Ron,
Thanks very much for the info and your experience with the over centre
locking -- very valuable!
When I say I measured the overcentre, I really meant that I eyeballed it by
sighting along the centres. It was over centre but only by a very small
amount (maybe 1/16"). There is nothing in the manual to say how much past
centre it should be. You say Andy said 1/8" would be the limit, that's good
to know. I have now ground away the stops, another constraint is contact
between the LG08P and the LG mounting frame. There is a scalloped area in
LG08P to provide clearance against the frame, removing more than a couple of
mm from the stops quickly brings LG08P very close to the frame.
I don't understand the bit about overloading the landing gear frame, surely
this must be designed to take the full landing load which would mostly pass
through the reaction plates to the stops, with some load being taken by the
top attach point on the LG frame??
Regards,
Graeme
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of
rparigor@suffolk.lib.ny.us
Sent: 23 February 2007 23:40
Subject: Re: Europa-List: Undercarriage Overcentre Locking
Hello Graeme
I am not flying my XS mono yet (A-265 picked up April 2003). When building
I mounted my gear on a fixture and was able to study and fool with till I
was satisfied I fully understood it's operation.
First off you said you measured the over center, how did you measure it?
First off you need to make sure that the rubber spring block is compressed
to proper dimension. The more you tighten, the more overcentre you will
see. If for some reason the gap becomes less than called out for, you will
start ooching towards undercentre. I used a thin straight edge resting on
the edge of 3 pins that are the same diameter. The top pin is the pivot
pin that attaches to LG08s, the bottom pin is LG04, and the middle pin is
a little tricky, I made an insert that fits in the middle of LG08 tube
with a pin protruding the same size as the prior 2 mentioned. Now I have 3
points and can measure overcentre.
To my horror, 1 side was under centre and the other just bout neutral! I
ground down stops to where there was just a tad over 1/16" overcentre. You
need to be very careful you don't over do this as it will begin to put
much stress on UCMF. I forget the exact number that Andy said, but perhaps
1/8" was the limit.
The top of stop was gone when I achieved 1/16" on 1 side and the other
side was paper thin. What I did was grind down to 1/8" overcentre, and
inserted with Redux/Flox a pretty hard and stiff piece of polyurethane I
got from McMaster Carr, and pinned it after cure with a bolt. The
overcentre is just a tad over 1/16" on the polyurethane. Andy gave my
kluge a thumbs up.
Please don't overlook the connection between LG08P and the retraction
lever. I was careful to ream these 3 holes and scuff sand and Redux this
joint, and installed the mod that reinforces this connection as well. If
this joint has any movement when the lever is in the down and locked
position, it may not be ramming and jamming the LG08s against the UCMF
stops.
I also made a spring return for the down stop lock where it is very
positive in keeping it where you want it.
Once all was assembled on aircraft, the stops were not hitting absolute
the same time. Splitting hairs here, but I put a piece or 2 of some
Stainless Steel tape as a shim. You can get small pieces of that tape from
Lockwood Aviation, they sell it as prop lead edge tape, or
www.mcmaster.com sells it by the roll.
Hope this helps.
Ron Parigoris
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