- Joined
- Oct 31, 1996
- Posts
- 707
- Type aircraft owned
- Carbon Cub FX-3
- Base airport
- KFCI
- Ratings
- COMM, IFR, MEL, SEL
Recently I had issues with tailwheel shimmy and I'm interested in how others mitigate this issue in taildragger aircraft. It seems the changes I've made improved the situation but I will continue to monitor. First off I haven't raised the tail and inspected the tailwheel assembly since I brought the Carbon Cub FX-3 home in October of 2021. I saw a video from Trent Palmer during his condition inspection where he found a mounting bracket cracked and needing welding on his Kitfox. I bought this up during my condition inspection where I did an owner assisted in May of 2022 yet it wasn't inspected. Fast forward to dealing with tailwheel shimmy issues it was time to raise the tail and inspect.
First I found my ABI 3200 assembly was loose which connects to the Airframes Alaska T-3 tailwheel shock assembly. As fellow FX-3 owners decided to inspect theirs we weren't sure what the torque spec was supposed to be on this 5.8" bolt but learned 45 ft-lbs was the spec. Several found their around 25-30 ft-lbs and hence re-torqued their bolts. I also made a few other adjustments after talking with Airframes Alaska about the T-3 and also shimmy mitigation on the ABI-3200 so I get the T-3 properly configured as well.
A friend told me some time back he too had this issue on his SS and using a higher tire pressure helped so I'm using 55 psi as my target now on the standard 3200 tailwheel (not baby bushwheel). The other two adjustments I found was a tension bolt that adjusts the pivot of the 3200 rotation friction and tightened that slightly which I think is a big help but also removing a link on the steering arm chain so there is more support to stabilize the tailwheel at first touchdown. Some suggested it should be slack in the centered position but I'm finding that may be causing a shimmy condition.
With the adjustments mentioned above so far so good but I'm certainly monitoring the situation. Here are two recent videos I did where I bring some of these topics up if you care to watch. I'd love to hear from others as to whether shimmy is normal and any recommended steps to mitigate when required.
First I found my ABI 3200 assembly was loose which connects to the Airframes Alaska T-3 tailwheel shock assembly. As fellow FX-3 owners decided to inspect theirs we weren't sure what the torque spec was supposed to be on this 5.8" bolt but learned 45 ft-lbs was the spec. Several found their around 25-30 ft-lbs and hence re-torqued their bolts. I also made a few other adjustments after talking with Airframes Alaska about the T-3 and also shimmy mitigation on the ABI-3200 so I get the T-3 properly configured as well.
A friend told me some time back he too had this issue on his SS and using a higher tire pressure helped so I'm using 55 psi as my target now on the standard 3200 tailwheel (not baby bushwheel). The other two adjustments I found was a tension bolt that adjusts the pivot of the 3200 rotation friction and tightened that slightly which I think is a big help but also removing a link on the steering arm chain so there is more support to stabilize the tailwheel at first touchdown. Some suggested it should be slack in the centered position but I'm finding that may be causing a shimmy condition.
With the adjustments mentioned above so far so good but I'm certainly monitoring the situation. Here are two recent videos I did where I bring some of these topics up if you care to watch. I'd love to hear from others as to whether shimmy is normal and any recommended steps to mitigate when required.
