Have any builders as yet attempted this mod and if so with what level of
success ?
Since recieving Ivans letter regarding the mod I had been hoping that someone
would come up with a more practical method of resolving the problem. Since I
am nowhere near completing my aircraft this particular obstacle is not a
pressing matter however having thought through what is involved (or what
appears to be involved), the idea of attempting to weld the gear frame in
situ would seem to me to be total lunacy !
If this welding must indeed be done then the only safe and satisfactory way
of accomplishing this will be to remove the frame from the fuselage and to
dismantle and completely remove the retraction shaft, bushes and retraction
arms. Any attempt to weld the frame without dismantling the retraction
mechanism will probably damage the phosphor bronze bearings and almost
certainly vaporise all the grease which we had all carefully packed into the
bearings.
In my case I doubt whether my landing gear frame can be removed without
damaging the fuselage. Like many builders I reduxed it in believing that it
would never ever have to be removed. It would be impossible to simultaneously
heat all four attachment arms to soften the adhesive without damaging the
main fuselage structure. The only solution would be to saw the frame away
---From the four support arms and individually separate each one from the
fuselage. This would render the landing gear frame useless thereby requiring
someone to find the cost of a new one (presumably complete with mod 37).
If this mod really is necessary, (and I accept we are not qualified to say
whether it is or not), then a complete replacement of the frame would seem to
be the the ideal solution. Of course I have completely ignored the matter of
who would pay for such a program.
Whilst I do not doubt it is possible to weld the frame in situ I believe no
consideration has been given to the long term problems which this "fix" may
generate. I had always been led to believe that it was bad practice to
attempt to prematurely cool down welded joints with water (or other coolants)
due to the inevitable internal stresses in the metals which this will cause,
yet this will be unavoidable if the fuselage is not to catch fire during the
welding process.
If the frame is to be destressed properly it should be completely heated (to
a dull red temperature) and allowed to cool naturally. Clearly this would be
impossible without removing and dismantling it completely.
Having pondered the problem for the last few weeks I can see no reason why a
pair of bracing straps could not be made which would fulfil the same job as
the welded struts. I am aware that this was in fact Ivans first attempt to
resolve the problem. I would suggest two U shaped steel straps (about 1"
wide x 1/8" thick mild steel ) be passed around the bottom strut (swinging
arm axle). At the top, each of the four ends would have a 1/4' bolt welded to
each (tapered) end. These would be passed through a machined saddle piece.
attached to the top of the landing gear shaft housing. Four nuts (over the
1/4" bolts) would apply tension to the bracing straps.
This solution would do away with the need for builders to do any welding and
I believe would produce a much more satisfactory result.
Clearly, those who have not yet bonded in their frames can have them modified
in the normal (welded) manner.
I hope the factory (Ivan, Andy and others) will not file this genuine concern
of mine in their groans & moans file, and give it some serious thought. I
shall be faxing a copy direct to them on Monday. I appreciate they are trying
to make the best of what has turned out to be a bad job, but seriously guys,
this particular fix fills me with terror. Unless you can convince me
otherwise I am not at all happy about doing what you suggest. As many
builders will have not yet reached the frame attachment stage, you (the
factory) will not have to bin the mod kits already manufactured.
Hopefully my moan will elicit dozens of testimonials from satisfied builders
who have done this mod and lived to tell the tale. Perhaps I have
misunderstood what is involved and I'm making a mountain out of a molehill !
Regards
Carl P
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