Originally Posted by
GrayHorizonsHeli
thats why I asked, I figured that as well, if the washer was suspect for any reason it would be part of the AD.
Incidentally for simple random information totally unrelated to this case, I was disassembling some AS350 control rods today, and while cutting the lockwire, the nut started turning. the lockwasher design didn't stop the nut as it was just a place for the lockwire to terminate.
The "double locking" in this case did its job although the proper torque was not on the nut.
However, nothing further would have happened because the lockwire, torgue and locktabs, on the other end would have all had to fail too before bad things happened.
This is a dangerous assumption, in part led by a pervasive culture that safety wire, cotter pins, etc. actually help keep a joint together. Proper torque keeps it together, and absence of torque can lead to high loads from vibration even on parts that are not thought of as load carrying, wear on threads can be just as bad and can lead to loss of control. That rod should be replaced, or possibly NDI inspected for damage, but at minimum raise awareness... do not ignore "loose nuts found on good parts".
earlier posters describe uncommanded full actuation which would certainly be possible probably likely, with failures on the subject side of servo. A neutral tail rotor would not cause aircraft to keep spinning after main rotor torque was dropped, it would slow down, and if biased it would actually turn the aircraft to the left. Yes, a missing nut could do this, but for all we know, they found a fractured end of servo. One cause of that could be... incorrect or inadequate torque on the nut. An initial inspection is prudent.