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Dynamic Rollover on Solo Consolidation (ALMOST)

Dynamic Rollover Solo PPL Correct Response Preparation

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#1 Heli1223

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Posted 14 March 2013 - 18:50

Hi everyone, I thought sharing my story as a PPL student in South Africa on a R22 will emphasize the importance of training and flying with a 'what if' mindset.

I did my pre-flight, started the helicopter, did the run-up checks, called the tower for clearance to cross over the one runway on my way to the so called 'grass square'.
This is the only spot in the area with no grass at all and was our departure point for circuit flying. It was a small square and the surface was of the dark reddish kind of clay type. There was no slope and no bumps, just a flat and even surface - perfect for someone doing their solo consolidation.

My instructor and I flew a circuit or two to make sure I didn't forget what flying a circuit meant...
Then he jumped out, walked off to the front and commanded I picked the heli up, so as to see I hover like required...

I started lifting the collective slowly but confidently, trying to feel for the moment when I am going to start having control of the cyclic. I concentrated on the balancing as best as possible, because I knew dynamic rollover will not be a good start to my training and career...as well as to the instructor standing close enough for flying debris to have an effect on his health...

The 22 started lifting its nose, skids lifting in the front...

At this stage I feel it worth mentioning that it was in the raining season and the 'clay heli-pad' was moist enough for the skids to start digging into it...obviously one side more than the other...and obviously the left side more (left skid low in the 22).

I was oblivious to all of this, because everything looked normal. I was JUST about to lift off in my imagination when I realized the helicopter felt 'stuck' to the ground a bit (while lifting the collective), so I continued lifting (at this stage it wasn't a conscious decision yet, it was more of an observation WHILE it was happening in the few split seconds it took to happen).

Suddenly the right skid broke free from the clay at the back and 'jumped' into the air, left skid still stuck...the helicopter started turning a little bit to the right side (law of least resistance) so I added pressure on the left pedal (instinct off course, because of not knowing what is actually happening in reality).
This stuck the left skid even deeper into the clay. At the same time I lifted the collective in a small jerking movement to get myself off the ground (this was a 'safety reaction' that I had built in myself for not staying too close to the ground, but getting away from the ground as to avoid drifting and causing dynamic rollover).
The movement was small because I had told myself to NEVER lift the collective in a sudden way more than a LITTLE bit. I guess thinking about it now it would be an inch maybe (at 6000 ft D.A.)...obviously to avoid dynamic rollover.

This caused the helicopter to start banking left and aft at the same time while I was fighting the motion as soon as I realized what was happening (because I though about the skids digging into soft surfaces at the back when flying solo before the flight) I wanted to dump the collective and get the aircraft on the ground, but it broke free at that instant and if I didn't start lowering the collective already by that time it would have developed lateral velocity and most probably I would have had a dynamic rollover, because I was very close to the ground.

The result was the helicopter just bounced on its skids with the cyclic far to the right to balance the helicopter enough to be able to put it down right side up...like in a 'power failure in the hover' exercise.

Before and while I was training I read the book 'Fatal Traps for Helicopter Pilots' by Greg Whyte and it made me think about things a lot more... I started thinking: "What if I had dynamic rollover sneak up on me, how will I recognize it and how long will I have to react? What will be the proper response?" And then I would make up a scenario where I would imagine me hovering and the skid hooked on something obvious and I didn't realize it until the helicopter started rolling more the more I lifted the collective. And I would imagine how I realized 'dynamic rollover is happening' and how I lowered the collective very positively although not OVER controlling but stabilizing with the cyclic to keep the helicopter level...
So this would be my though process more or less while playing out the self made scenarios to play the 'what if' game with.

If it wasn't for this way of thinking I am pretty confident I would not have realized what was happening and what to do...not in time anyways...because that whole sequence (where the skid got stuck and I wondered why the helicopter was struggling to lift) was in about 1 to 2 seconds from start to finish.

I hope this shows someone out there how important thinking ahead and playing 'what if' scenarios really are. That is what prepare you, otherwise it will just be a theory class in your minds eye, instead of a tool to prepare you for the real life situation.

In real life, there is usually a very short time to think, thus you have to know what to do already, especially in case where you don't realize what is happening until the last moment.


I hope someone benefits from this story.
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#2 pilot#476398

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Posted 15 March 2013 - 13:02

So....? Don't land on clay during the rainy season,...got it!



#3 Airhead

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Posted 15 March 2013 - 16:03

Once you feel light on the skids, it is a good instinct to not raise anymore collective until all lateral and longitudinal motion is stopped. If something seems wrong, stop. Raise until light, when motion is noticed lower slightly, adjust cyclic, raise a little, and do that sequence until all the force is vertical. The right yaw you developed is from the power being increased so as power is pulled some left pedal is needed to balance the torque.

In your situation, i.e. muddy and one of your first solo flights, take it really really slow. It is easy to get some backward motion as the front lifts first so the cyclic must be moved forward as collective is increased. Same technique as a slope.

At the first sign of trouble, do not raise anymore collective, instead slightly lower. It may seem like pulling in more collective will get you out of the situation by getting away from the ground but you won't roll if the power isn't there.

