Rowland,
1) I can't remember why, but I also ended up with the wheel contacting the
brake master cylinder and a rudder cable. I had to move one of the rudder
cable guides slightly, and as jon suggested I had to file back the up gate
slightly so the swing arm did not retract quite so far. As jon said, that
meant having to readjust the flap mechanism.
2) The geometry is complex, but as jon said I think the amount of
precompression of the rubber block is critical to getting the correct amount
of overcentre with the gear down, so the measurement specified in the manual
is important. Ron Parigoris has written a couple of nice emails on the list
concerning the geometry and the fact that on some u/c frames one or both of
the stops were not the correct length and needed filing back a little to
achieve the overcentre position. I seem to recall that there have been a
couple of expensive u/c collapses associated with inadequate overcentre or
slight undercentre positioning. The down gate is not strong enough to hold
the gear down if it is not overcentred against the stops.
Good luck !
Regards,
Keith.
-----Original Message-----
From: Rowland Carson
Sent: Saturday, June 06, 2015 9:47 PM
Subject: Europa-List: undercarriage retraction problem
Ive finally managed to satisfy myself that the flaps are operating over the
correct range, and moved on to installing the undercarriage. After fitting
the LG02 swinging arm to the LG01 mounting frame, I was still (just) able to
operate the retract lever without any bungee assistance. Then I fitted the
wheel and brake to LG02 and of course that made it too heavy to retract
without the bungee.
Yesterday I fitted the bungee and was pleased to find a number of loops and
tension that nicely balanced the weight of the undercarriage and allowed the
lever to operate quite easily. However, I couldnt quite get the lever into
the up gate. Examination of everything showed that (1) the tyre was
hitting the brake master cylinder and its elbow connexion and (2) the brake
slave cylinder was catching the rudder cable.
Initially it looked as if LG02 might be too far to starboard, but I had
taken care when fixing LG01 into the fuselage to have LG02 temporarily
fitted, and inserted packing to keep LG02 equidistant from the tunnel at
each side.
The other possibility that occurred to me was that (despite careful
measurements against the manual callout) Id pre-compressed the LG06
suspension block at bit too much, causing the distance between the LG08
pivots and the LG02 pivots to be too small, thus making the LG02 swinging
arm retract too far.
I tried backing off the M8 stiffnuts a little (which involved removing and
re-installing the bungee again - nobody mentioned how hard it is to thread
the bungee around LG02B anchor tube) and that did seem to allow a little but
more movement in the up direction but nowhere near enough to get the lever
into the up gate. While looking at everything after that adjustment, it
seems that the linkage is not quite going over-centre in the down
position - it appears the 3 pivots are just about in line with each other. I
wonder if lengthening the suspension assembly has caused that.
Can anyone suggest what I might be doing wrong, please, or any way to solve
the problem?
in friendship
Rowland
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