Robinson R22 Low Rotor RPM

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Tony Carmody
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Robinson R22 Low Rotor RPM

Postby Tony Carmody » Sun May 17 2015, 09:42

I noticed in volume 04/issue 04/May 2015 of the Aviation Trader Air Waves that there is a possibility that a newbie might misunderstand advice given on page 10 in the article - "What Goes Around" and as a result get into serious if not deadly strife.

The article talks about Low Rotor RPM in general but seems to have a Robinson R22 theme entwined as the R22 is mentioned a number of times.

The advice may be fine for some helicopters:

"Recovery from low rotor rpm is a matter of:
A. Lowering the collective to reduce the rotor blade angle of attack
B. Adding engine power"

But it is in the wrong order for an R22.

As soon as you lower the collective in the R22, besides allowing the nose to drop, the mechanical connection between the collective and the carb butterfly valve shuts the butterfly valve which in turn could dramatically reduce the available engine power and in some cases make recovery from a Low Rotor RPM situation very difficult.

So.... if you encounter a Low Rotor RPM scenario on a R22:

A. lead by winding the throttle wide open to keep the carb butterfly valve wide open while -
B. simultaneously lowering the collective as required
C. load the rotor disc if possible with aft or even lateral cyclic in that order

Hope this helps clear this one up as on a trip to WA recently I spoke to a number of experienced Robinson pilots and hardly anyone knew the correct procedure or how the Robinson throttle system worked.

Another interesting discussion on the way: if you have a drive belt failure - don't try and fly the R22 to anywhere but the immediate area in front of or along side you - with the collective full down.
Trying to make a spot just that little bit further away with the collective off the floor can very quickly result in a loss of Rotor RPM which in turn makes the helicopter turn into the proverbial brick.
I'd rather take my chances with a controlled crash than the brick scenario.

Tc :)
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Heli Bloke
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Re: Robinson R22 Low Rotor RPM

Postby Heli Bloke » Sun May 17 2015, 10:08

Gday Tony,

I'll bite... I don't understand why someone would not turn completely about face or raise lever to increase range in all circumstances (as you imply) post belt failure in an R22. It sounds interesting... would you mind explaining?
headcase
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Re: Robinson R22 Low Rotor RPM

Postby headcase » Sun May 17 2015, 10:29

Roll on throttle and then "lower to live".
ChicoCheco
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Re: Robinson R22 Low Rotor RPM

Postby ChicoCheco » Sun May 17 2015, 19:13

He may refer to that case of drive belts 'jamming' the upper sheave/pulley. I can't recall details/report.

If simply losing drive with engine running, it'd likely overspeed without load suddenly. If nothing's broken besides belts, why would max range auto be an issue, subject to having sufficient height AGL before bringing the RRPM up again last few hundred feet?
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AHIA
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Re: Robinson R22 Low Rotor RPM

Postby AHIA » Sun May 17 2015, 22:19

Tony,

Good call re article. I have arranged for Airwaves to publish an update on various forms of rotor stall in next edition. This will clear up this up this very important matter you have raised. Almost a year ago the AHIA send a lengthy correction to CASA re the Part 61 MoS; which then was probably written by an aeroplane person; especially in the low flying emergencies. All about "G" meter limits, etc.

Not sure where it has all gone to date as CASA has been overwhelmed by complaints about the MoS; (much appears to have been lost?); many versions have passed under the bridge and more are planned; especially as the AHIA has made many face to face meetings with the new DAS and Truss. Tomorrow 19 May '15 - we commence a more formal link up via teleconf to start yet again working up the pile of 61 wreckage and attempt to bend things back into shape.

As an aside did you see the DAS's recent comment that the regulatory review may run 2 to 4 years? Look what happed to the engineers and Part 145 recently tossed out of parliament. That took forever to sort out and maybe the engineers are still not happy.

If you need a copy of the coming article - we can send a freebie - secretary@austhia.com. Just send your email.

AHIA - Secretary

Urgent reminder - DAS has written to every pilot asking them what holes need fixing with Part 61. This is your chance to go to CASA website and tell them what you think! Do it now and if you don't - then your grumbling will be pointless when it all becomes the final legislation!!!
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Re: Robinson R22 Low Rotor RPM

Postby actionman » Mon May 18 2015, 06:31

Yep, I was very disappointed when I read a recent Airwaves section of the trader where a CASA FOI who is supposed to be an authority on such things completely dropped the ball on the recovery of low RRPM in an R22. And even now when I talk to robbi pilots about it and they say, yep roll on the throttle and lower the collective, but most of them didn’t know you must roll it on fully to disable the correlator.
So remember, low rrpm in flight, don’t just roll it on, roll it on fully til it hits the stop. There is no correlator at full throttle.
To all you examiners make sure your HFR candidates know this..
Cheers
That’s Life..
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CYHeli
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Re: Robinson R22 Low Rotor RPM

Postby CYHeli » Mon May 18 2015, 06:47

And this is precisely why the R22&44 are subject to the SFAR73 and why CASA has made them subject to a specific flight review. At least one now covers the other.
What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others.
County
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Re: Robinson R22 Low Rotor RPM

Postby County » Mon May 18 2015, 11:09

With regard to responding to "the Letter" it would have been good to see or know the following
My Letter dated 30/5/15 was received mid week, can anyone tell what changes have been made with regard to this...
Some of the changes already made relate to check pilots conducting proficiency checks, low level rating and aerial mustering training and flight testing, fire fighting operations, aerial application proficiency checks and R22 and R44.
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CYHeli
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Re: Robinson R22 Low Rotor RPM

Postby CYHeli » Mon May 18 2015, 22:59

Good question County.
I have asked for a summary of expected changes so that we don't waste our time (and theirs) listing stuff that is already accepted.

Unfortunately CASA appears to be too busy making the changes to let us know what they will be.
What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others.
County
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Re: Robinson R22 Low Rotor RPM

Postby County » Tue May 19 2015, 03:51

I heard a comment today that I think is most relevant here,
"We are being regulated into a state of parrillisis"

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