Dynamic Rollover video in Rotorway

[heliboy999]

Found this one today.

Apologies if already posted.

aMxTTZAHcFc&NR


HB999

[Flash0710]

from an armchair point of view, perhaps the frequencies were not matched......?

http://i10.photobucket.com/albums/a109/Noblelordflash/control-unit.jpg

hugs

xxx

f

[krypton_john]

It amazes me that this continues to happen. Surely it's absolutely basic, fundamental training to deal with onset of DR?

[RVDT]

It would probably amaze you when it happened to you also.

I know someone who built one of these and was cautioned that he should take some instruction in it before flying it.

He only had about 10,000 hours in helicopters at the time. He said "the guy was right" I probably would have tipped it over.

Your neck of the woods too KJ.

[ADRidge]

What I want to know is what was going on with the engine? It sounds like the RPM's were decreasing the entire time. I'm not trying to monday-morning quarterback the situation (but maybe I'm doing it anyway?) but if I'm flying something and the RPM's keep dropping like it sounded like they were, I'd have probably set it down a tad quicker.

Then again, maybe that wasn't the best spot for a test flight, assuming it was newly built. If it wasn't, and anyone knows the details, I will eat my words gladly. Heck, I'm just glad the fellow ONLY lost his ship in this one. I know what it feels like to be in denial of the situation at hand.

[VeeAny]

http://www.aaib.gov.uk/cms_resources.cfm?file=/Rotorway%20Executive%20162F,%20G-ESUS%2009-09.pdf

[krypton_john]

RVDT, I have heard it said many times about the RW, that transition instruction is more important in this type than just about any other, particularly with regard to DRO.

The pilot in the video attempted to correct out the roll-over, instead of dumping the collective which probably would have saved the ship.

Either pure lack of type training or poor skill.

[Edit] - I just watched it again with the sound on - sounded like the rpm started audibly dropping well before he got into trouble.

[VfrpilotPB/2]

Seems like lack of ability in overall charge of that RW, the correction almost works buy sadly we all see the result!

Peter R-B

[parasite drag]

How refreshing...as yet nobody's slagged the type !

"poor skill"

"lack of ability in overall charge of that RW"

'Nuff said.......

[heliboy999]

Dynamic rollover can be achieved in any helicopter and the correcting action is pretty much the same in any helicopter. Its always a shame to see a machine damaged whatever the type but its a nice video to demonstrate the situation and how easy it can occur and also how quickly.

[FH1100 Pilot]

Sad to watch, given the reported experience of the driver. But verrrrrry eentereshting!

The Rotorway's rotor(way!) turns the same direction as a Squirrel, opposite that of a Bell. So the nose will tend to want to turn to the left, requiring a bootful of right-pedal to keep it straight. In watching the video, you can hear the main rotor rpm clearly decreasing - and with it, the T/R rpm. The pilot appears to be focusing on...something else...and *probably* doesn't realize that he's just about out of right pedal.* The right skid touches and then the yaw rate begins. From our vantage point, it's easy to see what's coming. And it does.

Classic case of DR.

Man, I can so put myself in his shoes. "I know how to hover a friggin' helicopter, I can hover this thing."I can hear myself saying it. And Fate laughs and says, "Oh yeah? I'm gonna re-teach you something you may have forgotten about low tail rotor authority and decreasing t/r rpm, and how easy helicopters are to crash."

Ouch.




*Or, maybe he's just not aggressive enough with the right pedal. Just before it rolls over, you can see a little twitch of the nose to the right. So it mad me wonder: Did he have some pedal available that he wasn't using? In any case, he seems very rough on the cyclic. Or was it just a very gusty day?

[VeeAny]

FH1100

Just to answer the gusty day question and nothing more.

METAR EGSS 201350Z 36006KT 300V050 CAVOK 16/08 Q1027
METAR EGSS 201420Z 01005KT 320V080 CAVOK 16/07 Q1027
METAR EGSS 201450Z 34004KT 300V030 CAVOK 16/07 Q1027
METAR EGSS 201520Z 02005KT 310V050 9999 FEW040 17/07 Q1026

From Stansted a few miles away.

