Originally Posted by
Robbo Jock
Wonder if the TR flex coupling let go, that could have created an effective little circular saw inside the tailboom which would explain the fairly neat cut.
I agree that failure of the aft flex coupling could cause all sorts of havoc, but tail rotor blade failure is still my guess. Take a look at this photo from the ATSB Preliminary Report.
Well, I've not had much luck in posting photos in this forum, and I apologize for my inability to post photos. Just take a look at the report; however, the next paragraph should provide enough information, since it describes a related feature of the photograph.
A "Tail rotor blade section" was found approximately 100 meters south of the "tail rotor and gearbox" remains, which indicates an in flight break up to me. That plus the AD on tail rotor blade cracking indicate a possible in flight tail rotor blade failure. Such a failure would also account for the separation of the tail rotor and gearbox and the fragmenting of the aft bulkhead of the tailboom.
Just a thought, but it may be interesting to ask the pilot, who flew the helicopter and discovered the pedal "vibration" on his flight of 29 June, 2020, whether or not the vibration changed with right or left pedal movement.
Just my opinion.
Regards,
Grog