PPRuNe Forums - One down in Mexico

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One down in Mexico

longer video:

Bet the driver of that van went and changed underwear as well!!! :eek::eek:

To say nothing of any passengers in the van, it is almost unbelievable how the rotor blades didnt chop it to pieces before he managed to accelerate away .

Lot of people thanking lucky stars after that

Can any of you rotary pilots offer an explanation for this loss of control? By the way, I think the overhead road sign “Feliz Viaje” in the video doesn’t apply in this case.

Looks like a tail rotor/drive failure to me.

Mog

It does look that way but until it hits the ground I don't see anything untoward from the TR slowing down or moving unnaturally. Looking at his manoeuvre I wonder if he was heavy, hot n high and put a bootful of rudder in as he came to the hover and just ran out of tail rotor authority? Just a guess....

I go with running out of pedal.

Regarding running out of anti-torque pedal, I stumbled across this post from long ago by Nick Lappos which is worth a repost.

Quote:

If you slip down in Nr by even a bit, it can have a double effect. Here's why:
The thrust you deliver from the tail rotor creates the anti-torque, and is proportional to the pitch setting and the square of the Nr. If you reduce Nr by 2%, you reduce the thrust by 4%, which could get you close to limits in some cases.

The anti-torque that you need is proportional to the main rotor torque. If you droop Nr, the rotor needs the same power, but power is torque times Nr, so for constant power, the Main Rotor torque must go up. For a 2% droop in Nr, the torque will rise by 2%, and the anti-torque needed wil have to rise.

Thus, a given droop in Nr produces non-linear effect on the tail rotor margin.

A third effect is the need for the helicopter to point into the wind, like a weathervane. When crosswind, this effect is maximized.

Another effect that can play is vertical maneuvering. Note that a slight torque rise (manifold pressure for recips) will require a corresponding anti-torque response to maintain heading. If you nudge the collective upward and droop the Nr a bit, you can easily carve 5 or 7 knots off the side flight capability of the machine. For a hairy flare at the bottom of a too-fast approach, the main torque can be pumped to 10 or 15% above hover torque, and the tail rotor can be saturated.

There really is no such thing as Loss of Tail Rotor Effectiveness, BTW - for a given density altitude, the tail rotor always produces a given maximum amount of thrust and a given maximum effectiveness, it is just that it can be swamped by main rotor torque rises, and by crosswind effects. Generally, only marginal tail rotors experience LTE, and the vast majority of LTE events are experienced by only two types of helicopter. LTE is not a pervasive helicopter problem.

Whatever the issue in that video, I think the pilot, after realising he was in trouble low down, went for the paddock when out of nowhere comes a bus full of tourists and it's too late. Glad there were no major injuries.

Quote:

Originally Posted by Mogwi (Post 11102086)

Looks like a tail rotor/drive failure to me.

No way. Loss of TR drive would result in a much faster rotation than what is seen in the video. I'm with megan on this one, he ran out of pedal.

Heavy, aborted takeoff, stopped and turned out of any wind while still 'way out of ground effect. Settled with power, kept pulling the NR down so consequent loss of tail rotor authority and uncontrolled rotation. Might have made it without that pesky van in the way.

Thought the takeoff point was the football pitch, and the paddock with van was just a convenient place to crash.

mexico, previous ride might have been a 407, and he would have gotten away with it in that.

They missed a bus, powerlines, lighting poles, car park, livestock, bystanders and a compound.

Mjb

Quote:

Originally Posted by mickjoebill (Post 11104485)

They missed a bus, powerlines, lighting poles, car park, livestock, bystanders and a compound.

Mjb

That should make the pilot a hero in the media then! (Pity there wasnt a nearby school to miss too)

Welp, we can't all be Chuck Yeager...

It looks like the pilot reduced power after the initial take off and the yaw reduced mostly (sideslip helping keep it straight). Wonder if he might have been able to fly that out tbh, but he slowed to put it down with increasing yaw again. Hard to watch and not shout “keep it down” after that first ground contact.

Quote:

we can't all be Chuck Yeager

To be fair he's emulating Chuck Yeager, in as much Chuck threw away a F-104 because his ego exceeded his ability and nearly lost his life in the ejection.

Ohhh, dear Megan. Close out Tik Tok for a moment, will you? Look sweetie, you have to take into consideration the totality of C. Yeager's life and accomplishments. I realize that they all happened well before you were born, and so therefore don't count, something that is typical among you millennials. (Hell, for that matter the Beatles happened before you were born, too, and you probably consider BTS to be cutting edge.) And so you took one screwup of Yeager's and used that to invalidate his whole career and equate it with that of some bonehead helicopter pilot who couldn't fly his way out of an LTA event, eh? That about right, missy?

Testimony to the toughness of Mil gearboxes - that mangled main rotor appeared to be still turning under power even after the machine had stopped moving?

Quote:

Originally Posted by Torquetalk (Post 11104875)

It looks like the pilot reduced power after the initial take off .....

He didn't take off. It was an aborted landing short prior touchdown at the soccerfield for unknown reason. There is a video somewere but I couldnt find it right now. The turning starts as soon as he pulled obviously a lot of power.

skadi

Quote:

Originally Posted by skadi (Post 11104978)

Looks like he should have aborted the landing a bit more.