Hi, I was very sorry to read of your misfortune. It must be heartbreaking.
With
luck the damage to your lovely looking plane will be just the retract handle,
strut mod and a new guide plate. (Engines and props are just bolt on
accessories!!)
Just a few thoughts from me: As the retract handle is still in the "down gate"
the over-centre locking mechanism has obviously failed to do it's job and has
let go for whatever reason. Certainly this should not be able to happen so I
feel it must be considered that something was not quite right with your set up.
It may or may not be possible to determine now what it was but either way
I'm sure that when you repair and check things it will definitely be possible
to avoid it happening again.
I believe that during the initial build (and in the uk, at each annual
inspection)
there are two critical considerations:
1/ The geometry of the set up must be correct.
2/ There must be no wear or play in any of the system which might allow this
otherwise
correct geometry to alter.
Nb. The following must be finally checked with no weight on the wheel, ie.
aircraft
hoisted.
1/ Geometry:
(a) The LG8 arms must contact their respective stops together and be parallel to
each other. Furthermore when the arms are on their stops the front edge of
the retract lever must be hard against the front edge of the "down gate" on
which
it reacts. The lever holds the arms against their stops so there must be
no gap here whatsoever, just a tight sliding fit so that you can actually move
the lever laterally in and out of the gate. If there were to be any gap here
then any vibration in the system could cause the lever to move forward slightly
thus partially retracting the undercarriage and bringing the "over-centreness"
of the lock to a critical point where it might go past the point of no return
and collapse. If it was to go past that point with the weight of the aircraft
on the wheel then nothing will save it!
(b) Furthermore, with the gear down and locked, the amount of over-centre must
be checked to be correct. An accurate method of sighting up (the centres) must
be devised. The middle pivot point (top reaction plate clevis pins) must be
min 1/16' and max 1/8' forward of the top pivot point (LG8 mounting shaft) and
bottom pivot point (LG04 pin). Too much puts extra strain on the LG frame,
too little and the over-centre lock would be critically 'weak'. To achieve this
the LG8 stops must be the correct length. They 'should' be correct from
manufacture
but I have heard of some people having to grind them down a bit and/
or adding to the length to get the amount of over-centre spot on. Finally the
pre-tension of the rubber block must be set correctly to achieve the correct
result (79mm between inner faces of the top and bottom reaction plates).
2/ Wear: Any wear or play anywhere in the system could cause movement which
might
critically affect the geometry, possibly allowing the over-centre to become
critical and collapse.
Namely, wear in any of the pivot points and bushes, wear/ slop developing in the
joint between the retraction handle and the port LG8 allowing unwanted movement
of the handle relative to the gear (though I notice you have the strut mod
so this should have been ok.) etc.
Could it possibly have been that on yours you may have had some gap at the front
of the gear handle, or maybe the LG8 stops were slightly too long thus not
giving
a safe amount of over-centre? These seem to me to be the most likely causes.
I'm not opening the oft-argued debate about which version of the Europa is best
again. (Monowheel IS the best one!!!!!!)
Good luck and Regards, Jon
--------
G-TERN
Classic Mono
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