700 New to me Trex 700L Dominator

[jcfernan51]

This is certainly not normal for a trex 700, those gears are normally pretty tough.
There is obviously a real physical problem somewhere in the system. If you are sure that the bevel gears were properly assembled and meshing correctly then it's really got to be something jamming the tail rotor or the TT and stopping it turning, or making it very stiff to turn. Have you removed the tail rotor assembly and checked that is spins freely while moving the the pitch slider into all positions along the shaft, also that the shaft isn't bent? Check that the inner bush on the slider is also free to turn within the slider body.. The bearings on the TT and the umbrella gears would be the other things to check. I can't see how it could possibly be the TT itself, it's just a shaft, as long as it's straight then it's ok.

Smooggie, This is the third time this happens. I am with you there has to be some mechanical issue in the tail. Something is making the umbrella gears either stop or disengage causing them to strip and it has to be in the tail assembly because the drive gears have always looked good. This time I removed the TT and it looks as-straight-as it can be. One thing I am thinking of doing is adding a third bearing in the middle in case the TT is flexing some causing the gears to not properly mesh or the bearing to bind. The last time this happened, prior to my video above, I replaced all the gears and I made sure the TT was spinning free and that there was no play in any of the gears. My suspicion has always been that at speed something is stopping the TT from spinning is the only thing that can explain the stripping of the front umbrella gears, maybe the TT bearing? I did not rotate the TT and check the pitch slider was smooth while spinning, it was a new gear/shaft, the one I removed was not straight and I though I found the problem, I guess I did not.
It is interesting and confusing how many of the gears and specially bearing are used across the 500/600/700 models. I am looking for parts and the package is labeled 600 or 500 but the part number is the one for the 700 according to Align's site.
Once I get all the parts I will post an update. At least I was able to take it off the ground once in the 4 month I own it.

 

[Smoggie]

There is something odd about the part number because the 600 uses a different (smaller) umbrella gear to the 700, and the 500 is smaller again. What part numbers do you have?

Definitely worth checking all the points i mentioned in the last post regarding the tail slider position and the rotation of the bush inside the slider.

 

[jcfernan51]

Well that is interesting if the gears are different I would expect the baring to be different unless the gear outer shaft is the same to fit the same bearings. Here is the link I am using to find part numbers. EDIT: this link looks bad but it works

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Reading my last post again the way I wrote it is confusing, the umbrella gears are for 700 but the bearings are used across multiple platforms. For example HN6032 or HN60125 Bearing when I am searching and open a site showing the bearings and I see a package labeled 600 it makes me question it and if you saying the gears are smaller in the 600 than the 700 I assume the shaft to be smaller but maybe that is not the case. Even the Align store site when I search for the number it shows the 600, Bearing (6701ZZ) H60125 .

 

[jcfernan51]

Update; I replaced all gears again but this time I replaced the bearings as well. I took it to the field and had a successful flight on Saturday. I will be going to the field again today and will take video because I know you all like them.

Juan

 

[Smoggie]

That's great news, so it sounds like the bearings were faulty and jamming under load?

You are right, the TT and tail boom are the same diameter on the 600 and 700, and the bearings are the same too. I use the 700 boom and TT on my slightly stretched 600 pro. The gears themselves are different though.

 

[D.O.G.]

Update; I replaced all gears again but this time I replaced the bearings as well. I took it to the field and had a successful flight on Saturday. I will be going to the field again today and will take video because I know you all like them.

Juan

Hey there Juan. Glad to here that you got your bird up and flying. Yes, some video would be nice to see that Condor in action .

 

[jcfernan51]

Here is the video

[video=youtube_share;2-dmtASLSoU]https://youtu.be/2-dmtASLSoU[/video]

 

[D.O.G.]

Nice one Juan. You have one sweet sounding, flying gentle giant their. Good luck on your many flights to come.

 

[jcfernan51]

Thanks D.O.G., now need to learn how to fly it and that only happens by flying.

 

[jcfernan51]

After many successful flying the inevitable happened Tuesday. Was hovering close to the ground over grass nose in, went to back up and the tail hit the ground. Need to replace main and tail blades, main drive gear, boom, and bolt that hold the main rotor grip arms. In the mean time flying the airplane,

 

[D.O.G.]

Sorry to here that the ground got in the way of the tail blade. Hope that it's a cheap fix. At least you have back up, The plane!

 

[jcfernan51]

You know the bigger the heli the dipper the pockets, the main blades alone are over $100

 

[Tony]

That sucks to hear. Hope you get it repaired quickly.

 

[trainrider06]

You know the bigger the heli the dipper the pockets, the main blades alone are over $100

yup advance from 450 to 500 prices go up, 500 to 600 and beyond, the sky is the limit....