Skippydiesel wrote:Rofomoto wrote:Just landed at home airport, as I turned off runway bolt broke and gear spins in mount. Easy fix with only wheel pant damage but going to change all gear bolts at each condition inspection.
Hi Bryan - please elaborate what/which bolt (s) is this? Photo/sketch might help.
Bryan Cotton wrote:Skippydiesel wrote:Rofomoto wrote:Just landed at home airport, as I turned off runway bolt broke and gear spins in mount. Easy fix with only wheel pant damage but going to change all gear bolts at each condition inspection.
Hi Bryan - please elaborate what/which bolt (s) is this? Photo/sketch might help.
That was Billy's post. I assume it is the bolt that goes through the top of the gear leg in the motor mount. Others have busted this bolt before. Sometimes just one side and they find it during maintenance.
Skippydiesel wrote:My apologies Billy/Bryan - would still like an image or two to clarify where the problem(s) occurred.
mccool wrote:It was my understanding that Cad plated bolts should not be used in the Titanium gear legs
GraemeSmith wrote:Skippydiesel wrote:My apologies Billy/Bryan - would still like an image or two to clarify where the problem(s) occurred.
If you see this post in the Sonex Forum on FB You can see Day 5 of my just finished Condition Inspection where I cover replacement of those top bolts (with pictures). Pretty sure those are the ones they are talking about.
https://www.facebook.com/photo/?fbid=10 ... 3445473443
Kai wrote:We have had some experience with broken upper gear leg bolts up here as well. When this happened the first times, we stuck to the SB and replaced the stainless bolts with AN types. In addition, we safetied the bolts in such a way that the lower part of a broken bolt could not fall out (for some reason the bolts always seem to break in the middle). This would bar the titanium leg from rotating and cause a calamity.
However, the problem persisted as discovered during periodic maintenance. It appeared that the suggested 1/4 inch bolts just could not handle the torque loads imposed on the gear legs by the wheel geometry. What we then did was to ream out the upper holes in gear leg and engine mount to 5/16 inch (8mm), and replace the AN4 with Unbrako 12.9 class bolts and long nuts. The whole assembly was torqued up to a considerable pre load on the bolts (12.9 class bolts are extrmely strong!)
After this, the issue went away, and we have been flying happily the last years. Remains the question why the original bolts would break in the first place. We can only speculate that for some reason we could not get the wheel geometry aligned exactly to plans, and that his imposed excessive loads on the bolts.
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