- Joined
- Jun 27, 2007
- Messages
- 2,338
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So have had nothing but praise for my tailwheel which is a single fork Aviation Products with 4" solid wheel on a 5/8" rod spring. However, over the last several month maybe longer I have noticed that it will unlock on me if I'm turning slightly and hit a crack (bump) or if I am taxing with a brisk tailwind (elevator down too) but always to the the left. I have more than once now ended up in a very slow speed half ground loop. I have messed with it over the months but couldn't seem to figure out the problem so I re-assemble it and go on my merry way and several flights later while taxiing it would unlock on my unsuspectingly. It was really starting to piss me off but I could never figure out what was wrong. This past friday I was taxing out and it did it again and this time I was able to get it do it just by moving the rudder on my plane with my hand but it never unlocked to the right.
I disassembled it yet again this time looking for wear at the detent cam and I guess there may be some slight wear but nothing to write home about, but just incase I flipped the control arm over but this time I noticed some vertical slop where the control arm sits and allows some fore and aft PIVOT and some left and right PIVOT (see photo). It is ever so slight but what I noticed that the cam could work its way half way down so it only half engaged with the control arm. And all the other slop allows it to unlock (not sure why only one way though, maybe the single fork dynamics?) At any rate the washer that is under the nut doesn't sandwich the control arm because it is the same diameter as threads but the tail wheel post is quite a bit bigger so tightening the nut doesn't do anything. SO with the nut fully tighten there there is about 0.032 gap of freedom. I'm not sure If there is supposed to be shim there or a larger washer that ID is the same as the tail post but I decided to install a 0.032 aluminum shim that I made on the spot. I put the nut back on made sure the tail wheel would caster and flew it. I was shocked at the much better control I had on the ground and the thing never unlocked on my even when taxing around the corner with the bump near my hangar.
I will call APi on monday to see if my "bush" fix was necessary or to see if i'm missing a washer or something but I didn't see any other way to keep the cam fully engaged in control arm while within the locking range.
I disassembled it yet again this time looking for wear at the detent cam and I guess there may be some slight wear but nothing to write home about, but just incase I flipped the control arm over but this time I noticed some vertical slop where the control arm sits and allows some fore and aft PIVOT and some left and right PIVOT (see photo). It is ever so slight but what I noticed that the cam could work its way half way down so it only half engaged with the control arm. And all the other slop allows it to unlock (not sure why only one way though, maybe the single fork dynamics?) At any rate the washer that is under the nut doesn't sandwich the control arm because it is the same diameter as threads but the tail wheel post is quite a bit bigger so tightening the nut doesn't do anything. SO with the nut fully tighten there there is about 0.032 gap of freedom. I'm not sure If there is supposed to be shim there or a larger washer that ID is the same as the tail post but I decided to install a 0.032 aluminum shim that I made on the spot. I put the nut back on made sure the tail wheel would caster and flew it. I was shocked at the much better control I had on the ground and the thing never unlocked on my even when taxing around the corner with the bump near my hangar.
I will call APi on monday to see if my "bush" fix was necessary or to see if i'm missing a washer or something but I didn't see any other way to keep the cam fully engaged in control arm while within the locking range.
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