What in the world is wrong with this helicopter?

[Rubycon]

I don't like helicopters; as a matter of fact I simply abhor them...

BUT! I have to wonder what is going on here!

Almost (yeah almost hehe!) feel sorry for the little fella!

http://www.youtube.com/watch?v=sACBKBeykZg



Thank goodness no one was hurt. This could have ended badly.

 

[Crono]

That's what happens when you substitute epoxy with Elmer's.

 

[bfdd]

it looks like a piece of junk, that's what's wrong with it.

 

[Rubycon]

That's what happens when you substitute epoxy with Elmer's.

Or forget to correctly lube the shaft where it goes through the tight area.

 

[Crono]

Or forget to correctly lube the shaft where it goes through the tight area.

Honestly, I'm not trying to take my mind to a dirty place, but...

 

[mmntech]

Serious answer? The rotors weren't properly balanced.

 

[SKORPI0]

http://www.bbc.co.uk/news/world-latin-america-17150747

 

[Crono]

Serious answer? The rotors weren't properly balanced.

Agree with that.

It's like having an unbalanced centrifuge or washing machine, but a whole lot messier.

 

[Rubycon]

Honestly, I'm not trying to take my mind to a dirty place, but...

Oil attracts dirt so naturally those places in and around machinery are quite dirty.

http://www.bbc.co.uk/news/world-latin-america-17150747

:'(

Serious answer? The rotors weren't properly balanced.

Yes but this happened right after landing so something must have gone wrong at or shortly after that time. Scary to think (possibly) something simple can go wrong/break causing catastrophic failure like that.

Or it was just not properly maintained?

I don't know those things scare me.
A lot.

 

[lxskllr]

If a chunk of rotor broke off in flight, you might have a reasonable smooth ride, while shaking itself apart on the ground. I dunno. I don't know much about helicopters.

 

[spidey07]

Agree with that.

It's like having an unbalanced centrifuge or washing machine, but a whole lot messier.

Nope. The effect is called Ground Resonance and it's always a concern with a helicopter. The pilot was supposed to take off when that happens, not sit there and let it shake itself to pieces.

 

[CZroe]

They said on TV that it was some well-known ground reverberation phenomenon.

 

[IronWing]

...ground resonance can occur with a rotorcraft when the spacing between blades becomes irregular or the damping system, including drag hinge dampers, landing gear oleo struts, or wheel tire pressure, is operating out of limits.


http://en.wikipedia.org/wiki/Ground_resonance

Sidewall pressure, it matters.

 

[Crono]

Nope. The effect is called Ground Resonance and it's always a concern with a helicopter. The pilot was supposed to take off when that happens, not sit there and let it shake itself to pieces.

From wikipedia:

Ground resonance is precipitated by a shock to the aircraft arising from excessive motion of a rotor blade in its plane of rotation thereby moving the rotor center of gravity from the axis of rotation. Inadequate damping allows the rotor center of gravity to spiral away from the rotor axis of rotation, causing the rotor to generate unbalanced rotating moments beyond the compensating ability of the damping system.

Sounds like resonance causes it to build up, but the initial "shock" is probably from an unbalanced rotor.

 

[dmcowen674]

What in the world is wrong with this helicopter?

I don't like helicopters; as a matter of fact I simply abhor them...

BUT! I have to wonder what is going on here!

Almost (yeah almost hehe!) feel sorry for the little fella!

http://www.youtube.com/watch?v=sACBKBeykZg



Thank goodness no one was hurt. This could have ended badly.

Also good news is that it will never do that again.

Bunch of scrap metal now

 

[caddlad]

The jesus pin sinned?

 

[LTC8K6]

Yes, it is ground resonance. You must either take off, or shut down quickly when it begins. It can happen to any helicopter that has it's rotor spinning while on the ground.

http://www.youtube.com/watch?v=0GEj69NANc8

 

[BoomerD]

Wait...you mean it's not supposed to do that?

 

[Fenixgoon]

Serious answer? The rotors weren't properly balanced.

probably. wish i knew more on rotary aircraft.

the rotor assembly is INCREDIBLY sensitive to weight distribution. we're talking a few grams can make a huge difference.

 

[Bignate603]

From wikipedia:


Sounds like resonance causes it to build up, but the initial "shock" is probably from an unbalanced rotor.

An unbalance isn't a shock, it's a steady state condition so no resonance would be needed to cause a high vibration. The shock most likely came by bouncing against the landing gear.

From the description ground resonance is something that causes a rotor blade to swing in plane with the other blades, causing the center of gravity to shift away from the center of rotation. If that happens (and there's not enough damping in the system to dissipate the vibrations) the displacement between the center of gravity and center of load causes a centrifugal load to form, pulling the rotating assembly in that direction and causing the center of gravity to pull even farther away. This becomes self sustaining and will continue to build until the forces are so great that it tears the helicopter apart.

 

[spidey07]

If youre a skate boarder you know what resonance is. Same concept.

The wobbles are harmonic resonance. A force fed loop that only gets stronger. I've crashed and burned doing high speed skate boarding. Your body. The dampener becomes a force fed loop. Once you get them little can be done to stop them.

 

[Bignate603]

If youre a skate boarder you know what resonance is. Same concept.

The wobbles are harmonic resonance. A force fed loop that only gets stronger. I've crashed and burned doing high speed skate boarding. Your body. The dampener becomes a force fed loop. Once you get them little can be done to stop them.

Motorcyclists know it as a tank slapper, jeep drivers known it as death wobble. Once a resonance gets started it can spiral out of control very quickly.

 

[CZroe]

Motorcyclists know it as a tank slapper, jeep drivers known it as death wobble. Once a resonance gets started it can spiral out of control very quickly.

Yup. Scary stuff. On the motorcycle, I get a slight but increasing headshake after about 1,500 miles on any new tires when I remove my hands but I usually carry on to 7,000 miles and I've never had a full-blown tank slapper.

 

[MichaelD]

You are all wrong. Can you not hear the Swahili/Aboriginai/Bun-gaiya-wompelee language being shouted in the background? Third World country equals substandard maintenance procedures. No technical orders dictating exactly how to maintain that chopper means that it never was. And if there WERE T.O.s, the natives argued about the goat/weather/demon spirit possession of the tools or hanger door instead of fixing the damn thing.

Silly backwards people.

 

[Gerle]

Hangers are for clothes, hangars for aircraft.