Pulling more power to get unstuck is the worst thing you can do. When light on the skids, try gently wiggling the skids with the pedals. This may break the suction. Also your instructor should have been thinking about this muddy situation, maybe they need to put down some rubber matting or wood and carpet. Some kind of platform to set down on and keep those robbies from getting stuck and crashing.
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#4 Spike

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Posted 15 March 2013 - 17:21

With muddy surfaces, when in doubt, apply slight fore and aft cyclic inputs as you slowly raise the collective. Typically, you should know where the approximate cyclic center-point is for a pick-up. Simply rock the machine up and you should feel it breaking free at the appropriate power setting(s). However, if it doesn’t break free, then you know you’re in too deep…. Stop and reassess….
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#5 Goldy

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Posted 16 March 2013 - 13:57

I assume this was your first or second time solo trying to lift off? Of course, your instructor should have told you that the R22 will lift nose high and you will need a lot of left lateral to offset the lack of weight in that seat. When solo, I start with a significant amount of left lateral cyclic input, then start lifting with the collective slowly, as the nose comes up, just let it come up slowly and then gently push it forward.

It flies like a different beast solo than with an instructor, but NEVER allow yourself to raise collective, even a bit, when stuck to the ground. The Dynamic rollover will happen quicker than you can possibly react to. Using the pedals will move the nose around and help unstick you from the ground if needed.

I did the same thing early on landing in mud solo, and the results were the same....I jerked it up and was lucky I didn't roll it over....classic poor technique.

Good to talk about it for the guys/gals that are out there pre-solo learning..
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#6 Heli1223

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Posted 16 March 2013 - 19:42

Once you feel light on the skids, it is a good instinct to not raise anymore collective until all lateral and longitudinal motion is stopped. If something seems wrong, stop. Raise until light, when motion is noticed lower slightly, adjust cyclic, raise a little, and do that sequence until all the force is vertical. The right yaw you developed is from the power being increased so as power is pulled some left pedal is needed to balance the torque.

In your situation, i.e. muddy and one of your first solo flights, take it really really slow. It is easy to get some backward motion as the front lifts first so the cyclic must be moved forward as collective is increased. Same technique as a slope.

At the first sign of trouble, do not raise anymore collective, instead slightly lower. It may seem like pulling in more collective will get you out of the situation by getting away from the ground but you won't roll if the power isn't there.

Pulling more power to get unstuck is the worst thing you can do. When light on the skids, try gently wiggling the skids with the pedals. This may break the suction. Also your instructor should have been thinking about this muddy situation, maybe they need to put down some rubber matting or wood and carpet. Some kind of platform to set down on and keep those robbies from getting stuck and crashing.


That is absolutely right, I couldn't have said it better!

However, I think I caused a misconception here. Allow me to rephrase: The surface was clay, but NOT muddy...that would be stupid to put a 'solo consolidation student' onto such a surface at all, I agree. The surface was clay like I said, and what happened was the helicopter lifted in the front and drifted backwards, thus digging the back of the skids (the sharp edges) into the 'softer than normal clay'...

Yes, the main reason the helicopter yawed to the right was because of the extra power being added, I forgot that part (probably this was the main reason) however I don't think it can be disregarded that the yawing was helped along by the stuck left skid and 'suddenly unstuck' right skid.

The 'slope technique' is the best, I agree. Practicing slopes by wheelying on the skids is probably the safest way to get the technique right before trying to do slopes. Using collective to raise and lower the skid SMOOTHLY and NOT the cyclic is key in my view.

The way you described it makes perfect sense...and NEVER tense up lol. Thanks for the advice!

#7 Heli1223

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Posted 16 March 2013 - 19:55

Yeah. Never lift the collective when in doubt... Have a clear reason for doing it - there are no free tickets for getting in the air...it doesn't 'just work out'...You have to MAKE it work out...I learned that clearly enough though!
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#8 ridethisbike

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Posted 26 March 2013 - 20:03

Yeah. Never lift the collective when in doubt... Have a clear reason for doing it - there are no free tickets for getting in the air...it doesn't 'just work out'...You have to MAKE it work out...I learned that clearly enough though!

 

A saying comes to mind here... "Take offs are always optional. Landings are not."



#9 aeroscout

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Posted 26 March 2013 - 20:53

If you suspect your skids are in soft ground, or during winter in snow slush or ice, using anti torque pedal inputs can loosen the skids (or skid) from being stuck.


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#10 Heli1223

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Posted 27 March 2013 - 08:50

A saying comes to mind here... "Take offs are always optional. Landings are not."

Ridethisbike, I do not fully agree though...some landings are less desirable than some takeoffs, depending on the situation off course.
I do get your point that if your in the air you HAVE to land again, but I do not think this is so relevant here, because it was PERFECT conditions for flying and the surface was perfect (if you read my update to the first post where I rephrased a few things and in particular the surface condition).

Peace!



#11 ridethisbike

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Posted 27 March 2013 - 17:36

Ridethisbike, I do not fully agree though...some landings are less desirable than some takeoffs, depending on the situation off course.
I do get your point that if your in the air you HAVE to land again, but I do not think this is so relevant here, because it was PERFECT conditions for flying and the surface was perfect (if you read my update to the first post where I rephrased a few things and in particular the surface condition).

Peace!

 

I think you missed the point. You said in the post I quoted above that you should "Have a clear reason for doing it" (lifting the collective). Meaning you have the OPTION of aborting that lift off.

 

The saying I quoted has nothing to do with weather, only that if something doesn't feel right before you get off the ground, you always have the option to stay on the ground.


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#12 SBuzzkill

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Posted 29 March 2013 - 19:35

I'm a very low time guy, but I try to be as deliberate as I can with my flying.  If something doesn't feel right I pause and let my brain catch up with what I'm going.  I see a lot of guys react to a sloppy pick up by yanking the helicopter into the air, or a bad set down by dumping collective and planting it.  I hate doing that.

 

Thanks for sharing with us.  When you can admit you did something wrong and share it then it's something you can learn from, and you are adding chapters to your book of experience.


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#13 HoveringHelicopter

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Posted 22 December 2013 - 09:28

Wow!  Good Story and a great reason to always be thinking 'what if'!







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