Svein,
Would it be possible for you to post the actual specs of the spring
being manufacutred? If it is possible to closely match these specs, off
the shelf springs may be attainable more readily and at a reduced cost,
here in the US. Thanks in advance for any information you can render...
Jeff - N55XS
99.9 hours
Sidsel & Svein Johnsen wrote:
>
>Hi all,
>
>As I have already installed the Dutch designed/Dutch manufactured springs, I
>have
reflected on some of the information/suggestions on the forum today:
>
>- Risk of hooks making grooves on the tubes: Cannot be ruled out, of course,
but can only happen if the hooks rotate on the tubes. This requires that the
springs are stretched, which in turn means unusually hard nose wheel landings.
The flexibility of the tire and the nose gear arm takes the first part of
landing
impact loads. The springs begin to strecth only when a load of approx.
150 kg (310 lbs) is acting on the nose wheel, which is much, much more than
experienced
with normal trigear landings where the nose wheel touches gently during
roll-out.
>I do not think that square section wire is the way to go in order to increase
the contact area/decrease the risk of wear on the tubes. It will be very
difficult
to manufacture the spring so that a flat side lies squarely aginst both
the upper and the lower tube (or any of them, for that matter) in the actual
installation.
A sharp edge will be much worse for the tubes than a round cross
section.
>
>- Galvanic corrosion should not be of great concern here. Besides, except in
countries where IFR is permitted for Experimental class, dry runways will be the
norm. I would not be surprised if a plastic tube over the hooks for insulation
will yield quickly with the substantial pressure applied at a very small
contact area. Also note that the Dutch springs have hooks rounded to a diameter
corresponding very closely to the diameter of the upper and lower tubes (having
different diameter, too), so any plastic tube on the hooks will reduce the
diameter and therefore will easily be damaged just by installing them.
Increasing
the hook diameter to allow for a suitable insulation could of course be
done, but this must be done at manufacturing as the Ducth wire is 8 mm.
>
>Nevertheless, good points, both of them, and only time will tell for sure.
>Therefore,
these points warrant inspection along with all the other areas that must
be checked regularly.
>
>Regards,
>Svein
>A225 - now in Norway
>
>
>
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