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T-REX 500 › Crashed my trex 500 esp
10-20-2009 03:49 PM  8 years agoPost 1
Romak

rrApprentice

Scotland

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Crashed my trex 500 esp last week!

Yep, crashed when landing. Wasn't descending fast but suddenly the ground rose up to meet me. Careless piloting!!!

Not a lot of damage, Main blades, flybar, set of gears for a DS 510 servo and a lot of hurt pride. Anyhow, it is all rebuilt now and flying.

That brings me to the point of this post. When test flying after the rebuild, I could hear a noise from the bearings, sounded like a small bird in the canopy going tweet tweet. The noise wasn't always there. If I took the heli up to about 30 feet, then quickly took of the pitch of the blades I could hear the tweet tweet. As soon as the load was back on the noise would disappear!

I changed the motor for a spare...no! not that. I changed the main bearings...no, not that. I changed the one-way bearing...no! not that. I even removed the tail boom complete and still the noise was there.

I took out the main bearings again and they seemed to be ok, very smooth to turn, not "notchy". I examined the main shaft more closely this time and there was slight discolouration of the shaft where the bottom bearing sits. I tried a new shaft in the bearing and they felt slack...maybe!

I reassembled the heli this time I put a tiny amount of locktite on the shaft for the bearing taking care not to let the stuff enter the bearing.

After the locktite had dried, I went out for a test hover and hey presto!! problem solved, no more budgie in the canopy.

Question is, what do you guys do in this situation? Do you as a matter of course locktite these bearings in place? Do you locktite any bearing that is fitted to a metal shaft or bearing housing?

If you don't use locktite what do you recommend?

I happen to have a micrometer and I measured my main shaft at 7.97mm diameter. Main shaft bearing inside diameter is 8.00mm. Any comments?

Cheers

Rod
14sg....... ;-)

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10-20-2009 04:26 PM  8 years agoPost 2
colsy

rrElite Veteran

Cambridge, UK

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I have always used 'bearing retainer' on the main shaft.
Some of the tolerances have been hit and miss, especially align's.

col.

Only Quote From Experience.

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T-REX 500 › Crashed my trex 500 esp
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