Flying on the weekend with my Trex 600Pro DFC and during a fast ascent the front bevel gears driving the torque tube to the tail rotor stripped completely and I lost all tail drive. Probably more by dumb luck than skill I hit throttle kill, which stopped the wild pirouetting, and again probably more by luck I managed to auto-rotate it down for a safe landing. No harm done other than the bevel gears and my underwear
The bevel gears were around ten flights old, they were the new upgraded and supposedly stronger black ones. I've not had any tail rotor strikes in the ten or so flights since fitting the new black gears and there wasn't much slop in the gears. I never had any issues with the old type white ones, I'm thinking of just putting those back
Here's what the gears look like:
Apparently having the governor gain too high may be part of the cause of this. I had the gain on the Castle ESC set to 'medium' which is a value of 25. The advice I've been given is to set it below 15. I've also added some shims to the hears to remove the slight play that was there, which is supposed to help. Hopefully that will avoid the same thing happening again. I'm beginning to understand why many people prefer belt drives!