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Broke my tailwheel spring :-{

PostPosted: Wed Oct 29, 2014 4:55 pm
by alan
I have had several instances of tailwheel shimmy upon landing. Not every landing, just sometimes. My wife and I loaded up the Highlander with camping "stuff" and flew up to Reklaw last weekend. The landing was normal but the tailwheel shimmied again when it touched down. We stopped faster than normal and veered to the right. Those lined up watching barely had time to start to scatter when we stopped. To make a long story short, several guys helped me move across the runway and tie down. Monday my buddy Mack and I drove back up and loaded the poor crippled bird onto a trailer and drove, slowly, back home, a distance of 185 miles. Today the tailwheel spring stub is off as well as the bent rudder. A new spring and rudder horn have shipped from Just, covering supplies are on order from AC Spruce, the rudder has been stripped of fabric and marked for modification so it maybe won't contact the ground if this happens again. Of course the major contact point of the rudder was the tailwheel assembly, but I can't do anything about that.

My thoughts are that the spring had been cracked for some time, based on the attached pictures and several experts, and had been slowly bending. This changed the castor of the pivot point so that the shimmy could occur. Also, this time there was more weight in the back than on any previous flight. I was able to trim hands off, so CG was still in, but even though the tailwheel touch down was gentle it moved the castor even more to the "Dark Side" and the rest is history. Dang.

I'm sure the reason it cracked to begin with had something to do with several of my past landings. You know, wacking it down on the odd piece of driftwood on the beach, and touching down tailwheel first several times going for short field landings. Ya gotta love that Highlander. I know I do.

Alan

The two grinning guys posing beside my Highlander are Dave Mason, the host of the Reklaw Fly-In, and Mack Graves my flying buddy.

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 1:43 am
by taildrgfun
I've broken a couple of those too over the years. I like my rudder to taper up 6" to prevent damage in case of a TW problem. I also think the TW spring should be replaced every so often before they break. It is usually a matter of when they will break, not if they will break.

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 8:33 am
by User GDS
That picture of the rudder looks very familiar... When I repaired mine I took Steve Henry's suggestion and changed the line on the bottom of the rudder so the TW won't hit it. I doubled the tailwheel spring, too, and I really like it.

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 12:12 pm
by Tralika
This sounds familiar, not sure if that means it's a trend but it's starting to look like one. Back in May I started a discussion titled "Twisted Tail Wheel Spring". Several folks chimed including Gil T who had a similar broken tail wheel spring incident. This was posted by messenger;

Re: Twisted Tail Wheel Spring
Postby messenger ยป Wed May 14, 2014 11:01 am
I also use a double tailwheel spring, Boise spring works in Boise, Idaho made mine. It takes a lot of the bounce out of the tailwheel on a hard landing. R L Messenger

I'm thinking I'll replace my stock tail wheel spring with a double spring. I'll give Boise Springs Works a call and see if they still have the pattern.

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 3:49 pm
by Gil T
This all sounds familiar. My spring broke right at the bend. I suspect that the bracket that I had Ted Sutton weld on at the rudder post put the stress point right there. However, I was concerned about the amount of wiggle that the spring had setting in that channel. I suppose the fix for that would have been to grind a little off of the sides of the spring. From looking at many different tail-draggers, I think most of them have a similar arrangement. I think I would like to try a double spring. It might not be quite as stiff. The large rock that took out my last tail wheel might have been too much for most wheels. My present spring is 3/8 inches thick. With the double spring do you use 2 3/16 inch springs? And does your source drill the holes that are needed? And lastly, how much does it cost?

Gil T

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 8:20 pm
by User GDS
Hey Gil, I scrounged my second tailwheel spring, it's off of my friend's Aeronca Chief and the hole and bend fit perfectly to the spring I got from JA. I'm going to call these guys to see if they can make me a spare double spring set, I'll let you know the $$.

http://www.atlassuspension.com/atlas-tech.html

Re: Broke my tailwheel spring :-{

PostPosted: Thu Oct 30, 2014 9:26 pm
by gkremers
Gary,
Let me know the cost also, I may want one just in case.

Thanks
Gary

Re: Broke my tailwheel spring :-{

PostPosted: Mon Nov 03, 2014 5:12 pm
by alan
Update.

Was looking at the tailwheel attachment area while removing the old bolt and noticed the fabric was cracking in the area. After looking inside with my finger and then a mirror I found this.

It looks like it might have been cracked for a little while but it couldn't have been too long as I was able to move it some with just one hand. If it had been cracked for any length of time it would have bent the rudder post and support tubes. There was some dirt and a mud dobber nest back there which might explain the "aged" look of the area.

Could someone post a picture of a new kit, uncovered of course, focused on this area so I can compare my 9 year old airplane with the latest Highlander structure?

Thank you.

Re: Broke my tailwheel spring :-{

PostPosted: Mon Nov 03, 2014 8:12 pm
by Tralika
Alan,
Sorry to hear that your issue got worse. Here are a few photos of my Highlander. Note that this is sn #191, built about 5 years ago. It looks identical to your airframe, I don't think Just made any changes to the Highlander airframe. Maybe Jak will chime in here and confirm that. Based on what your plane looks like, I think I'll make sure I have an inspection hole that will allow me to get a look at that part of the structure. Let me know if you need any other photos of my airframe.

Re: Broke my tailwheel spring :-{

PostPosted: Mon Nov 03, 2014 9:19 pm
by jak
There was a change but I don't know at what serial # it went into efect. What we did was to make the to lower longerons sleved at the tail end with larger tubing. the ones we have fixed we sleved with a larger tube and put on a new tail wheel spring perch. Jak

Re: Broke my tailwheel spring :-{

PostPosted: Mon Nov 03, 2014 10:56 pm
by taildrgfun
It looks to me like you had tailwheel shimmy some point. That will cause damage in that area for sure.

Re: Broke my tailwheel spring :-{

PostPosted: Tue Nov 04, 2014 12:40 am
by SheepdogRD
Here are the reinforced lower tubes. This picture was taken at the factory in late February 2014.

Highlander Fuselage - Rear.jpg

Our kit is #228. It shipped in early 2011, and it has the reinforcements.

Re: Broke my tailwheel spring :-{

PostPosted: Tue Nov 04, 2014 1:24 pm
by alan
Thank you John, Jak, Steve, & Richard. The provided pictures and info were quite helpful. I have had some shimmy problems, but not for very long. It could have caused or resulted from the cracks. Who knows? We are going to reinforce the area around and forward of the cracks in an effort to spread the stress out. Photos to follow.

Thanks again.

Alan

Re: Broke my tailwheel spring :-{

PostPosted: Tue Nov 04, 2014 1:59 pm
by Tralika
My airframe has the same reinforcements. The longerons are 1/2" tube, the last couple of feet is 5/8".

Re: Broke my tailwheel spring :-{

PostPosted: Wed Nov 05, 2014 11:29 am
by alan
We're going to add some gussets and extend the bottom plate forward and add an inside plate as well. I like that additional bracket on Gil's airplane. Sleeving is just way too much work what with the required deconstruction and reconstruction required. It will be much stronger when we are finished.

Pictures and details coming soon.