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Chopper accident, Cooktown Qld


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If reported correctly, neither vortex ring state nor dynamic rollover were a factor. For vortex ring state to be responsible the heli would have to be close to zero forward speed and the results would have been a lot worse, if it were a dynamic rollover event then the rotors would have had to be turning and again the results would have been a lot worse.

 

 

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The rotors must have been spinning, news footage tonight shows that the main rotor shaft and rotor head missing. By the looks of the panels around the mast area seem to indicate it was ripped out.

 

 

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Could be right there Wayne. Just one of the probs you could face if you fly "ceiling fans".

 

Personally, i'm not a fan of them. Too many moving parts that all have to do the right thing, to try and keep you safe.

 

 

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News updates on TV earlier tonight said the heli was hovering on/at the rock while persons were boarding when the rollover happened. They were surveying areas for a potential helipad site..they said.

 

 

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Guest Maj Millard
News updates on TV earlier tonight said the heli was hovering on/at the rock while persons were boarding when the rollover happened. They were surveying areas for a potential helipad site..they said.

I don't think they've found it yet !........

 

 

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They did say it was gusty wind and that the helicopter was affected by a strong gust, turbulence on the lee side of that ridge, bit hot and humid with 6 on board, sink, yank on collective rotor rpm drops little too much and oopsey tripped over that bloody big rock.

 

 

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I would have thought that a dynamic roll over was more plausible than a wind gust.

I'd agree - and worth keeping in mind that folks tend to confuse dynamic rollover and ground resonance. B206s don't suffer ground resonance, they don't have suspension to the skids, the imbalance of which is the primary driver for ground resonance.

 

Any helicopter can suffer dynamic rollover, it is basically a situation of pilot error where you get a skid caught on something and make the mistake of continuing to try and make the machine travel in that direction, a trip-over, for want of a better description.

 

The dreaded 'vortex ring' strikes again.

I doubt it in this case, vortex ring results from descending into your own rotor wash.

 

Could be right there Wayne. Just one of the probs you could face if you fly "ceiling fans".Personally, i'm not a fan of them. Too many moving parts that all have to do the right thing, to try and keep you safe.

Hey planey, you have wonderful input into all things fixed-wing but if you don't understand the wonderfulness of rotor-craft ... please stick to telling us about planks ...

 

They did say that the engine was switched off at the time. Not sure what the weather was like up there but was a horrible windy day here today.

As with any aircraft, helicopters are affected by downdrafts but they are not much affected by turbulence. I'd not hesitate to land on that particular outcrop after manoeuvring here, there and everywhere to find a place where the skids settle happily and are properly supported on three points which adequately straddle the CG. Though I'd certainly be very reticent about trying to pick up pax in the hover. Communication with them is very difficult unless it is well planned in advance, but by far the greatest risk is that pax get excited and tend to leap about, jump and grab. Fear is their driver, among other things they think they might get left behind. To load pax in the hover requires them to behave with great discipline and be very gentle as they apply their weight to the craft. When experienced field surveyors, shooters, mineral samplers, for examples, board in difficult terrain they do it so gently that apart from the slightly increased power requirement the command pilot will often have to check they have actually boarded - with inexperienced pax there's no doubt about it!

 

Don't let the truth get in the way of a good story.

Yo

 

They did say it was gusty wind and that the helicopter was affected by a strong gust, turbulence on the lee side of that ridge, bit hot and humid with 6 on board, sink, yank on collective rotor rpm drops little too much and oopsey tripped over that bloody big rock.

If it was 6 PoB then it wasn't a Jetranger (5 seater), it would have had to be a Longranger (7 seater) - but it looked like a Jettie from the only pic I've seen. The Jetranger has the RR GM Allison C20 turbine of 324hp (transmission limited), the Longranger is ... testing my memory now, about 600hp, also limited to something less than that by trans.

 

This kind of incident usually results from pilot inexperience or lack of horsepower in the hover. I'm not casting any aspersions, I have no idea of the pilot's experience. A need to hover tail into wind can also make it very difficult, it consumes lots of hp via the tailrotor, and greatly affects the attitude of the fuselage in the hover - remember you're flying the disk, not the fuselage .... Sometimes tail-into-wind is essential to keep the tailrotor clear of inexperienced pax, foliage, or terrain.

 

In my opinion you could forget the "turbulence on the lee side of that ridge", I don't believe that any heli, in reasonably experienced hands, would have a problem on a lee side in anything short of Cat 4 conditions. As you rise into, or descend into, the hover you feel the turbulence or downdraft and can manage it, or cannot - and that's the decision time. If you've moved onto the phase of loading pax then presumably all was well.

 

However, if you're loading pax in desperation to get them off a pinnacle in worsening conditions then you made that (bad?) decision ... one of our well indoctrinated instructional aspects is that if weather is really bad right now, just wait a few minutes or half an hour and it will change - pilots of all aircraft types could benefit from keeping that in mind.

 

"yank on collective rotor rpm drops little too much and oopsey tripped over that bloody big rock." This comment would suggest pilot inexperience - I'm not agreeing or not, but there's no such thing as 'yanking' on collective where turbines are concerned, unless the pilot is very inexperienced, and recently converted from piston to turbine. With turbines sm-o-o-o-th use of collective is the signature of a mature operator. Nonetheless I'd agree that it looks like dynamic rollover from perhaps having descended inadvertently and tripping on an irregularity of that bloody big rock. The way that this sort of thing often happens is because the PiC is on the right hand side (in many helicopters, including B206 Jetranger, to allow use of frictions on the collective which frees up the pilot's left hand for changing comms freqs, so that in the hover in CTA you can change from ground to tower to departures etc - very difficult to do otherwise, until you have enough practice to hover the aircraft with the cyclic held between your knees). The rotor spins anti-C viewed from above, the tailrotor CP is above the CG so in the hover the left skid hangs low, and the tail hangs low, so the left rear skid is very vulnerable to catching on something, add an anxious pax grabbing on to board the back seat on the left ....

 

And - because the pilot is on the right, the pax tend to load from the left, unless told to do otherwise. The experienced pilot makes his pax load from the right rear first, then the left ... not always possible on a pinnacle of course.

 

The lesson is learned in less than a second, that's how long it takes from being happily loading your pax, to a situation of complete disaster, and often in a fairly remote location. A thought for everyone, have you got your First Aid Kit up to date? Possibly review the Survival thread?

 

Cheers all, it's my birthday today, I survived another year!

 

 

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Watched a lot of movements at Shute with low time pilots, saw a lot of real scary sling work as well. Rangers are not my strong point but did a lot of work on Bell 47 and R22 when i was at Camden,put a few hours on them, loved the 47 hated the 22. Have quite a bit of experience on the Alison(now RR) B17 from the Nomad.

 

Bit annoyed when i tried to pick up and fly away with a 47 like i could with a fixed wing and found i couldn't.

 

Just about covered every square inch of Camden Airport with Miles laughing his head off next to me while trying to hover when i used my ' I've read the book' approach.

 

 

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