Helicopter crash Hudson River 1

[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

 

[LittleInch]

Behind a pay wall unfortunately, but I get the gist. It did sound like a bit of a mom and pop operation.

The quote I heard when he said the pilot only had a few minutes of fuel left was rather alarming. He also seemed to be flying pretty fast for a tourist flight.

 

[TugboatEng]

There is a picture of the rotor still attached to the transmission with the mounting hardware on it still. It looks like it tore off a chunk of the airframe.

There is also a picture of the engine. In this design, the exhaust outlet is on the center and the combustor/turbine and compressor are on opposite ends. The compressor section is broken completely off. That is a possible source for the energy to break the airframe.

 

[Sym P. le]

From a New Zealand report here, a typical powerplant layout.

Also, from the first photo, it appears that the mast is significantly bent.

I noticed from the crash video that the entire drive bay was empty, leaving mostly just the passenger compartment. Posted are four cropped frames (not all successive (two pairs)) from one of the crash videos just before impact.

 

[waross]

Years ago I was hanging out in a hotel in the Yukon territory. That's east of a cold part of Alaska, but colder.
An exploration helicopter crew was stationed at the hotel.
One day I was sitting in the coffee shop when a helicopter landed.
The pilot was watching the rotors slow down.
That was strange.
That pilot generally jumped out as the bird hit the ground and headed for the coffee shop.
He often left his mechanic to shut off the engine.
I wandered out to see what was happening.
When the rotors were almost stopped, the pilot jumped up and grabbed a blade.
It had a shallow crease about 1 1/2 inches long.
The radio antenna was shattered at the end and the metal tip was missing.
The pilot remarked;
"I was flying at about 120 MPH and went into a steep dive.
The wind speed bent the antenna upwards and the rotors dipped downwards.
The blade hit the end of the antenna."
The blade had to be replaced.
I heard a price mentioned of about $7,000.
One of the pilots working there had lost a helicopter.
He touched down too hard and the rotor dipped down and cut off the tail.
The inertia of what was left of the rotors flipped the helicopter over and it burned.
Fortunately the pilot was thrown clear.
The only part salvaged was a spot light that was mounted on the front of one of the skids.

Back to the tragedy at hand.
My first thought is that something startled the pilot (a bird perhaps) and he made an abrupt pull on the cyclic stick.
The rotors tilted and contacted the mast.
Other than that we have to wait and see.

 

[TugboatEng]

The damage is largely concentrated in the compressor housing. It looks like the centrifugal compressor disk burst. Can these over speed if the load is abruptly removed? Maybe a gearbox failure led to a catastrophic overspeed.

 

[mfgenggear]

The damage is largely concentrated in the compressor housing. It looks like the centrifugal compressor disk burst. Can these over speed if the load is abruptly removed? Maybe a gearbox failure led to a catastrophic overspeed.

So I worked with gear boxes similar to this design , while I am not an engine expert I have dealt with loose gears for gear boxes.
From this OG memory this prat and Whitney PT 6 engine. Or similar. 10K RPM.
multi staged gear box gears to reduce rpm 1500-2000 rpm. Typically if the gears fail.
Catastrophic failure the gears from the engine self destruct. Parts break with high HP and RPM. Notice how the web and wall
Thickness is noticeably thin.
Safety factor is not much. It's to reduce weight . But I don't like jumping to conclusions. Wait for NTSB findings.

 

[thebard3]

Found this picture this morning. I know nothing about helicopters, but I did hear a lot about 'mast bumping' when it first happened. Does this picture suggest that both rotors are broken at about the same length by contacting the tail boom?

 

[Sym P. le]

How the turbine held on, by a few threads via the combustion chamber. We can see this in a similar orientation in the crash video (frame grabs posted above).

 

[Sym P. le]

Does this picture suggest that both rotors are broken at about the same length by contacting the tail boom?

I don't think so. The videos clearly show the assembly twirling down intact. I believe the blades broke on impact though I could be corrected.

It continually amazes me the penchant for popular knowledge regardless of its senselessness. We already have a clear photo of the self-destructed compressor stage.

Captain Steeve has a frank discussion on this incident and helicopter/pilot frailties. Though he also covers more popular knowledge, he doesn't come to any conclusions and hasn't reviewed the latest images.

 

[waross]

If the assembly was subject to the impact load of the rotor hitting the boom, the inertia may have done the damage to the turbine.

 

[Sym P. le]

Rinse and repeat.

 

[LittleInch]

Found this picture this morning. I know nothing about helicopters, but I did hear a lot about 'mast bumping' when it first happened. Does this picture suggest that both rotors are broken at about the same length by contacting the tail boom?
View attachment 8248

Mast bumping is something I had never heard of before, but seems to be when the helicopter goes low G on the top of a climb or sudden dive and its where the rotor blades flex out of plane and "bump" into the mast or the main rotor shaft which then basically breaks off. This doesn't look like this as the whole rotor assembly and what looks like a fair bit of the gearbox has been wrenched off as one unit. tug posted a video earlier on and if you make it through the first 5 minutes has a good explanation of it.

 

[Sym P. le]