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Old 10-09-2006, 07:58 PM   #1
Gyan
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Default Bumpy Thrust Bearing Race

I took apart my tail rotor grip thrust bearings to find that the races were bumpy. The chrome isn't pitted there is just small dents around the race. This exists on all 4 races, Could this cause the pitch mechanism to jamb during foward flight but not during hover??? Luckily I have 3 intrepids & was able to swap tail rotors hub, grips & blades & the problem went away. So the problem is definately in the hub, grip area of the tail rotor. So far that's all I could find. Seems to be a small issue to cause a flight failure.
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Old 10-09-2006, 10:06 PM   #2
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Will most definitly cause tail failure. It can be intermitent at times. Good you took them apart, hard to tell otherwise.
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Old 10-10-2006, 04:45 AM   #3
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Chris showed me that trick for preflights. Holding both grips while pulling outward, rotate the grips. If the races have been damaged, you will feel those bumps. Normal thrust bearings feel smooth when checked, of course.

And, yes, that damage to the races will definately give you fits with tail control as the servo tries to over come that drag. When up to speed, the tension on the thrust bearings effectively turns those divots in stops. I can't imagine it's too good for your tail servo either.
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Old 10-10-2006, 05:10 AM   #4
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I think that the aluminum blades I had on it just made the problem worse due to them being a little heavier than the stock plastic ones! Funny how you can make a problem worse when trying to correct it, when your not sure of the issue! Thanks for your help guys new thrust bearings are next on the order list.
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Old 10-10-2006, 07:17 AM   #5
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Aluminum Blades?!?!? What aluminum blades?

It's funny how you hear about these things AFTER there has been some other problem....
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Old 10-10-2006, 11:21 AM   #6
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Quote:
Aluminum Blades?!?!? What aluminum blades?
I'm curious about that too.
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Old 10-10-2006, 11:33 AM   #7
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Well were all going to have to wait on the type of Aluminum tail blades they are...I bought them off a club member ....who got them from another club member. who is now in Europe. When he gets back I'll let you guys know.
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Old 10-10-2006, 11:34 AM   #8
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Would you like me to post a picture of them?
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Old 10-10-2006, 11:39 AM   #9
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I think it is more a curiosity thing...as aluminum blades are illegal to use in the US!
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Old 10-10-2006, 12:11 PM   #10
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...and your OK with carbon fiber?? :?: Seems the safety issues would be more extensive with carbon pieces flying around. But I bet aluminum main blades would really thrash the machine while doing the dreaded chicken dance. At least these are just small tail blades. The club member that originally had these tail blades has a turbine using aluminum mains. ( I think they come from europe)
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Old 10-10-2006, 02:31 PM   #11
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The problem with aluminum is the fatigue factor. Composite materials do not have a fatigue life like aluminum does.

I had actually hoped that there was some typo, that you meant aluminum blade GRIPS....

We do not and can not recommend EVER the use of aluminum rotor blades, tail or otherwise.
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Old 10-10-2006, 02:44 PM   #12
Gyan
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Trust me on this. They will be bent outa shape waYYYYYYYYY earlier than their fatigued life!!
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Old 10-10-2006, 04:50 PM   #13
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I was going to say something, but nevermind...
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Old 10-10-2006, 10:15 PM   #14
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OK, I'll believe you on that one!!

How much do these blades weigh?
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Old 10-11-2006, 07:52 PM   #15
Gyan
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Chris; They weigh 10 grams each, & are foam filled I beleive.
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Old 10-16-2006, 10:31 PM   #16
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http://www.runryder.com/helicopter/gallery/17476/ photo of same problem about 5 rows down.
I had that problem first year I had the bird. Had a long thread going on getting it fixed and after a couple of months, Larry B came up with the answer. Turned out that hub was unevenly machined and I had overtightened the bolt down too tight on the bearing making problem much worse.
You can see the dimples in the bearing race.
My bird would lock up and wouldn't let me turn a one direction but I could turn the other.
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Old 10-17-2006, 05:24 AM   #17
Gyan
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Seahawk;
Had you determined if it was the bearing race alone as the issue or the uneven machining of the hub? What I mean to ask was the issues isolated ? Cause both bearing races were dimpled on my tail grips but it would only not turn to the right. Very similar to yours.
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Old 10-19-2006, 05:18 PM   #18
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it was a combination of uneven machining and me being too dumb to realize I was supposed to have a little endplay. If I remember correctly, the Bergens replaced the entire hub and bearings for me.
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