REFLECTOR: Another shimmy story...

[Andrew Ellzey]

Pat,

Is the damage from the Shimmy, or is the wear of your bolt and the nose gear 
strut pivot because there isn't any grease fittings installed to keep this 
nose gear retract pivot point properly lubricated. I have already installed 
my gear system and was disturbed with the lack of provisions to lube the 
system for the nose and the mains. As with everyone else I was in to big a 
hurry to see some progress with my build, to take the time to drill and tap 
all of the bushings to install grease fittings. But If your bolt and 
bushings have worn in this short of time I will probably take the time to go 
back and add a way to grease my gear. My 1964 Mooney's gear had a grease 
fitting at every pivot point and it had 0 wear after 40 years of use when I 
removed everything for complete strip and paint job in 2004. The gear only 
had to be lubed on the annual inspection.

Andy


----- Original Message ----- 
From: "Pat Shea" <xl340hp at yahoo.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Thursday, June 29, 2006 12:44 AM
Subject: REFLECTOR: Another shimmy story...


>I had 140 hrs on my XLRG without a hint of shimmy -
> until last weekend. I was landing at an airport with a
> relatively high density alt (6,500'), my mind was in
> the Bahama's, and I just botched the landing. I hit
> hard and the nose wheel bounced. I set the nose down
> real nice and easy the second time but it started to
> shimmy. Since a truly botched landing must also have a
> drift component, I suspect mine did and that caused my
> nose wheel was cocked off a little after the first
> hit. I immediately raised the nose and tried lowering
> it again - more shimmy. I pull the nose off again,
> adding power by now to go around, but the nose fell as
> the canard stopped flying - more shimmy. While
> accelerating at full power with aft stick, the shimmy
> stopped. Whew! Full stop.
>
> Each of the three shimmy events lasted about 2
> seconds. Up until this point, my landings have all
> been average or better, and The Big Nut on my nose
> wheel is always tight (over 15lbs of break out force).
>
> Post-mortem: There are significant rubber marks on the
> inside walls of my nose gear fork where the tire was
> rubbing during the shimmy (I have about 30 psi in my
> nose tire). There's a hairline crack around one of my
> knurled bushings. With the nose lifted into the air, I
> can grab the nose wheel and wiggle it side to side at
> least 1/4" (free play). The play is coming from the
> nose gear pivot bolt and the sleeve (on the strut) the
> bolt goes through. The tire, wheel, keel, and
> captivator are fine.
>
> I've ordered a new strut, pivot bolt, newer style
> bushings, and newer style bellville washers. In the
> aviation world, $300 is a small amount to pay for a
> botched anything. If this was a production plane,
> you'd have to add another zero to that number...
>
> Oh, and I ordered Ken's nose wheel locking system too.
>
> FWIW, Pat
>
>
>
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