Helicopter crash Hudson River

[LittleInch]

Helicopter sight seeing inner York crashed with all dead.

This video looks like it was flying at some speed, then something happens, it seems to change orientation very rapidly which causes the whole tail structure to detach, followed shortly by the main rotor blade and part of the gearbox. Horrible way to go.

https://www.reddit.com/r/CatastrophicFailure/comments/1jwfxh9/full_video_of_the_helicopter_crash_in_hudson

Six people killed after helicopter crashes into Hudson River in New York

Pilot and a family with three children who are believed to have been Spanish tourists were killed onboard aircraft

www.theguardian.com

 

[goldgelb]

What a tragedy.

I'm not very knowledgeable about helicopters, but It seems the Bell 206 has had some reliability issues with the freewheel unit (specifically due to lubrication issues, see the links below). To my understanding, if the freewheel unit seizes during a gearbox failure, the forces could be great enough to shear off the rotor. Unsure if this would be enough to also separate the tail from the fuselage as in the video. Another failure mode is described in the second link, where the freewheel unit suddenly engaged with engine RPMs significantly exceeding rotor RPMs, shearing the rotor mast.

Perhaps someone more knowledgeable could shed some light on whether these scenarios are applicable to the situation in question.

1. https://www.casa.gov.au/sites/defau...lures-mast-yielding-main-rotor-separation.pdf
2. https://www.pprune.org/archive/index.php/t-561337.html

 

[LittleInch]

I don't think it is. Those are related to the snapping or breaking of the main rotor shaft. It seems the main rotor came off way after the initial incident with the tail rotor or tail assembly.

It seems that the helicopter was horsing along at about 100 knots and something seems to have happened which has thrown the chopper sideways violently and caused the tail to either hit the main rotor blades or simply snap off. Then its in a death spiral and the main rotors come off about half way down.

What that something is is not clear and could be either a snap change of the tail rotor from one angle to the other or a gearbox failure or tail rotor seizure.

 

[Rabbit12]

The images of the family photos just prior to this incident are heartbreaking. They are excited about a sightseeing trip not knowing their lives are going to end in a few short minutes.

Always good to remember you aren't guaranteed tomorrow.

 

[LittleInch]

is a zoomed in version https://streamable.com/56ttmc

Looks like something very dramatic happened which caused the helicopter to yaw and spin violently to the right which caused the break up of the tail.

The money seeks to be on main gearbox failure and hence may have weakened the gearbox which then broke off along with the main rotors.

So possibly if the main gearbox jammed and the motor flung the helicopter round before it probably broke something. Once the tail went there was no getting it back.

 

[Sym P. le]

It appears the aircraft experienced directional stability issues which caused the tail assembly to separate and subsequently the rotor assembly. Note the original video is not continuous.

 

[TugboatEng]

Got 20 minutes? Here is a video on mast bumping.

Some helicopter can strike the tail boom with the rotor under some conditions. Robinson is notorious for this.

 

[Sym P. le]

The tail assembly appears to become unstable as the aircraft starts yawing (or what appears to be yawing). Given the unknown compression parameters applied to the original video, it's difficult to assess what may be algorithm induced artifacts.

Edit: The aircraft might have already rolled 90deg as it enters the view of the camera.

 

[Alistair_Heaton]

Honestly if you don't need to go in a helicopter. Don't go in one out of choice.

They are great when you need them but the additional risk is way above most other forms of transport.

The pilot it seems was ex military and was reported by his peers as more than competent. Not that really precludes a human factor mistake.

 

[XR250]

So possibly if the main gearbox jammed and the motor flung the helicopter round before it probably broke something. Once the tail went there was no getting it back.

My money is on that.