Mi-8 Crash in Gelendzhik, Russia

[Tiger G]

As stated in the title:


LiveLeak.com - Mi-8 Crash in Gelendzhik, Russia


If it's another oldie,. I'll delete.

[tottigol]

That is a textbook example of Vortex Ring State if there is one.
Impact did not seem that bad, tail boom should not have separated like that.
Pilots were likely killed by fire and smoke inhalation.
Emergency/Rescue Fire trucks crews seem incompetent at best.
God save their souls.

[fijdor]

No doubt about it.

JD

[Vertical Freedom]

RIP to the Blessed lost Souls

Air speed Air speed Air speed...it is Your life line, never ever loose it unless You have too ie; slinging, filming, confined area :ooh:

[Max Contingency]

Fascinating video - Sympathies to crew and relatives

Here's my take on it.

Moving backwards in an OGE hover (possibly a high DA as well) is always a dangerous regime requiring high power. Moving backwards through zero airspeed requires even more power and then stopping that rearward movement requires more power again.

The pilot did push nose forward to arrest the rearward movement but the coning angle of the disk and the change in speed of the tail rotor (assuming the camera frame rate was constant) shows exactly the point at which the available power ran out and the Nr began to droop. That left the pilot with two options:
1 Keep pulling
2 Hold the collective at that point and stuff the nose forward 30 to 45 degrees and possibly kick the tail to reduce power requirement.

Option 1 was fatal, Option 2 'may' have given a fly away with the height available. The pilot, probably acting on instinct alone at that point, chose option 1 and leveled the aircraft when he knew he would hit the ground.

How many flag flying accidents is that now?

[evergreen139]

My condolences to relatives and friends...

to Max Contingency (http://www.pprune.org/members/16295-max-contingency) , have to admitt , that normally civil pilots (Mil-8) never do a pitch change in that range (30-45 nose down*)
"Air speed...it is Your life line" agree totally

I know, it's not good to blame dead... but:
1. The CRM hardly exist in that helicopter ( I suspect the copilot kept silence to the end, even if he knew WHAT was his "king" doing)
2. The capt is the King, the words of a king is a law, so cpt should be quite near the king (it's not always like that, but up to 80%).
3. Lack of basic knowledge of the capt. and maybe too exaggerated self confidience (maybe).

What will the investigation do?
the fully operative helicopter crashed by single person leaving 2 pilots dead (Capt Kramarov V.M. and copilot Khodak I.A) and injured flight mechanic ( Kosenko G.B.).
Will the investigation implement something new after this crash? I don't know...
P.S. of course if there were some problems with controls, then the "CRM" is not the case afterall.

update: all 3 dead by now... RIP

[Peter-RB]

What a very sad vid to watch, made even worse by the reaction time of the emergency crews, what a dreadful way to end any flight, RIP who ever they were.

Peter R-B
Lancashire

[212man]

The airport is at sea level (88 ft) and the recent temperatures are likely to have been in the 28-32 C range. Can a MI-8 really not hover OGE with only 3 crew on board, in those conditions?

[hueyracer]

Even with -20°C….once you´re in VRS, you´re in VRS…….

[RVDT]

The counterintuitive trap of VRS -- (if in fact it was the issue)

It's simply about catching up with your downwash.

In a lighter aircraft with a low disk loading it is thus easier to encounter.

Power needs to be greater than ~ 20% and if you do the numbers on this aircraft
it could be as low as 250 fpm!

[fijdor]

212man the problem here, is not the aircraft inability to stay in a hover, it could, but the fact that he got caught in VRS coming down for landing. Did not recognized the situation fast enough to correct it.
RIP.

JD

[Flying Bull]

Hi all,

seen the video now and my 2 cents...
Things went really wrong after initial touchdown, cause the collective wasn´t lowered and the bird went up again.
Reminded me of some other accidents....
Even so it seems to be a natural reaction, to get away from terra firm in a flying machine - once down it´s often a good idea to stay down, especially if parts starts to disintegrate - and if in doubt - keep it down.

Fly safe

[hueyracer]

This is a TYPICAL reaction of an aircraft to VRS.

The aircraft gets in to a high rate of descent; the pilot does not realize what´s happening.

When he approaches the ground, he tries to recover the RoD by applying collective, which then increases the Rod.
Instead of lowering the collective and dropping the nose, the pilot pulls max pitch…….then the aircraft touches the ground…the VRS stops…and the pitch is still high……then the aircraft gets airborne again, but the pilot usually applies full pitch in the VRS without applying full pedal (as this is not necessary in a VRS)…..as easy as this….

[Reely340]

@hueyracer
interesting analysis. Between your lines I read, that while misbehaving during VRS (pulling pitch) he could have partly saved the situation had he dumped the pitch at least directly upon impact:

He'd have a ruined landing gear or two, but he'd not have bounced up again, and even if the tail broke off from impact, that wouldn't have been an issue as with the pitch fully down there won't be any torque to counter.

What's your guess: If he'd have slammed the pitch down upon impact would he'd still have keeled over?

[212man]

Why do people always associate high vertical descent rates with VRS? He simply ran out of power - as Max Con has already commented.

[Reely340]

Being a piston only newbee, how can that be?
I've been told that turbines are merciless engines, which easily can shred any gearbox and rotormast, unless meticulously controlled by PIC monitoring the torquemeter.
Except for brand new electronic fool proofed TOT_and_TRQ_limiting_FADECS one can easily overtorque a turbine helo's gearbox.

