Mailing List lml@lancaironline.net Message #56019
From: Dan Schaefer <dfs155@roadrunner.com>
Sender: <marv@lancaironline.net>
Subject: Re: LNC2 over-center link
Date: Mon, 16 Aug 2010 08:43:24 -0400
To: <lml@lancaironline.net>
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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