NY Bell 206 crash

[A64Pilot]

I’ll start the speculation based on no facts.

I think either Swashplste failure or Pitch Change links failure, either would sever main rotor control which would lead to mast bumping and that means everybody dies.

 

[PT20J]

Wouldn’t a mast bump cause separation near the hub? This still from AvWeb kind of looks like maybe the whole transmission and main rotor separated together.

[N201MKTurbo]

So, the tail boom came off. Doesn’t that happen when you get the rotor too slow? Or, try to arrest a descent too fast? 
 

There was a report that he may have been low on fuel. If the engine quit and he was slow to get with the autorotation program, could that have caused a tail boom strike?

[PeteMc]

There was an "expert" on that said that with those kind of helicopters, an improper auto rotation procedure could cause the blades to hit the boom.  I would then think the blades would all shatter off as we saw in the video of them missing from the helicopter and appearing to fall in pieces.  

I know very little about helicopters.  But I'm unsure about the "experts" comment because I wouldn't think there would be any initiation of auto rotation until much lower when you use what little inertia you have from the blades to use up to slow you're contact with the ground/water.  I would think it would just be full collective in the appropriate direction to build up the speed/inertia you're going to use when you get down very low. 

Any "rotor heads" here that can educate us?

 

 

Edited April 11 by PeteMc

[N201MKTurbo]

So, did the tail boom strike cause the rotor to come off, or did the rotor coming off take the tail boom out?

[N201MKTurbo]

3 minutes ago, PeteMc said:

There was an "expert" on that said that with those kind of helicopters, an improper auto rotation could cause the blades to hit the boom.  I would then think the blades would all shatter off as we saw in the video of them missing from the helicopter and appearing to fall in pieces.  

I know very little about helicopters.  But I'm unsure about the "experts" comment because I wouldn't think there would be any initiation of auto rotation until much lower when you use what little inertia you have from the wings to use up to slow you're contact with the ground/water.  I would think it would just be full collective in the appropriate direction to build up the speed/inertia you're going to use when you get down very low. 

 

My little helicopter experience suggests that you need to start the autorotation immediately to get the rotor RPM up or else bad things happen.

[PeteMc]

23 minutes ago, N201MKTurbo said:

My little helicopter experience suggests that you need to start the autorotation immediately

I understand getting the speed up.  But  which way do the blades flex when you start that process. 

I was thinking there was more of a flex when you go to slow and the mass of the helicopter pulls down away from the blades when you go to slow down, then (my term) bounces back up and can some times cause the blades to flex.  But that's just my guess based on how inertia and mass can react with a moving body and flexible pieces. 

 

[201Steve]

All of this online discussion about helicopters self destructing ~for wild~ maneuvers like "pitch change" and simply trying to save the craft from an engine failure.... sure makes me all the more suspicious of helicopters AKA whirly death birds.

[Yetti]

I am going to say based on the size of what still is attached to the rotors, the whole Engine came loose from the airframe.   

[EricJ]

3 hours ago, PT20J said:

Wouldn’t a mast bump cause separation near the hub? This still from AvWeb kind of looks like maybe the whole transmission and main rotor separated together.

 

2 hours ago, N201MKTurbo said:

So, did the tail boom strike cause the rotor to come off, or did the rotor coming off take the tail boom out?

 

An acquaintance I used to race with bought a UH-1H out of a museum and flew it around for a while.   He was not a very responsible-type of person and flew it in what was evidently a bad configuration in ways it should not have been flown, and he was told as much by more than one person.    Repeated mast bumping ultimately caused rotor separation and when the rotor came of it sliced the crap out of the airframe, including chopping the tail off as well as neatly slicing off the entire right side of the helicopter which separated with the main door still in its tracks.   

If you want to go down a rabbit hole of learning how not to do things with a Huey, you can follow the links through the NTSB report to the supporting documents, etc.

https://asn.flightsafety.org/wikibase/wiki.php?id=160816

 

[A64Pilot]

A few things, the transmission on a 206 is held in by two inverted V braces, one on each side, then there is an elastormeric “box” right behind the transmission that dampens movement, connected to this link is a round pin that sits in a square hole, excessive movement cause the pin to hit the hole and is called “spike knock”, we dreaded spike knock, usually got it in a touchdown auto by not leveling the aircraft on touchdown, at Ft Rucker if you got spike knock you got to wear a RailRoad spike hung around you neck for all to see. It wasn’t common I never saw anyone wearing the spike.

