Originally Posted by
rotorfossil
If there is an unexpected power loss, the first reaction is "what's happening"? Followed by either far too slow lowering of the lever or no reaction at all. Result- massive drop in rpm, rotor blow back and break up.
Among the tail chop incidents are surely some following this pattern. But from quite a number of descriptions it is very clear that there are other cases where droop of RRPM did not occur. Neither typical low G maneuvering with subsequent violent Right roll.
These 'unexplicable' ones are the real worrying ones since it is not clear how to avoid them. Due to rareity of events and the sudden progression once they occur I also slightly tend to assume something structural or combined aero- elastic + structural. Most of the totally inexplicable ones appear to have occured above 80kts. This also seems to point in the direction aerodynamic/aero-elastic.