The best way to prevent any mechanical failure is to simply go over your helicopter before every flight. I can personally attest to the fact of this saving my butt multiple times. I usually check every ball link and every high stress area bolt to ensure nothing is coming loose or has play.
You can't catch everything all the time of course. I've had my tail rotor fail in flight causing a crash, even after a full pre-flight inspection. Sometimes, stuff just gives. All you can do is excersize due diligence and hope for the best anytime you fly.

I do agree with you though helijack. People who fly too close can potentially cause problems for the rest of us in the event something DOES go wrong. But there really isn't much you can do about it.

If theres a few guys in your club who fly too close, you can try talking to them, but in the end, it comes down to each pilot every time they spool up that rotorhead. You can only hope nothing goes wrong.