Re: Varieze wing fittings


jack hohner
 




---In canard-aviators@..., <marc_zeitlin@...> wrote :

I will be very surprised if any weld inspection service would tell you that they could give you any useful information about the corrosion state of AL plates buried in fiberglass assemblies without any known reference samples.

Marc, I think you should educate yourself on the process and surprise yourself.  An x-ray of the wing fittings would reveal corrosion as clearly as if you stripped the fiberglass off.  Perhaps better, the pitting from corrosion will show up as dark spots on the film.  Whereas aluminum to the naked eye sometimes does not show much contrast between the corroded and non-corroded areas.

As far as a data base, there have been zillions of structural connections that have had x-ray testing.  We are not inventing the wheel here.  One thing that someone active in the experimental market knows well is that you do not go into a non-aircraft vendor or service, say a machine shop...and tell them you need a part for an airplane.  If the shop doesn't know you they will just tell you they won't do it.  If its someone you know then they will give you some sort of excuse.  Such is what I suspect from your friend that wants a ten sample data base, etc.  If your market sampling is only one vendor for NDT, then I suggest you expand that.  And maybe not mention its for an airplane.

Another suggestion I made when this thread was going around before is an easy static load test.  Although your dynamic load testing with a parachute is doable, I am not sure it is the best solution.  A simple steel jig could be fabricated that would allow the Varieze owner to test his fittings.  You would not need to invert the plane or get a lot of shot bags.  When I suggested it before  someone
(possibly you) dissed it on the argument that the lapped tapered pins would not match the jig.  Recognizing that my volunteer help was not welcome...I dropped the effort.  However, my heart goes out to the Vari owners who are grounded by the propagated fear from misleading information.  A misrepresented static test to failure of a donated Vari comes to mind.  And now telling them they can't do an X-ray test or easy load test.  One wonders if you have something against Varieze's.  The problem is simple... Varieze's require a positive test of their wing fittings.  The solution is simple for Vari owners.  Either a non destructive test that clearly reveals any presence of corrosion.  Or a simple non-destructive static test to 5 g's or more.  I suggest we don't make it more complicated than it is.
Back to the test jig.  A pin with some play in the test jig does not have to have the tight tolerance of the lapped pin.  We do not have to worry about any wiggle in the wing.  Loaded positively, the test pin and fitting, in either a positive G load or negative load, would remove any slop.  We are not flying here so it does not matter if the wing can be wiggled.  
Anyways, your mission to see that all Vari's are either grounded, or fly below 2 G's and their owners flying in perpetual fear I think is misplaced.  I have always admired the "can do" attitude that exists in the experimental arena of flying.  Verifying Varieze wing fittings to a high level of safety is easily doable...lets help make it happen.
Jack Hohner

 

Join canard-aviators@canardzone.groups.io to automatically receive all group messages.