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sandpiper

nose landing gear polyurethane pucks

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Just completed my condition inspection and want to share what I found when I took the nose gear off the plane and disassembled.

About two weeks ago a shimmy began in the nose wheel when letting it down on landing roll out. My first thought was one or more balance weights had come off. That wasn't it.

Teardown revealed that one of the six pucks (the bottom one) had mostly disintegrated. Fortunately had new parts on hand so rebuilt it and balanced the wheel. All is good now. There was not any other damage nor were there any hard landings.

I installed the original pucks in March 2013 (328 hours) when I replaced the spring with the pucks. I have not taken it apart since then until now (723 hours). Although there is no requirement to take it apart provided external inspections check out, perhaps that was a mistake.

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The old red polyurethane dampeners used to be 20mm tall x 20mm wide. The new ones are 25mm (1") wide. These hold up and last much longer and less likely to fall apart. Plus in the maintenance manual it tells you how to check these in a quick easy way and is supposed to be done every annual, but since it is so easy and quick should be done every few flights. Just grab the prop up by the spinner on two blades. Lift the front end by about 2". Then set it down firmly. If there is ANY free play up or down and it is not firm then these need to be replaced. While the front is off the ground I take my foot and try and wiggle the front wheel left to right. If there is more than about 1/4" then the front suspension pin should be replaced. Failure to do this will cause the wobble to become worse and wears the slot the pin resides in to become wider. The more wobble this has the worse it will get and can get bad enough to rep[ace the front suspension. That said it can be fixed if necessary if the slots are too wide.

The old style spring which should have been removed many years ago was a major contributor of this slot wearing too wide because of all the travel it had. The red dampeners have very little movement.

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Thanks Roger. I have the oversize pin but did not need to use it. I also have the oversize pucks I got from you but once I had them on, I had trouble getting the nuts on. Not enough thread. So, used and extra set of smaller pucks I had from 2013 when I did the original conversion. Once I got the nuts on, and torqued, I could see there would be plenty of thread if I had used the bigger pucks.

At that point, having had to fight to get the smaller pucks installed, I decided just to leave it with the smaller pucks.

With the new pucks, and a rebalance, it's smooth as silk. If there is a next time, I will use the bigger pucks.

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Hi John,

Happy New Year to you and your wife too. Come on down anytime. In my new home I have tons or room and full hookups for your RV.

The red dampeners at times have to be pushed down just a tad to get the nut started. This is different on all CT's. Some nuts start easy and some you have to push down hard. That's mainly because the full length bolt down the center isn't adjusted the same in all CT's. So what I do is place the suspension on the ground with the opening for the nut facing straight up. This way I can use my weight to slightly compress the dampeners to get the nut started. Once started screwing it down is easy. One other way if it's too tight is to take the top red dampener and sand a little off of it to make it shorter and easier to start the nut.

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