Dan,

 

Righto!  The only thing holding the main gear from collapsing outward is the over center link. Crosswind landings and takeoffs can certainly place a great deal of stress on those links.  By the time I had finished building my 320 in '96, Lancair made a new outboard link available with the rod end actually screwed into it.  I still have the old original ones in my "don't you ever use these parts" box.  I remember that it was hard to drill the rivet holes and go through the center of the rod end that slipped into the link. 

 

While folks may want to refer to replacement "steel", the actual links are made from some pretty tough alloy beyond simple aluminum.  Were I to have some sort of copy made I would try to find out what the alloy composition is.

 

Scott Krueger

 

Back in '93 when I was getting ready for my inspection and first flight of
my 235, my hangar mate who had taken off earlier in the week for Oshkosh,
showed up in the hangar with his wrecked L235 on a trailer. In Arizona a
main gear over-center link pulled apart on take-off (but before he had
flying speed) and he took out some runway lights with one of his wings -
plus a lot of other damage. On the early design, the steel fitting to which
the lower ball-end was attached was epoxied and riveted into the lower
aluminum link - and that's where the thing came apart.

When I saw where the failure had ocurred, I took my lower over-center links
to a machinist friend and had him make copies in steel with internal threads
for a short length of SS threaded rod for the connection to the female
threaded ball-end. (Incidentally, following that incident, I told Lancair
about what I had done and they immediately changed the design and made steel
links available - if you've been around Lancair long enough, you may
remember when that happened). I had the machinist make about a dozen pairs
and for a bunch of guys still using the original parts, and if I remember
correctly, they were about $100 per set. Small price to pay to eliminate
such a really bad potential failure mode - even if the cost was two or three
times that today.

I'm bringing this up to suggest that having a good machinist make copies of
your link parts, if you deem it necessary, shouldn't be such a big deal -
CAD drawings of no. I'm not a machinist but with the original part in hand,
a good machinist should be able to make an exact replica in whatever
material you want - or with whatever mods you think necessary - as I had
done, changing the bearing connection to a threaded insert vs. the smooth
bore hole which required glueing and riveting.

In my opinion, the nose gear link is no more complicated in design than the
main gear link so it shouldn't be all that difficult to copy.

Just my two cents worth.

Dan Schaefer
LNC-2   N235SP still flying (a lot) today.


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