Originally Posted by Hairyplane
Thanks for that.
Obviously these things dont always get reported do they?!
Correct
Are checks for overspeed routinely done? At what intervals? Is the tail rotor shaft checked for runout at intervals?
That's up to the owner/operator, otherwise only at the 600-hour and/or Annual.
Has there ever been an R44 failure attributable to overspeed?
Not that I've read, but it could have happened.
In a rotor overspeed, one area of the Robinson rotorhead that takes damage is the spindles and bearings in the pitch housings - the centrifugal force causes the bearings to make "dents" in the spindle races, causing mistracking and vibration. It can also cause the aforementioned T/R driveshaft damage. If RRPM exceeds a certain percent, the main rotor blades must be replaced. If the engine is also involved, an overspeed might mean a mandatory engine rebuild (depending on how high the RPM went).
All this horror story stuff being said, generally the only way (outside of malfunction or blatent abuse) to get an overspeed is when practicing autorotations or performing rapid decelerations. Engine overspeeds are also possible on startup, but on the whole seem fairly rare, with overspeed-related engine failures rarer still.
To be honest, I'd be more worried about folks exceeding MP limits in cruise or exceeding max gross - both are easy to do, especially in the Raven II, which has plenty of power to allow both. Obviously, as soon as your helicopter is out of your sight, you can't know what is happening to it, but as long as the folks flying it can be trusted not to practice autorotations and quick-stops, and are well-trained in general, the aircraft should be fine.