CNC tail failure

[bearwood]

During a hover about 30 secs into my second pack for the day my Sonix CNC tail failed. The hub has sheared clean off and one blade came sailing past me 30' away and the other blade incl holder stuck in the ground beneath the heli. Heli spun 180 degrees and landed on the skids, no further damage. I have cut the grass with this tail whilst landing, hard not to do when the grass is 3" tall. Not real impressed:thumbdown:

This is the tail unit I bought http://www.takeoffandland.com.au/product_info.php?products_id=2584&osCsid=74afe0e3515779af99bfbca7a48c2c63 which is very similar to this unit http://www.helidirect.com/product_info.php?cPath=322&products_id=5869

[helvetic]

During a hover about 30 secs into my second pack for the day my Sonix CNC tail failed. The hub has sheared clean off and one blade came sailing past me 30' away and the other blade incl holder stuck in the ground beneath the heli. Heli spun 180 degrees and landed on the skids, no further damage. I have cut the grass with this tail whilst landing, hard not to do when the grass is 3' tall. Not real impressed:thumbdown:

This is the tail unit I bought http://www.takeoffandland.com.au/product_info.php?products_id=2584&osCsid=74afe0e3515779af99bfbca7a48c2c63 which is very similar to this unit http://www.helidirect.com/product_info.php?cPath=322&products_id=5869

I got the same alu tail rotor. Hmm, I think I'll swap it again!

thx a lot for sharing

[3sgte]

what about tha newt g-force tail assembly for the trex 600? i have the stock 600 tail now and after a crash i need to replace it. i was wondering if the g-force tail would work? it also has those chinese weights built into it.

[3sgte]

i just checked the g-force tail assembly. its just the tail grips and no hub. i guess you will need to use the trex600 tail hub and thrust bearings to make it work.

[Madedon]

I have this unit : http://www.helidirect.com/product_in...oducts_id=5869 (http://www.helidirect.com/product_in...oducts_id=5869)
I was not very pleased to find out that the matterial which holds the two tail grips on the tail shaft was very soft, so soft that I could actually bent it with my bare hand. :bawl

Also these grips have no thrust bearing and above 2200 HS they have the potential to bind.

Anyway I was not pleased with it and replace it with thrusted tail gribs from Trex 600, a bit bigger than stock but worked out very well.

[Happy|Harry]

ouch! i'd only expect to see that happen as crash damage not in-flight! i have one of these tails too so i'm going to replace the hub with a gaui stainless one so as to pre-empt this problem, thanks for the heads up!

[bearwood]

I have sent the broken bits to the HS that I bought it from. They have sent the pics to the manufacturer (Sonix).
I think this hub can be made better by lengthening the threaded hole into the hub and then fitting a longer bolt. I will do a drawing and post it when I get a bit more time.
Otherwise I am going to fit a Raptor rotor.

Nice to see you back Harry!

[Happy|Harry]

thanks bearwood :) let us know what the manufacturer says as this is a serious flaw!

[mjdee14]

Has anyone else had a bad time with this blade assembly?

I hate to use something that will break, but ONE instance dosen't make it a bad part....2, 3 or 4 will....

Anyone running it wih success?

[bearwood]

The hobby shop is replacing the rotor assy but I am not going to refit it. I am going with a Raptor or QuickUK rotor assy.
When the replacement arrives I will strip it down and take some pics with a ruler to show how light this unit is.
The Tail case is really nice, grips onto the boom much better than the Gaui one, nice crank arm. I would recommend one of those.

[crash1000]

Has anyone else had a bad time with this blade assembly?

I hate to use something that will break, but ONE instance dosen't make it a bad part....2, 3 or 4 will....

Anyone running it wih success?


if you can bend it using your hand... will you put it on your heli? I DONT!

[mjdee14]

I went to the helidirect website and although there were no reviews on the 550 tail, there were several on the trex600 tail which is the same thing,,,,and several gave it 4 -5 stars...

