point - 1) seeing those little donut shaped swelling areas around rivets on wings of a weathered aluminum skin airplane. 2) Seeing a beech musketeer with a spar patch because of a "flower shaped" corrosion blossom at mid wing.

In my opinion - a new Kitfox Home built is far superior on corrosion issues for a number of reasons:

a) If you build a new one - it's new - meaning no corrosion to start

b) The kit instructions include corrosion prevention steps and the builder can take corrosion prevention steps during the build that offers far more corrosion protection than what most of those 30 - 40 year old certified aircraft that are still flying ever had.

c) The builder/repairman/owner of a homebuilt aircraft is entirely free to inspect to the hignest standard they want to - not limited to time/$/hr

d) A tube and fabric aircraft like the kitfox is far superior, in my opinion, with regard to the ability to easily inspect, maintain and repair the structure. You can pretty much see everything you need to in order to insure a complete inspection. When the fabric is replaced after 20 years - you have a fresh start at full inspection and repairing any corrosion that may have developed under the fabric. It is a bit more work, in my opinion, to de-skin and re-skin an entire aluminum airplane if you are really going to inspect all of the numerous lap seams which cannot be inspected any other way.

The Kitfox is a great design - like any other aircraft - continued airworthiness is in the hands of proper construction, inspection and maintenance - no different than a properly maintained certified aircraft.

I don't think you have much to worry about if you do your part correctly.



Dave S
KF7 Trigear
912ULS Warp Drive