[chopjock]

Looks to me like the pilot lost RRPM because was not used to flying without a governor perhaps?
I speculate that pilot lifts into the hover, rpm starts to decay, so raises the lever, which decays rrpm even more and so raises the lever even more and so on.
Classic over pitching due to lack of manual throttle management. This easily occurs when learning, say in an R22 with the governor on, then flying another type with no governor or corellator.
Corrective action should have been to twist in more throttle and lower lever to recover RRPM.

[Whirlygig]

Have any of you read the report?


Commander’s Licence: Private Pilot’s Licence (FAA)
Commander’s Age: 74 years
Commander’s Flying Experience: 195 hours (of which 195 were on type)
Last 90 days - 10 hours
Last 28 days - 3 hours

All the pilot's hours were on type so I'm guessing he was used to lack of governor. I'd also hint that the pilot didn't need any transition training.

Wind also quoted as less than 5 kts.

Cheers

Whirls

[rotorboater]

Can you learn on a rotorway in the US?

[SilsoeSid]

krypton_johnThe pilot in the video attempted to correct out the roll-over, instead of dumping the collective which probably would have saved the ship.

Either pure lack of type training or poor skill.

dump (dump)
Transitive verb
To throw down or out roughly; empty out or unload as in a heap or mass

By 'dumping the collective lever'...do you not mean, 'lower the collective smoothly'?

Surely 'dumping' the lever would very possibly cause the aircraft to bounce on the other skid and roll in the other direction. (Not forgetting the potential risk of ground resonance)

[krypton_john]

Sid, your wording is much better!

[Nubian]

(Not forgetting the potential risk of ground resonance) Let uss know when you manage to get ground-ressonance with a semi-rigid rotorsystem....

[BHenderson]

Surely dumping the collective will have a higher success rate? As I recall, the 'tip over angle' is smaller for a loaded disc (because the lift acts through a point higher than the CofG), and therefore means that it will never tip over in the other direction with the collective lowered. Especially so, when you consider the damping effect of the landing gear. It would seem to me that the quicker you lower the collective the better chance you have. I've also considered the option of yawing into the roll, but I think if it got to that stage it would be too late anyway.

[ADRidge]

Consider my words eaten.

[SilsoeSid]

Let uss know when you manage to get ground-ressonance with a semi-rigid rotorsystem....

Sorry nubian,
All I know about a Rotorway can be written on a postage stamp no bigger than the space needed to write 'Rotorway'.

[SilsoeSid]

nubian,

According to the AAIB report http://www.aaib.gov.uk/cms_resources.cfm?file=/Rotorway%20Executive%20162F,%20G-ESUS%2009-09.pdf the aircraft in the video is a Rotorway Executive 162F

Please explain to me with my postage stamp knowledge, why in the CAA Check Flight Schedule for the Rotorway Exec, Exec 90 and 162F helicopters, does it say;

On touch down, check that there is no tendency for ground resonance or lateral padding and the landing gear functions satisfactorily.

http://www.caa.co.uk/docs/1455/SRG_FLT_CFS_241_Issue%202_16102006.pdf


Just need to know if I should pop down to the post office for a bigger stamp.

[ShyTorque]

"Ground resonance" is an undamped vibration of increasing amplitude. I was of the understanding that a semi-rigid rotor system (or any other) was not immune, but perhaps less prone.

[griffothefog]

I hope I can still take to the skies at 74 years young..... I'll remember to take my shoe horn with me..... Pardon??? :{

[Nubian]

SilsoeSid,

As to your question about why the UK CAA have the sentence written in their check-forms, I must answer with a question; What is "lateral padding"?? This is a term I have never come across before.
It is followed up with "the landing gear functions satisfactorily". I would assume that the function should be: "keeping the helicopter fuselage a foot or 2 safely off the ground". After all this is a small helicopter with skids, not with hyd. operated retractable gear.
I have been asked once by a CAA-representative on an audit, how we would go by to change the tyres of our helicopter (when the gentleman did not see a jack in our hangar) when I replied friendly that I would take the ground-handling wheels to a tyreshop and have it done there, as we were operating 206B's and L's....

So, the note on the checkform, could maybe be along those lines..

I'm not sure if it fits your stamp, but I went back to my old Helicopter-books to confirm that I had forgot my aerodynamic knowledge.