I'm going to investigate further, but again....1 problem doesn't mean they are all bad...

I'm not putting mine on yet, and may not, but I would like to have more feedback before we condem the whole lot.

[Happy|Harry]

i've been using mine for a while with no problems, but i'm going to change out the hub just to be on the safe side :)

[bugdozer]

i've been using mine for a while with no problems, but i'm going to change out the hub just to be on the safe side :)

Is there a direct replacement for the hub, using the same grips?

[helvetic]

I went to the helidirect website and although there were no reviews on the 550 tail, there were several on the trex600 tail which is the same thing,,,,and several gave it 4 -5 stars...

I'm going to investigate further, but again....1 problem doesn't mean they are all bad...

I'm not putting mine on yet, and may not, but I would like to have more feedback before we condem the whole lot.

As you can see on the defect tail hub, the broken axis is very thin. I really don't trust the construction of the tail hub. Especially when the thread inside the axis has the same length as the axis itself. This will never get a steady part.
Maybe the thread inside has not always this length, and other tail rotor hubs may not suffer this issue. But once again:
I don't trust the construction, and I replaced the part with the new T-Rex 600 tail rotor.

Maybe I am a scaredy cat, but I don't want to crash because a 26$ part failed.

[Happy|Harry]

Is there a direct replacement for the hub, using the same grips?

i'm not sure yet, but i'll make it work :D. i'll post the details once i have it done ;)

[mjdee14]

Has anyone taken the hubs off of he center ? I tried but it seems like they are pressed on...so it seems it will need the old "heat treatment" like the Gaui mains.

has anyone had a different experience.

[odieser]

I also could not get the bearings out also the bolt holding the blades to the hub could that be any smaller jeese this thing looks great but not sturdy enough for me . Not what i want on my hurry fuselage. going to lead to disaster. I will try the TREX 600 or E620 tail hub and blade holders.

[3sgte]

i have the trex 600 grips/tail hub with the thrust washers and it works great! pretty cheap to. the grips are plastic but very heavy duty. i run around 2300 hs and it holds up great.

[mjdee14]

So far I have been using the gaui tail grips with thrust bearings...they sem to work as good as anything else....

If your not going to go metal...I guess they are OK, unless anyone has had a problem with those.

I sent an email to Helidirect with a link to this thread...we'll see what their answer will be about this situation.

[helvetic]

So far I have been using the gaui tail grips with thrust bearings...they sem to work as good as anything else....

If your not going to go metal...I guess they are OK, unless anyone has had a problem with those.

I sent an email to Helidirect with a link to this thread...we'll see what their answer will be about this situation.

l already opened a new thread about that in the helidirect foum a few days ago.

So far, no answer.

http://www.helifreak.com/showthread.php?t=66951

I found a picture on CNC helicopter from the tail rotor hub. You can see the small axis with the thread inside.

[bearwood]

Helvetic,
You may not get a reply from Helidirect as these rotors are made by Sonix.. I am guessing that Sonix make the parts for the HDX series of helicopters.
Takeoffandland appeared to be quite concerned with the failure and were quite keen to see the failed hub/rotor assy. I hope to hear from them tommorrow otherwise I will ring them to hear there thoughts.

Eddy

Edit: added drawing of hub with a proposed improvement. I believe by extending the depth of the thread further into the hub, the mechanical strength will be increased significantly.

[mjdee14]

Eddy

Edit: added drawing of hub with a proposed improvement. I believe by extending the depth of the thread further into the hub, the mechanical strength will be increased significantly.

The "little" end bolt really got me.....maybe extending all the way to the hub shaft would add more strenth and depicted in the pictures, but the sidewall thickness seems to be lacking also

[bearwood]

After seeing the failed parts in the flesh the Hobby shop will not replace the tail until the manufacturer has sorted out the problem!

So looks like a QuickUK raptor tail for me.

Eddy

[michael88997]

sorry to be off topic but has anybody had any trouble with the plastic gaui grips that have thrust bearings?