Hence my image would be that in the given scenario there cannot be any lack of power on a "near empty weight" turbine helo (at least in a Mi8 operating @88ft(!) MSL w/ just three occupants and 32°C OAT) the worst result would be an immediately due turbine HSI. :ouch:

Which must mean it was VRS, not?

PS: I HAVE experienced "lack of power" together with a buddy of mine practizing in an S-300C at apparently very high DA (stupidly gassing up before the flight, conditions were very humid, light drizzle) where one is literally fenced in between OAT mandated max. manifold pressure and desired Nr. We literally were fighting to get it to a 3ft hover, flying the square.

edit: all pages I googled regarding VRS state claim one needs to sink in excess of 300ft/min w/o significant lateral speed to be able to encounter VRS. That crash becomes even more weird: was that helo descending faster than 300ft/min before catching VRS? How can a twin at sealevel with +6000lbs useful load lack power to hover? Maybe he had a Hummvee loaded as cargo while doing the banner flight, but I'd doubt that.

[vfr440]

Russian helis don't have a tqmeter, so you don't know how much tq you are pulling until the NR droops; then you do. - VFR

[MightyGem]

Why do people always associate high vertical descent rates with VRS? He simply ran out of power - as Max Con has already commented.
Exactly. The ROD wasn't high enough for vortex ring.

[malabo]

All the finest minds in the helicopter world looking at the same high quality video and we can't agree whether it is settling with power (insufficient power to stay in the air) or Vortex Ring State (VRS, recirculation of air..).

My opinion is that it was VRS. Judging from the smoke afterwards, the helicopter flying backwards was going downwind, then it pitched forward to stop (but still going backward in relative air) and the crew lowered collective to descend. Classic VRS entry conditions. You can see the aircraft accelerate downward (ROD looked VRS to me, don't forget it was only up about 300' at the time).

I'm ruling out settling with power simply from what I know of the performance of an empty Mi-8 with low fuel, three crew only on board, at sea level. I just can't believe they would have had any shortage of power to cause them to fall out of the sky. Perhaps a Mi-8 pilot can verify. Light weight is also a factor in VRS entry condition.

[RVDT]

And to add -

VRS is worst at about a 70 degree relative approach angle apparently.

http://www.copters.com/aero/pictures/Fig_2-82.gif

As mentioned before this aircraft at light weight due to its low disk loading
could easily encounter the onset at as low as 250 fpm i.e. only ~ 4 fps.

[JohnDixson]

RVDT, the chart is in direct conflict with Ray Prouty on this subject ( see page 102 ). His book is certainly in agreement with the various VRS tests on SA machines ( and one other ) that I have been involved with. Curious.

Thanks,
John

[cpt]

The point is that, because we hardly meet VRS in the course of our pilot carrers, we tend to store it in the back of our mind, that makes it even more treatorous.... wasn't it the case in this late 332L2 accident in the Shedlands ?

Just for the sake of experience sharing, I recently put myself in a VRS ( I already have experienced peharps 3 or 4 VRS all along my helicopter flying years)

I was training a "young" S76 pilot, speed variations with one engine in the "manual-trim" mode and the "ALT" function engaged to maintain a constant altitude.
at one stage, our target was a speed reductiion to 60 Kts, but the preset torque was obviously too low, IAS dropped increasingly quickly below 40, the coupled "ALT" couldn't maintain altitude and we started to sink with our speed reducing in a blink of the eye, to almost nothing, then all the symptoms followed in sequence, vibrations, sluggish reaction with flight controls (it made it harder to build up speed again) and down we went.

We started at 1500' and managed a recovery just below 1000'... I must admitt I wasn't very convinced about the VRS scenario in the "Shedland" case, now .... I understand much better how this could have happened, sadly, at much lower height.

I also can say that the S76 simulator reproduces the VRS very faithfully...

Once again the popular wisdom quote saying that your horse will kick you when you will not expect it, is verified with Helicopters and VRS.

[Helilog56]

On occasion while instructing VRS will be demonstrated for any student or pilot that wants to gain the real world experience. I will not even consider doing it less than 4,000 agl as vertical descents can be in excess of 6,000 fpm....which can leave minimal time to recover when deep into VRS.
I am dismayed by the lack of knowledge from pilots that can not see the difference between VRS and settling with power (FAA term), which really should be insufficient power.....it is still taught in the US, that they are one and the same....!!!?!?!

[RVDT]

cpt,

Value for money - 2 traps in the same flight!

[fijdor]

In reference to Helilog56 post, here is what TC (Transport Canada) has to say about VRS and SWP. Not the whole thing but part of it.

JD

You should note that an increase in collective alone may not result in a recovery and indeed may only serve to increase the rate of descent. This increase in blade pitch will cause the vortices to intensify in strength and will result in a more rapid descent.

There are some uninformed pilots who use “settling with power” to describe vortex ring, in fact some publications use the terms interchangeably. Confusion results when symptoms are related that do not describe true vortex ring but rather describe “settling with insufficient power”. This may occur when a pilot attempts to arrest a rapid, low power descent only to find that he has insufficient power available to bring the helicopter to either a hover or a no-hover landing without exceeding the engine limits. However, this is not a vortex ring situation.

Another situation, ‘over-pitching’ is often misinterpreted as vortex ring. This is where the pilot rapidly increases collective considerably and the engine cannot produce enough power to overcome the large, swift increase in drag on the rotor system. The result is that the rotor system quickly slows down and loses efficiency causing the helicopter instantly to sink. Again, this is not vortex ring.