The engine isn’t connected to the transmission except by a driveshaft and it’s pretty much like a auto driveshaft, no structure to really hold the two together

The instant the engine quits, you immediately lower the collective to maintain rotor RPM, then at the bottom of the Auto you first decel which adds energy into the rotors, then finally use collective to cushion the landing. Having said all that the Bell products generally have more mass in the rotor system than others meaning they are much more forgiving in an autorotation, it’s possible the pilot could have been completely stupid and not put the collective down, but unlikely if they were decently trained being a Commercial pilot surely they were.

Two bladed rotor systems are semi-rigid underslung, meaning simply that neg G or low rotor can destabilize the rotor and it tester back and forth and “mast bump”, mast bumping may or may not tear the mast off, I believe newer Civilian Bell’s have big springs in the Hub to help prevent mast bumping, mostly during shut downs etc from wing gusts, and I think that could have help prevent the mast from being broken off, but if a swashplate fails, it sealed and the PC links break and the rotor will come off, maybe breaking the mast or maybe just tearing the transmission out. Yes the blades most certainly took the tail boom off, if they were at full RPM they had plenty of energy to do that likely without breaking.

UH-1 Transmission is completely different, to begin with it’s about 8 feet tall, held into the Huey with four “candle sticks” and a Lift Link at the bottom, you can’t get “spike Knock” in a Huey and as such you don’t have to level the aircraft before a touchdown Auto, the 206 tranny sits on top of the cabin top where the Huey one goes almost to the bottom of the aircraft.

I was a 67V, an OH-58 Crew Chief for five years and flew them in flight school, an OH-58 is essentially a 206

Edited April 11 by A64Pilot

[GeeBee]

Lot of "Jesus Nuts" on a rotorcraft. You know the ones where you pray to Jesus that nut does not let go.

 

[N201MKTurbo]

55 minutes ago, GeeBee said:

Lot of "Jesus Nuts" on a rotorcraft. You know the ones where you pray to Jesus that nut does not let go.

 

That’s assuming it was a mechanical failure. I hope so, it looks like the pilot was a stand up guy.

[M20F]

13 hours ago, GeeBee said:

Lot of "Jesus Nuts" on a rotorcraft. You know the ones where you pray to Jesus that nut does not let go.

 

That’s why helicopter pilots got dez nuts. 

[A64Pilot]

17 hours ago, GeeBee said:

Lot of "Jesus Nuts" on a rotorcraft. You know the ones where you pray to Jesus that nut does not let go.

 

One actually, it holds the rotor head on. I’ve never head of one failing, but if it did, it would be bad.

There we’re a few Swashplate failures on the AH-1 Cobra, came from the Army installing Kaman 747 semi symmetrical rotor blades to increase useful load, problem is the center of pressure moves aft with increase in angle of attack on a semi symmetrical rotor blade, this back fed pressure into the swashplate that it wasn’t designed to handle. The rotating portion of the swashplate would stop rotating, the Pitch Change links would break, most likely blowback would have the rotor pitch up heavily, the tail boom is cut off and of course everybody dies.

Except for the fact that the mast isn’t broken off, this NY 206 crash looks very much like the AH-1 failures, difference is I think that your not ripping out the main transmission of a Cobra, but there isn’t much holding in one on a 206, perhaps one of the inverted V braces that hold the tranny in broke? Or unlikely I think but the transmission seized?

[Hank]

On 4/11/2025 at 7:13 PM, GeeBee said:

Lot of "Jesus Nuts" on a rotorcraft. You know the ones where you pray to Jesus that nut does not let go.

 

I always heard it was the big nut on top of the rotors, as it was the only thing between you and Jesus.

6 hours ago, A64Pilot said:

One actually, it holds the rotor head on. I’ve never head of one failing, but if it did, it would be bad.

That nut on the tail rotor fell off of a helicopter my dad was flying, circling to pick up an admiral. With no tail rotor, he did an autorotation into the SC sea oats. Grounded all USN Sikorskis at the time (c. 1960), turned out the nuts were out of tolerance from the factory. 

Ya'll be careful out there!

helicopter--(noun) a flying machine composed of many moving parts, all rotating around an oil leak.

[PT20J]

Preflighted a Schweitzer 300 just out of annual inspection and found bolts on all three pitch links missing cotter pins. Told the DOM he couldn't be my friend again until he replaced them. Always preflight these things carefully.

[A64Pilot]

I would like to have a Hughes 269/300. It’s what I learned on in flight school, we called them LOB’s for little orange bastards. Slow as a Cub and about as powerful, but they were very responsive and fun.

All Hughes helicopters are pilots aircraft, the 206 is not, it was made for the guy in the backseat.

[N201MKTurbo]

1 hour ago, A64Pilot said:

I would like to have a Hughes 269/300. It’s what I learned on in flight school, we called them LOB’s for little orange bastards. Slow as a Cub and about as powerful, but they were very responsive and fun.

All Hughes helicopters are pilots aircraft, the 206 is not, it was made for the guy in the backseat.

