It happened again!

[Pablochopper]

I was letting a buddy at the field fly my newly rebuilt nx4 today and it happened again. Blade grip snapped off at the hub. I just replaced all the bearings so I know it's not that. This is twice now. Any ideas?

[Pablochopper]

No one else has had this problem?

[LoveToFly1]

Originally Posted by Pablochopper

I was letting a buddy at the field fly my newly rebuilt nx4 today and it happened again. Blade grip snapped off at the hub. I just replaced all the bearings so I know it's not that. This is twice now. Any ideas?

i have not seen this particular issues before....that really sucks. shoot gaui an email about this, so if there is a bad batch, they can make an announcement.

[u8at711]

Any time the tail touches the ground or 100 flights, I replace my tail hub, it's what a 3$ part,
I always have one or two in my field bag.

I even change the gears when they show signs of wear or have been stressed, from the tail striking the ground,
To me it's routine maintenance.

Don't over tighten the nut, don't use old worn nuts.

Inspect all linkages, bolts, nuts, Ect, every flight.

[Pablochopper]

Thanks, I'm gonna rebuild it one more time keeping that in mind. I don't auto with this heli other than on landing from about 2 feet. Might have bumped it then I guess.

[mmracecars]

not sure on that one,ive plowed mine in a half dozen times,still on the same tail hub.

[Laurens]

Its already mentioned, but overtightening this bolt really puts a huge stress on it. Just snug will do, loctite keeps it in place.

[LoveToFly1]

i have replaced my tail hub after every crash. i bought this heli used, and had an odd tail bounce on stops, so i replaced the entire tail assembly when i couldnt tune the bounce out of the FBL. my question - if i tighten the lock nut down, it binds my bearings. i have gone over the installation diagram 100 times, and all the shims and proper bearings are in there (i replaced the tail grips when i first got it and they come with the bearings and shims in it already). is this normal? i have to just tighten the lock nut down until it is snug, but not tight to the bottom of the hub. i would have figured that it would be designed so that you could not bind the bearings by tightening it too much....

[u8at711]

Originally Posted by LoveToFly1

- if i tighten the lock nut down, it binds my bearings.

that happens with mine also. Keep mine tight enough so there is no play, and not binding.

sometimes the way the weather is, motor tuning, and how healthy the tail linkage & tail servo is will play games with the tails response.
I've replace worn linkage balls, worn bell crank, bearings, slider bushing. ect.
still running the stock CF Gaui tail blades.

if you have a cracked main frame or servo grommets that let the servo move too much,
even loose boom supports can cause weird tail behaviors. adding one more tail rod guide helps also.

[LoveToFly1]

yes, i checked the usual's, i began diagnosing the smaller issues. like out of whack thrust bearings, worn radial bearings, dry thrust bearings, slightly bent hub (smaller than the eye can see), things like this.

is just odd. i like the idea of the lock nut, you would have thought they would have designed the thing so you can crank the nut down all the way to the shoulder and it not bind, like tails are designed on other helis, you can crank the bolt down and that is all you need.

[KSHeli]

An acquaintance of mine sold his NX4 this summer after this happened for about the 4th or 5th time, I would make sure your gov gain isn't high. I don't know if this is the problem but after hearing the tails on my electrics hammering from too high a gov gain, it may be at a level that you don't even hear it, just a thought. The rapid gov changes could be crytallizing the aluminum in the tail hub.
Just a possibility, I really don't know anything this is just my thoughts on a possible cause, so take it for what its worth.

[S.Millar]

I have three Gaui heli's using the same style tail hub. I have never had an issue with one breaking.

If I hit the tail hard in a crash I usually replace them. I also just tighten the nut enough to remove any up and down play. Don't snug the nut too much.

I have seen a few posts in this NX4 forum claiming these hubs are faulty. Some guys even replacing them with Raptor parts. If they can handle 82mm tails on a 12cell X5 I think they can handle a tiny nitro. It all comes down to the way you put it together IMO.

[Pablochopper]

I've got an x4II with no vibs. (Vbar logs are great) just to be clear, I don't think its a faulty tail. I agree that it must be something I'm doing or not doing. But my electrics don't have this problem. I am sure it's a high resonance vibe. Probably made worse by the fact its a nitro.

My plan for solving this is to bite the bullet and buy a full size vbar so I have the spectrum analyzer and take off the ikon. Then switch the Cnc tail grips for plastic x5 grips. For now it sits on my shelf till I can afford the full size vbar.

[Pablochopper]

Originally Posted by S.Millar

I have three Gaui heli's using the same style tail hub. I have never had an issue with one breaking.

If I hit the tail hard in a crash I usually replace them. I also just tighten the nut enough to remove any up and down play. Don't snug the nut too much.

I have seen a few posts in this NX4 forum claiming these hubs are faulty. Some guys even replacing them with Raptor parts. If they can handle 82mm tails on a 12cell X5 I think they can handle a tiny nitro. It all comes down to the way you put it together IMO.

If you don't have this problem then why post? did you know that high rpms can cause more vibs? So smaller birds are going to be more susceptible to failurs caused by this than bigger birds. Are your three gaui's nx4's? coming to a post where a guy is asking for help and saying that it's not the birds fault helps very little. Its great your stuff works well.

Thanks though

[S.Millar]

I have 2 NX4's, 1 X4ii, and an X5.

[Pablochopper]

Originally Posted by S.Millar

I have 2 NX4's, 1 X4ii, and an X5.

Well, now it's 4 Gaui's. My mistake, that's more than enough to jump on a thread and say that anyone having this issue is just built it wrong.