Greetings,
Having suffered an undercarriage collapse during the takeoff roll on my
monowheel, I am now pondering what corrective actions to take to prevent a
re-ocurrence. As far as I can figure out, the overcentre locking went 'under
centre' when the aircraft went over a large 'ski-jump undulation' at just
below flying speed on takeoff from a grass strip. Having spent a lot of time
and money cleaning up the mess and fitting a new prop etc, I'm reluctant to
go flying again, even if I confine my operations to an absolutely
glass-smooth runway, until I understand why it happened in the first place
and have some degree of confidence that it won't happen again.
I've looked for any possible 'builder variations' in this area to see if
there is anything that I could have screwed up, but it seems that the
geometry in this area is totally determined by the manufacture of the
landing gear frame and the u/c components, what's more, this area has been
rigorously inspected on several occasions by some very fastidious
inspectors. (although my landing gear frame was modified in the factory to
add reinforcing following some very early landing frame failures, it's
possible that the geometry was affected during this mod). Are any other mono
owners aware of the amount of overcentre on their installations, it would be
interesting to see if there is much variation.
On my aircraft, the degree of overcentre in the 'down and locked' position
is 1/64 of hardly anything at all, (i.e. very small) and it occurs to me
that shaving a few mm off the stops on the landing gear frame would be a
good way of increasing the security of the overcentre locking.
Question: has anyone tried this? Can anyone think of a reason why not?
Regards,
Graeme Smith
No 26
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