The 300 is the only helicopter I have flown. I have about 2.5 hours in it. I can fly it good enough that if the flight instructor passes out I will get him to the hospital in one piece, but I’m not landing at that little heliport. I’m landing in a big empty parking lot.

[A64Pilot]

Hovering is the trick, if you can hover you have it licked, flying it’s just like an airplane without the inherent stability is all

[N201MKTurbo]

16 minutes ago, A64Pilot said:

Hovering is the trick, if you can hover you have it licked, flying it’s just like an airplane without the inherent stability is all

Height above the ground was a piece of cake. If I looked forward I could keep it from going left to right. If I looked sideways I could keep it from going fore and aft. I never got them both going at the same time. Another hour or two and I would have it nailed.

[A64Pilot]

Just saw a video of the main XMSN and rotor assy. They were attached to a big chunk of the cabin roof, the 206L XMSN and it’s mounts are a little different than it’s little brothers but very similar, Seems the mount didn’t fail, the cabin roof did. So did the cabin roof failure cause the accident or was it a result of the accident?

The cabin roof on the smaller 206 is a honeycomb assembly of aluminum and was very prone to voids, we had to shoot filler in the voids on Military OH-58’s, the voids significantly reduce the strength of the honeycomb, I assume the bigger L model is the same.

 

Edited April 15 by A64Pilot

[Old Chub]

The 206L series uses what is called a nodal beam suspension system that allows the transmission vertical movement in relation to the cabin unlike the OH-58 and 206A/B series.   In flight breakups are uncommon in relation to how many flight hours the entire 206 fleet has flown and for the entire roof structure to separate from the cabin in-flight is extremely rare.  Investigators will look at the cabin and the tail boom attach points (or where it separated from the cabin) to determine if one failed from fatigue or overload.  

[Matthew P]

On 4/11/2025 at 2:12 PM, PeteMc said:

There was an "expert" on that said that with those kind of helicopters, an improper auto rotation procedure could cause the blades to hit the boom.  I would then think the blades would all shatter off as we saw in the video of them missing from the helicopter and appearing to fall in pieces.  

I know very little about helicopters.  But I'm unsure about the "experts" comment because I wouldn't think there would be any initiation of auto rotation until much lower when you use what little inertia you have from the blades to use up to slow you're contact with the ground/water.  I would think it would just be full collective in the appropriate direction to build up the speed/inertia you're going to use when you get down very low. 

Any "rotor heads" here that can educate us?

 

 

He was NO expert.

 

[Matthew P]

Former Helicopter guy for 20 years so for what it's worth... here's what I'm speculating, won't know until NTSB report but there have been so many "EXPERTS" that know absolutely NOTHING about what they are talking about... Was NOT the Jesus Nut, if it were the rotor head would have separated from the mast and would NOT have fallen intact with the transmission..., was NOT mast Bumping as they were not in a negative-g and operating at full engine RPM......There is another video out there that shows the helicopter flying straight and level 5 seconds before it started breaking up...the initial event started at the tail boom where the vertical stabilizer and tail rotor gearbox is mounted, if you look closely, you can see it buckled and broke away from the aircraft, the loss of the weight of the tail rotor gearbox at that arm caused the nose of the helicopter to pitch down due to sudden forward shift of CG, the aircraft also started rotating to the right as it was at full operating power and no longer had any tail rotor authority to counteract the torque of the main rotor system..the pilot's initial reaction ( as would mine), to the rapid pitching down of the nose, would be to pull back on the cyclic, which you can see thereby resulting in the rotor system making contact with the tailboom and cutting it off forward of the horizontal stabilizer...the violent impact and vibration of the rotor system, as the blades broke apart and became unbalanced, resulted in the transmission breaking away from the aircraft which is why you see the transmission and rotor head falling down (intact) separate from the aircraft...absolutely NOTHING the pilot could have done..VERY SAD and VERY UNFORTUNATE..for whatever reason Reddit pulled down the  close up video and only shows the video after it broke apart..once again, just speculation on my part, I was assigned to the Army Safety Center, taught the Army's Accident Investigation Courses and was an Accident Investigator for 3 years....This is just SPECULATION on my part based on NOTHING MORE than the video I saw, but I WILL tell you that those "professionals" that are commenting on the news agencies and the Youtube armchair quarterbacks are talking out of their azz..Will be interesting to see what the NTSB comes up with, if I were on the GO-Team, after seeing that video, my first priority would be to make sure we find that tail rotor gearbox.. I've attached a picture of the Bell 206, you can see that there are only (2) mounting point that attach the transmission to the Pylons that are mounted to the aircraft...not a whole lot holding it in place..but they did not fail.

Edited April 18 by Matthew P