Dynamic Rollover Video

[Darren Hughes]

 

If ever there was the perfect video to highlight what the critical rollover angle looked like, this might be it. Aside from the fact that they're messing with the RPM pretty dramatically, maybe it's stuck pedal training. If you pause at 22 seconds you can see that he has a massive amount of left cyclic held in, probably hoping it will bring it back down for him. But, as you can see it only makes it worse. Probably not helped by the rolling on of the throttle either at the very end.

 

LOWER COLLECTIVE PEOPLE!!

[Lindsey]

Thanks for the lesson!!!

[Pohi]

Dear Lord,

 

I just about lost my breakfast. That has to be the slowest train wreck ever.

[TimW68]

I've seen a few of these accidents, and the only corrective action I've ever really heard is"lower collective". While I certainly know that is the most important thing to do, is coming back against the roll (after lowering collective) with a very gentle and small cyclic imput helpful or just down collective? Forgive me I have never trained for this and it's all just hypothetical. My God, just one more thing a student can do to ruin a CFI's career.

 

Happy Holiday's All

[Wally]

Once at the critical angle, no amount of cyclic alone can reverse the roll. The disc is producing lift, which causes the roll. Your only hope is to get rid of that rolling force, put the collective down, before the roll moves the CG to the tipping point. Once that happens, even reducing lift isn't going to prevent the accident.

This accident film is a vivid lesson in why you land, or takeoff, stationary in relation to the ground.

[JETTSET99]

Guys your forgetting one thing ,once you get at a certain angle lowering collective isn't going to do it because now you have another problem very similar to P factor a airplane has with its propeller on take off,even with zero pitch you have the airfoil traveling with a high induced angle of attack due to the rotor disc at a high angle thus acting like pitch producing lift more thrust produced if in windy conditions, and the lower blade not as it falls threw lower induced angle this might account for this roll over didnt seem like he had a stuck skid im sure he lowered the collective at some point unless he pulled it to get airborne?

[JETTSET99]

Another thing I notice listen to the motor just before the helicopter settles you can here it lower its rpm and watch the pilot and pass as the touch down they jerk to their right( so the first touch down seems to be due to low rotor rpm) then another rpm increase is heard just before the blades impact this can be the cause leading to the rollover?

[RockyMountainPilot]

Guys your forgetting one thing ,once you get at a certain angle lowering collective isn't going to do it because now you have another problem very similar to P factor a airplane has with its propeller on take off,even with zero pitch you have the airfoil traveling with a high induced angle of attack due to the rotor disc at a high angle thus acting like pitch producing lift more thrust produced if in windy conditions, and the lower blade not as it falls threw lower induced angle this might account for this roll over didnt seem like he had a stuck skid im sure he lowered the collective at some point unless he pulled it to get airborne?

 

The tilt of the rotor does not cause a high induced angle of attack. When the collective is lowered completely, the AOA averages to around zero. The tips will have a negative AOA and the roots will have a positive AOA, but very little total lift is being produced.

 

If you have a static helicopter sitting on the ground and you tilt it, you need to get the CG of the helicopter past a skid to tip it over. It has been a long time, but I think the R22 is 44 degrees. Under power, the max tilt of the rotor is 18 degrees I believe. So, depending on how much power you have applied, the tipping point is somewhere in between. If you have a small amount of collective pulled, it might not go over until 40 degrees. If you have a lot, it might go over at 20 degrees.

 

The guys in the video actually did lower the collective. You can tell this because they were at around 40 degrees and the disc was tilted way in the direction of the roll. However, they did it too late and had already tipped to the static tipping point. It looks like they went just to it and stopped for a second. They were right on the tipping point, so if they reacted just a fraction of a second quicker, they would have rolled back on the skids. Actually, they might have put the collective down, but then pulled power back in at the last second now that I watch it again.

 

Anyway, hover high and move slowly close to the ground.

[Goldy]

Darren- Excellent video. There is a reaction when you set it down a bit too hard to pull it back up and try again. I know, I've caught myself doing it. When he first set down on one skid hard, he should have just lowered collective, let it bounce if you have to.

 

I think they did try to push the cyclic over to compensate, but didnt lower collective enough / or early enough.

 

Great teaching tool to show how fast it can all go bad.

[Daniel L. Lieberman]

Where is the link to the video? It sounds interesting.

[67november]

Where is the link to the video? It sounds interesting.

 

Click on "Rotorway Crash" in the first post

[Daniel L. Lieberman]

Thanks.

[Fling Wing Skywalker]

Guys,

 

Jett Sett called it. This was new Rotorway pilot who was not use to flying without governor. She had most of her previous training in the R22.

 

She was encouraged to get some RW transition training but opted not to and attempted to fly this ship by herself. The Rotorway helicopter itself is very forgiving with a properly trained pilot, but not to someone who has not had proper transition training.

 

Watch the video again and you can hear the rotor and engine rpm decay over time. If she would would have increased the throttle after she picked up the ship she would have maintained the rotor RPM. Most pilots pick the Rotorway up using the following procedure to avoid this situation.

 

You first get the ship light on it's skids with the rotor and engine rpm in the upper band of the green on the guages. Then for final lift off you are instructed to leave the collective steady and continue to roll in more throttle. After you become airborn you then adjust throttle and collective accordingly to maintain engine and rotor rpm in the proper "green range". This technique works like a champ, but is much different that what most students learn in the R22.

 

Thanks

[captainkevlon]

Fling Wing Skywalker

 

Sorry man, but you're wrong...

 

This was a 74 year old private pilot in England...he has 195 hours on type

 

What you all witnessed was the result of a senior chap, tired through flying all day, paying scant regard to wind direction, rpm and general helicopter handling...

 

It wasn't the first time he'd wrecked the same machine either...

 

What do they say..."you can't teach an old dog new tricks" !

 

Kev

Edited January 21, 2010 by captainkevlon

[Hedge36]

Kev is correct: http://www.aaib.gov.uk/publications/bullet...62f__g_esus.cfm

[Jimsy]

Hello guys, I am a novice pilot, trained and rated on R22.

As soon as the video started I noted that the RPMs where decreasing as all of you; I'm happy of not having missed this vital factor out.

Nevertheless as the video rolled I started asking myself what I would have done in that situation.

Probably, as soon as the skid pivoted the aircraft, I would have tried to lift the whole craft up and take it back to a hovering, before attempting the touchdown again from scratch.

Do you thinks this would have been a sound manoeuvre?

Were the RPMs too low to lift the chopper back up, even giving full power?

Thanks for any comment.

[Hedge36]

In all likelihood, yanking the collective in that situation would have exacerbated the situation even faster. Remember that his rotor RPM was probably not in the green; trying to get the bird off the ground would create a torque response which the tail rotor (which was also not producing as much thrust as it should) wouldn't have been able to overcome - result: more skid pivoting.

 

If his MR was up to speed, getting off the ground would probably have worked so long as he didn't yank the collective too quickly (which would make the MR RPM droop and likely result in a nasty bounce and perhaps a rollover anyway).

 

The main lesson in this one, which isn't as obvious as it may seem, is that MR RPM is your lifeblood in all phases of flight.

[Jimsy]

Thank you Hedge36.

So summing all things up may we say that the following are true?:

- the first mistake was to let RPM to get too low

- in the event of finding ourselves in that situation the only way out would have been to lower collective before the centre of gravity went out of the footprint of the skids

- after that there would probably be no way anybody would have saved the craft from rolling over