fatigue crack and break of tail wheel spring

[n502pd]

Update: I didnt want to continue the other string with the update on my problems with the Ti rod tailwheel spring.
I did replace the Ti rod with one from Sonex, and have done one flight on it since install. All appears well. However there is still just a bit of slop at the aft end of the mount, as there was with the first rod. I did however, identify a small, 1/2 pin head sized dot of metal in the approximate location of the fatigue crack that initiated the failure. I took great care to remove the greatest amount without enlarging the opening more that it was already. I did add a piece of spring steel shim into the opening for about 3/4 inch ( that was as far as I could get it without destroying it) in an attempt to reduce the play. I could not elliminate it fully. I am back flying and attempting to also master my flare at landing!! Thanks to all for all the assistance with this. I did learn stuff!!!:)

[WaiexN143NM]

Hi joe,
Peter anson has come up with a new tailwheel bracket and rod. Check into this if you have any more trouble. Let us know how it goes. So far our waiex 150 hrs no problems. Some have added shims or glue.

Peter has some great upgrade sonex/waiex/xenos/onex products.

Good to hear your having fun.
Cheers,

WaiexN143NM
Michael

[DCASonex]

If you can find an appropriate reamer, run it into the sockets for the rod, both top and bottom. Due to welding and paint, both are a bit out of round and inconsistent ID. You can then wrap both ends of the spring rod with thin SS shim stock full length of sockets. multiple layers of thin (0.004" or less) shim stock are easier to work with than one thick layer.

David A.

[n502pd]

Hi joe,
Peter anson has come up with a new tailwheel bracket and rod. Check into this if you have any more trouble. Let us know how it goes. So far our waiex 150 hrs no problems. Some have added shims or glue.

Peter has some great upgrade sonex/waiex/xenos/onex products.

Good to hear your having fun.
Cheers,

WaiexN143NM
Michael

thanks for the info! I, as others at the airport , are asking what is next if the grass field I fly from ( and maybe my learning curve/) cause another breakage. I will definately look into Peters items!

[n502pd]

If you can find an appropriate reamer, run it into the sockets for the rod, both top and bottom. Due to welding and paint, both are a bit out of round and inconsistent ID. You can then wrap both ends of the spring rod with thin SS shim stock full length of sockets. multiple layers of thin (0.004" or less) shim stock are easier to work with than one thick layer.

David A.

That is the idea I sort of came up with too. But, the reamer has been a problem. And, as I remember from the MLG leg bolts, as specified on early plans, stainless bolts were used. If my memory works this morning, I remember stainless and titanium are not compatable? The small shim I used was spring steel from a feeler gauge (tested with a magnet) verrified as steel. And I still have a tiny bit of play. I am not really done with this problem yet, and if you know of a source for an adjustable reamer suitable for steel that wont cost arms and legs, I would be greatful for the info. Before much more time is flown off, I will look at Peters items too.

As a side question, has anyone utilized the redesigned tail rod and mount, and what are your thoughts?

Thanks everyone for the help!!

[Bryan Cotton]

I've only bought his NACA vents and tailwheel steering push rod. My impression is that his products are good and his engineering skills are solid.

[Darick]

HI Joe, I have the larger Sonex tailwheel design and I'm at a grass runway. So far, I've only taxied a little bit. Looks like hurricane Nate will prevent a first flight this week and who knows how long for the runway to dry out. I'll try to remember to give an update on the tailwheel....or were you talking about Peter Anson's tailwheel?

[DCASonex]

If memory is correct, Stainless Steel bolts were originally used on landing gear legs since it was thought that Cadmium would react with Titanium. However when those bolts were found to be breaking Sonex switched to conventional cad plated AN bolts with higher strength than SS. Think the Cadmium Titanium reaction problem only occurred when heated. So long story short, should not be any problem with SS and titanium.

David A.

[SonexFactoryTech]

If memory is correct, Stainless Steel bolts were originally used on landing gear legs since it was thought that Cadmium would react with Titanium. However when those bolts were found to be breaking Sonex switched to conventional cad plated AN bolts with higher strength than SS.

This statement is incorrect. Cadmium bolts were breaking (three different airplanes at one airfield in a short period of time) because they were being overtightened, stretched in tension, and therefore weakened in shear. The change was not made because of bolt material, it was made because of bolt STYLE. By switching to drilled bolts secured with castle nuts we hoped to reduce the mindset of "if tight is good, tighter must be better." It was that mindset that broke the bolts, not the material of the bolts. The original stainless steel bolts are still acceptable if installed correctly, and the new cadmium bolts can still fail if installed incorrectly.

Blue Skies....

Kerry Fores
Technical Support Manager
Sonex Aircraft, LLC

[n502pd]

HI Joe, I have the larger Sonex tailwheel design and I'm at a grass runway. So far, I've only taxied a little bit. Looks like hurricane Nate will prevent a first flight this week and who knows how long for the runway to dry out. I'll try to remember to give an update on the tailwheel....or were you talking about Peter Anson's tailwheel?

I have an alternatively procurred(??) 6 inch wheel anda copy of others wheel pivot that is working very well. I dont have any precieved problems with those items. I am only mildly concerned that I have gotten all the hot points removed inside the mount that probably had caused the fatigue crack to begin with. My next thing is to shim more completely as I am not fully satisfied with the small bit of play left from initial shimming.I have looked at Peters TW, but I feel I am not in need of his ...yet! I am just at almost 7 hrs into testing. My landings are a bit fast still until I can get the 'magic number' for over the fence speed firmly in hand, if you know what I mean! I am sure that extra speed, and jitteriness on the flair are causing extra working of the TW spring.
TKS!