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hhart
rrApprentice San Jose, CA |
TREX 500XT Umbrella Gear Failure - Bearings Hi All,Just put together the Align 500XT combo kit. Maidened without any problem and on 15th flight, the flybarless was setup pretty well. On flight #28th, the tail went to pirouette un-controllably while I was inverted, and the XT was crashed in Hold mode.Upon close inspection post crash, I saw the umbrella head snapped off. When disassembled, it is obvious that the bearings that holding the umbrella gear seized up and the umbrella gear basically heated up and snapped.Below are the pictures, let me know what you guys think since not much news on the 500 size. ![]() ![]() ![]() ![]() |
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![]() rrKey Veteran Granbury, TX USA |
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hhart
rrApprentice San Jose, CA |
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gnichola
rrApprentice Santa Rosa, CA. USA |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/There is nothing to fix in the design.That umbrella gear is working like a fuse. So, the behavior is OK and it is doing its job.It is always more cheaper to replace this little thing that replace spur or something else.So, remember... When you have a crash, the mechanism needs a "fuse part" for safety reason./ |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/So, base on that fact, I recommend to have this little fellows in your tool box. ![]() ![]() |
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gnichola
rrApprentice Santa Rosa, CA. USA |
Secondarily, I don't think the bearings are slipping and causing heat, they are falling apart. Here is a shot of the one from the front end the tail. ![]() |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/Ok.. Ok... I got it!Your heli didn't hit the ground to cause the gear umbrella to break...Your were flying and suddenly, you lost tail control near the ground.This is a complete different analysis.According to your pics, the two bearing broke, got hotter, and then stuck.This two bearing are low profile and sometimes, it is difficult to install. This bearing are designed for radial forces. If you hit that bearing to put it in place, you can damaged because that bearings can't handle axial forces.So, IMO, the two bearings failed because someone hit it to installed on the umbrella gear. With time, the bearings begun to make sounds, get hotter and finally got stuck.And then, we know the rest of the tale...My recommendation is that when you install the new umbrella gear and the two bearing, be careful. The bearings must slip softly. If it is hard to install, use sand paper to shape the umbrella gear.PD :Use liquid grease ( for electric motor bearings) for the two bearing before instalation.There is a chance that the old bearings were not greased enough. It happens.../ |
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hhart
rrApprentice San Jose, CA |
hhart |
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