lml@lancaironline.net Mailing List Archive

Jim,

Since you have done all the logical things without effect, I'm wondering if there isn't something "built-in" that is causing the problem, like geometry. The only geometry issue I can think of is the strut rake angle. The correct angle was the subject of some debate a while back. All I know is that I set mine at +1.5 degrees (lower end forward) and I have never had a trace of shimmy. The previous discussion, as I recall didn't result in a definitive answer, but 0 to +1.5 or so seemed to be the "correct" rake angle. I have the rebuilt strut since new and have a different engine mount (for a Lycoming) and either of those might make a difference, although I'm pretty sure my engine mount is not more rigid than the standard one. While my strut is not held laterally any better it is probably more rigid in the fore-and-aft direction because of the different drag link design.

Gary Casey

ES #157

hotmail.com>
Date: August 24, 2007 1:52:50 PM PDT
To: lml@lancaironline.net
Subject: ES Strut issues

I have just finished the annual on my Super ES.

I discovered a cracked engine mount within ten minutes of starting the inspection.

I have experienced the "ES Shake" since the plane was new. It now has about 860 hours on it. I have done various things to the plane to address the problem through the years I have been flying it. Some things seem to improve it, some don't make a difference. The plane has never been without the shake completely. The shake occurs at the same speed (30-32 knots) on rollout after landing and while on the brakes. Releasing brake pressure makes the shake go away.

The following is a list of what I did the the plane during this annual, and had done previously, to help or eliminate the shake:

-Strut rebuild and update by Lancair (second time)

-Engine mount repair, update, reinforcement, inspection by Lancair

-New Cleveland brake discs

-Balance all tires and wheels

-Balance nose wheel pant

-Precisely align main gear both in toe and camber.

-Shim main gear legs to reduce "play" between leg and mount.

-Shim spindles to fit tightly to the gear legs

Test flight showed no noticeable improvement in the shake.

Jim Scales

Angel's Playmate