Art,

 

I hesitate to post my experience as I am not an approved ESCO repair/overhaul facility.  But here goes anyway. 

 

My ES had developed a very minor shimmy.  Inspection showed no cracks in the mount that all the bolts were tight, so I decided to disassemble the strut and inspect the mechanism for damage/wear.  I only have 140 hrs on the airframe, so I rationalized that it shouldn't have very much, if any, wear.  Since I have my own nitrogen bottle and manifold, I was confident that I could reassemble and recharge it. 

 

Upon removal of the strut from the mount, I noticed that one of the spring clips had come off.  While the mounting plates are captivated by the motor mount, I thought that this was interesting.  I also noticed that there was approx. 1/16" gap between the two strut mounting plates and the motor mount. 

 

Upon disassembly of the strutt, I noticed that the oil wasn't clear as I expected, but kind of milky-grey in color.  Other than that, I didn't find anything that looked wrong.  O-rings were all in good shape, etc.  So, I cleaned it up and reassembled it, replacing the old oil with fresh BelRay 30W fork oil.

 

I fabricated a 1/16" shim, replaced the snap ring, and reassembled everything, including recharging the strut with nitorgen.  

 

I then tested it on a greased plate and I could tell that the damping was significantly improved.  A few touch and go's proved that the problem had been corrected. 

 

What did I do to fix the shimmy?  I really can't say.  My guess is the fork oil was contaminated. 

 

Mark S.