Today I was on my third battery on the B 400 when all of a sudden it made a strange loud noise and lost power and tail control. I was able to land it hard with no damage. What happened was that the allen bolt holding one of the tail blade grips on had worked loose and the blade grip with the tail blade flew off. This resulted in an imbalance which bent the tail rotor shaft and locked up the belt causing a loss of power and the quick decent. I searched far and wide for the missing tail blade and grip and never did find them. I imagine that given the RPM's they could get flung pretty far. Of course, this was the only part that my LHS did not have in stock. I had not touched the tail since I bought the heli. Everyone may want to check the locktite on these screws. I am lucking that I landed this baby without damage from about fifty feet up ...it's always something, just when I had this thing trimmed hands off!