My first 700 prob!

[Rctintin]

Was out this evening flying my awesome 700, and after around 7-8 min, I come in for some close up flying having been doing nice big turns and full power climbs, and noticed that something was hanging and flapping around on the tail push/pull control rod. I set her down sharpish, and on inspection, 2 of the 3 guides have snapped off at the end by the ring that fits to the boom. This was the 19th tank through her, and I had only 5 min before that flight put a drip of oil on each slider and the tail controls. There is very little vibration on the Heli, and the tail was balanced when built. There was no foaming in the fuel tank either.

Any ideas what has happened to cause this?

Cheers Rob.

[Aidi]

If 2 of the 3 broke in quick succsesion, then it sounds like it could be vibriation releated. You somehow managed to get vibrating at the exact resonance to which they reacted.

Only a guess, but i wouldn't be too worried about it. Just make sure that you move them slightly when replacing them.

[Rctintin]

It was the first and third one that broke. Also, I put a drip of Cyno on each one around the boom. Should I leave them to 'float'?

[ROSSCO]

Hi,

just a couple of things to check, firstly take the tail gear box off and then spin the rotorhead while inspecting the torque tube inside the boom to see if it runs true, i have come accross this before and sometimes a slightly bent torque tube can cause a resonance problem.

Next, if that is okay:

Check the bearing guides on the torque tube, sometimes one of these can come loose and cause a vibration issue. Also check the location of these, sometimes if they are not in the right location on the torque tube they can cause a resonance.

[Aidi]

With regards to securing them, use a cable tie. Locate the guide on the boom, then slip a cable tie between the boom and the guide. You can either then zip it up and snip off the end or just cut the cable tie either side of the support. You can then still move the tail rod guide forward/backwards if you wish.

Rgds
Aidi

[dav20043]

also make sure they are not evenly spaced as this can cause a resonance issues

[Rctintin]

also make sure they are not evenly spaced as this can cause a resonance issues

The guides or the TT bearings?

[Tim Procter]

The guides or the TT bearings?

Both.

[Rctintin]

I know for certain that the TT bearings are installed as per the instructions, and I did put the guides where I thought they needed to be, not measured.

I have ordered 4 of these from FL tonight:Fast Lad Performance

And another 4 gallons of Optifuel gogo juice

[Downdraft]

Just a suggestion, Maybe the lube you've been using to keep the pushrod running freely has attacked the plastic and caused the problem.
I never lube mine, I simply wipe it down every time i've finnished with it and not had a problems yet (fingers crossed) .

[ROSSCO]

It might be worth checking if you've not already done it, to check that the Torque Tube bearings have not come loose. Sometimes one of the bearings can break free from the CA or Retaining compound which ever has been used and move down the boom causing the torque tube to resonate.

[Kwickkwack]

I was advised when assembling my 700 Not to have the tail guides all perfectly in line, I have them set so the tail drive is in a VERY shallow S (a couple of millimetres offset) so there is a very small amount of side "loading". This prevents them from being able to resonate and has no effect on the movement.

[Janek]

While I don't fly a 700, I've never had to lube my tail, it gets plenty of lube from the exhausted engine oil, which covers everything !