The vibration you get in GR, is when you get an offset center of mass in the main-rotor. This has a few causes, but mainly due to lead-lag dampers in the head being weak in combinations with shocks from the landing gear (skids or wheels). usually due to; main-gear dampers being faulty, incorrect tyrepressure, hard landings, slope-landings (partial landing, loading pax from steep slope etc.)

From "Basic Helicopter Handbook": In general, if groung resonace occurs, it will occur only in helicopters possesing three-bladed, fully articulated rotor systems and landing wheels. (however, the term here should be undercarrige, as it also involves skidded helicopters)

From "Principles of Helicopter flight": Rotors that have substantial in-plane stiffness and that are not fitted with lead-lag (drag) hinges, or their equivalents, are not susceptible to ground resonance and so require less damping in the rotor head or undercarrige"

Have had a few onset encounters over the years in diffrent machines, all being 3 bladed rotorsystems, skidded gear. In which MR or landing-gear dampers have been replaced shortly after.

[SilsoeSid]

Nubian,

Lateral padding, as I understand it would be the aircraft rocking lightly from skid to skid. Incipient GR?

Demonstrated classically in a Gazelle with the nose up slope, light on the skids and just about on the stops.

From "Basic Helicopter Handbook": In general, if groung resonace occurs, it will occur only in helicopters possesing three-bladed, fully articulated rotor systems and landing wheels. (however, the term here should be undercarrige, as it also involves skidded helicopters)

Mmm, I believe the first BO105 was destroyed on the ground due to Ground resonance, mind you it was with a Scout MR head. Last time I was in one they had 4 blades.

[SilsoeSid]

Nubian
it will occur only in helicopters possesing three-bladed.....,

UK Military Aircraft Losses (http://www.ukserials.com/losses-1990.htm)

07/12/1990 XR519 WC Wessex HC2
Written off in a ground resonance incident at Shawbury, Shropshire due to a faulty hydraulic component in the lead-lag damper (rotor head).

The airframe was disposed of for scrap Ground resonance occurs when the rotors move out of synchronisation due to a fault, as above or due to a heavy landing or sudden control movement. This causes the centre of gravity to move outwards and if not controlled, the helicopter will begin to rock and very quickly shake itself to pieces

[newfieboy]

Quote:
Let uss know when you manage to get ground-ressonance with a semi-rigid rotorsystem


Although the AS350 is three bladed system and has a little lead and lag, through the elastomeric bearings, ( or as my engineer calls them Lamanated thrust bearings) it is offially classed as a semi-rigid system, and you can definately get ground resonance in it

Suprising what you look up while sitting in an exploration camp waiting for freezing fog to lift, ha ha.:ugh:

[SilsoeSid]

http://www.ntsb.gov/ntsb/GenPDF.asp?id=DFW06LA057&rpt=fi

Agusta / A109E N142CF
The National Transportation Safety Board determines the probable cause(s) of this accident as follows.
The pilot's inadvertent encounter with ground resonance which resulted in the destruction of the helicopter.

[ShyTorque]

Three blades only? No. The number of blades has little to do with it. I know of at least two (four bladed) Wessex that ended up on their sides. The word on the block was two seconds from beginning to helicopter on it's side.

If any rotor system goes out of balance for any reason, and lateral padding begins, the undercarriage, by design, wheels or skids, should damp it out. If it doesn't, and the amplitude increases, it's possible for the aircraft to rock very violently until something major happens.

[Gaseous]

True ground resonance occurs when the frequency of a vibration within the main rotor system is the same as the resonant frequency of the landing gear. The rotor feeds energy into the resonating system and produces a very large amplitude vibration. It is usually suppressed by dampers within the landing gear which lower the resonant frequency to prevent resonance at frequencies which would be damaging. I cant recall if lead-lag dampers help suppress ground resonance - edit - They do by helping suppress lateral out of balance vibration which could set up resonance if there is a problem with the landing gear damping. 2 bladers are not prone hence no skid dampers.

Lateral padding occurs due to tracking errors in the main rotor system which result in vertical bounce. There is also - usually - a horizontal component to the tracking error which when very light on the skids, or just about hovering, will cause the skids to alternately lift and lower, hammering the ground. It only happens at flying rpm with significant pitch applied. Number of blades irrelevant. Not the same as rocking caused by simple imbalance in the main rotor.

