Please watch this video  

I ask that everyone watch this link to the original footage that shows the entire accident sequence.

https://www.youtube.com/watch?v=graz-V-Hksw

Turn sound on!

We have all seen this one at this point but depending on where you watched it, the media scrubbed the audio off of and talked over it.  Slow it down, you will clearly hear the sound of a tail rotor drive shaft impacting the metal of the tailboom.  Those of us that have had this done in the simulator will immediately pick up on the similar sound. This sound precedes all visual cues.  Use the visual impact of the fuseluge hitting the water and the appx 1.5 seconds of delay before the sound reaches the cameras microphone.  Now go back to the beginning of the video and when you hear the first thump, go back 1.5 seconds and keep replaying that.  It will be become clear that the sound precedes the yaw to the right. What you hear happens 1.5 seconds before you hear it. You can hear the rpm of the sound stays fairly steady and stopping after 2 seconds.  What lines up with 2 seconds after the visual of the incident beginning? The main rotor impacting the free floating tailboom.

With the wreckage photos we have now, the tailboom to fuselage joint is intact but it is broken at the next segmented ring frame.  That at least removes the theory of the 4 bolts or any of the frame being an issue.  That same video above if slowed down and zoomed in there is a frame or two that shows the tailboom completely separated from the aircraft and intact fly up and into the main rotor where it gets cut in two pieces that we can track till water impact.  

The wreckage photos also show the top of the fuselage is torn apart and paint removed directly below the driveshaft behind the hangar bearing bracket, the bearing is completely gone.  

A tail rotor driveshaft failure starts the right yaw as the tail rotor begins to slow immediately.  At the same time, the engine side of the break in the driveshaft is now flailing around and hammering the top of the tailboom, a coupling or bearing failure allows this much movement to occur.  This weakening of the tailboom happens instantly and the aircraft yaws to the right putting the tailboom way out into the 85-90kts of wind and puts so much load on it that it fails.  This allows the yaw to continue past where most of us would expect the weathervaning to have stopped it.  The tailboom folded as it went out into that airsteam because of its weaken state.  You can actually see that happen when you watch the fuselage begin its first few degrees of yaw but the tailboom does not follow it.  

The tailboom now completely free of the fuselage, which happened as the body of the aircraft gets between the camera and the boom turned almost vertical and was only then cut by the main rotor and we clearly see that in the video.  That forced being applied to the rotor system created such a reactionary torque and imbalance in the system that main rotor system torn itself from the airframe but it took an additional 2.5 seconds of force being applied before the transmission and rotor system pulled inself along with the airframe off the rest of the fuselage.  The main rotor continuing to spin at a very high rpm all the way to the water.  There is absolutely no seizing of the MRGB that would have the rotor system come to complete stop and then restart again after tearing itself out of the aircraft especially when we can see in the video that the rotor system never stopped spinning till it impacted the water.