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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