Ground resonance can occur at any RPM with or without pitch applied.

Neither feel nice.

[Nubian]

SilsoeSid,

As for my previous post focusing on 3 blades, it should have been multibladed.
Sorry for misleading focus.

No question about you get it in the Gazelle, similar type rotor.

With regards to the Bo-105, with the Scout head, well what can I say other than, similar type rotor. Allthough 4 bladed, it has dampers, which is the clue here. Haven't heard of incidents in the 105 with the current Rigid head.... (no dampers)

With dampers in the head, you will have the posibility for the Center of mass to be displaced and causing the imbalance that will ultimately destroy the helicopter if not corrected for.

Newfiboy,

Yes, the 350 can get it as well, as it has a type of Lead-lag damper. As long as you can get more/less degrees between the diffrent rotorblades than what it should have, you will displace the Center of Mass from what should be centered equally around the mast.
Therefore you'll need more than 2 blades that are not rigidly connected, to do so.

[MightyGem]

For those who haven't seen it:

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...and from the side:

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[jim63]

Was this operator error,lack of skill or ???
aMxTTZAHcFc

[HillerBee]

Well the skills of the pilot, don't impress me. It also seems he's setting it down by reducing power and accordingly rotor rpm. Obviously the place he tried to set it down wasn't the right one and there was movement in all directions, what caused the dynamic roll-over was the sideways movement.

[jim63]

Here is another pilot I guess that is showing off.Looks like he even has passengers.I would guess that he bent the skids or did some kind of damage to it.
gd5lHgsX7LQ

[flap flap flap]

A rotorway accident not caused by a mechanical defect. Must be a first!

[elro]

The Rotorway accident was already discussed please refere to: http://www.pprune.org/rotorheads/402789-dynamic-rollover-video-rotorway.html
And to put it into layman's terms 'yes' all he had to do was drop the collective.

[TRC]

I would guess that he bent the skids or did some kind of damage to it.


I would expect the fuselage skin to be wrinkled just behind the honeycomb roof panel - if not the tailboom as well.

That pilot should be quietly led away and re-trained as a bulldozer driver.

[lelebebbel]

several hundred thousand euros worth of damage on the 206 in that video. The pilot became known as "touch-and-go-joe" - as far as I know, he is still flying.

[-272.15 degrees Cels]

Removed due to threads being merged.

[Arnie Madsen]

Regarding the Rotorway rollover video:

When you consider this guy is flying a helicopter that he built himself in his own garage we have to recognize a significant accomplishment. Many of us "professionals" without a scratch on our records are not qualified to change an oil filter let alone build the complete machine we are flying in.

We can fault this rookie pilot with not enough training or experience trying to solo but take a look at our "professionally trained" students in the industry and you will find plenty of crack-ups there too.

I do not know this Rotorway owner personally , but for all we know he has rebuilt his machine and and is flying right now as we type to each other about how smart we are.

I find it a fascinating concept that in some parts of the world a man can actually build his own helicopter in his own garage and go flying without being crushed under the thumb of a King or a Queen or a lord or a landlord or a baron or a thousand regulators who only know how to type regulations to keep people on the ground .

Practically every one of our aviation pioneers and inventers started out as home builders and most cracked up the first prototypes. Even our beloved Frank R. started out on his kitchen table before his wife kicked him out to the garage. :) Even his first prototype had to be fished out of the ocean but the pilot survived.

Even in modern day we have homebuilders who have designed, built, and flown an ultralight helicopter that weighes less than 254 pounds. It can do full down hovering auto's from 30 feet . Hundreds are flying for hundreds of hours with no mechanical issues.

Like I said , notwithstanding rookie pilot errors , I still find the home built concept an amazing category and I hope it never gets regulated to death.

With modern day networking and the internet , these plumbers, and carpenters and farmers work closely together on their homebuilts and share endless safety tips and concerns. Our beloved CAA and FAA work at the speed of molasses by comparison.

Three cheers for the homebuilder who has the freedom to kill himself in as many ways as possible if he is not careful.

Heck , I know a literal homebuilder (a guy that built his own house) who died when he flew off the roof because the wind caught the sheet plywood he was carrying. The regulators are still trying to figure out if it was a carpenter error or a flying error. :)

Best regards to all the folks who value freedom.
Arnie Madsen