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.

I think anony is onto something 

Great analysis.  Seriosly....  good post

if that’s what happened, that bearing was making some noise and would be felt in the pedals. 

Well here’s an extra piece that is not being reported but I’ll add to this discussion. For 2-3 days prior to the accident n216mh’s tailboom was wagging excessively while on the ground at KJRB. This was mentioned to the pilots multiple times by other pilots, ramp agents and even over the radio by ramp agents running the radio upstairs. They reviewed the security camera footage after the accident and it clearly showed the tailboom wagging far more than any other aircraft. This footage has been provided to the NTSB. 

I initially took that as a potential weakening of the 4 bolt connection that then was allowing an otherwise perfectly balanced and working drivetrain to wag the tail. Other option was an imbalance anywhere on the tail rotor drive train was creating the wag which over time was weakening the 4 bolt connection. Once the wreckage photos showed the fairly clean break at a location that was NOT the 4 bolt connection then I moved on. 

This extra detail is pointing towards a serious bearing/coupling drivetrain issue that had been working itself for quite sometime and finally failed and became a wrecking ball to the top of the tailboom. 

I have seen several long rangers that did this. nobody was too concerned about it so really wasn’t either but I also wasn’t flying it. 

Well I guess that makes it a non-issue then.

say wut

had been damaged at some point in the past (recent or just a few months ago). Someone ran the tail into something or something else was run into it and slightly creased the skin of the tail near the main fuselage attachment point. Might have been able to see it on preflight, might not.  The tail pic showing the separation point is damning.  The rest of the detachments are irrelevant after the tail was gone.

Tail wag on the ground is almost exclusively caused by bad chord wise alignment of the blades.  A lot of mechanics can’t sweep blades correctly.  Not to mention, the system using string and mirrors isn’t exactly foolproof.

Van Horn said having sweep off can lead to their violent bounce that has already ripped a tail off a 206L in flight.

Even with earplugs or sound cancelling headsets, you surely should be able to hear that horrible loud screeching noise several minutes before total catastrophe! 

I want to commend you on your analysis. We don’t get that here too often!

Thank you!

I posted the thread about the theory of the Main Gearbox seizing. After watching the video a few more times, it surely does look like the tail yawed clockwise, which would invalidate my theory of the MRGX failure. 

Great post - Gives us a lot to think about. 

Take a look at the video around the 6 second mark. There appears to be a puff of smoke or maybe something small departing the aircraft. Could be a video artifact too.

 when was the last 300Hr was C/W. T/R D/S Splines get lubes @ 4 places. Was the Thomas coupling bolts not TQ @ Oil cooler or T/R G/B input? Saw that happen (No where near to this extent) to USPP L-3 during Gnd run up after a Baltimore based 145 had just finished a 300hr,. *They no longer were under USPP Contract) The Thomas coupling came loose enough under the oil tank to cut into aft fuselage. Again that was on a Gnd run up had it not happened then it would've in flt.

Agree with the tailboom failure theory but a simpler cause could be loose rivets initiating a crack, which would be hard to detect on a black tailboom. Bell PSE has been drawing attention for years, during maintenance conferences, to these types of cracks, sometimes starting at the driveshaft cover clips. They show pictures of cracks almost 6" long before being detected. When you look at the NTSB photo of the fracture on the remaining tailboom section, you see how it jumped from rivet to rivet at the bulkhead location. Could this be related to the observed tail wag?

The ramp video with the tail wag would be interesting to see.

THANK YOU! Thank you for saying this! 

I have beating my head on the wall lately because I feel like I've been watching totally different videos from everyone else. Everyone has been so focused on the Head that I'm like what videos have you all watched. I clearly see the tailboom crumple or separate first with blades still spinning, then it enters an "auto" (Not a real one, but air flowing up through the rotors with the fuselage leading the way etc...) until eventually those forces rip the transmission deck off, head and all. No blade separation, no mast bumping, none of the other hair brained ideas I've seen around.

Have they found the rest of the tail boom?