Chris,

 

Very good point!

 

The ES Yahoo group has been very active in the last year dealing with damping of the nose strut.  There are two SBs on the strut, SB43 and SB57.  Lancair also has a new model strut with higher damping forces.  I believe it replaces the ESCO strut in the new kits.

 

One ES had a failure of the O ring and had a violent shimmy incident, requiring the pilot to roll out with minimal braking, keeping the weight off the nosewheel as long as possible, no damage to the aircraft, thankfully.  Since he's from Texas, I thought he deserved a big silver belt buckle for staying on for 8 seconds!  Afterwards, the strut was rebuilt at Lancair.  The found the torn O ring.  There have been two other ES shimmy incidents resulting in collapsed struts, bent props, engine teardowns.

 

Tim also has developed a modification that adds a second O ring, not sure when the modification was available, or whether it's done as standard procedure on struts returned to Lancair for rebuilding.

 

The ES seems to be more susceptible to shimmy, maybe due to the mass of the wheelpant or possibly the hot cowl air flowing down the strut fairing, heating the damping oil and lowering its viscosity.

 

There is a test where you take two sheets of metal with grease in between, located under the nosewheel and twist the nosewheel to check for dead spots in the damping force.  One of the SBs explains the procedure.

 

I second Chris's post, don't fool around with any leakage or shimmy, it could get very expensive!

 

Mike Easley

Colorado Springs