Robinson R22 Corner [Archive copy]
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R-22 Nr Governor
A discussion ensued this weekend about the R-22's Nr governor.
Specifically, we know that if you were at, say, idling above the tail resonance range and it was on, one could bring up the throttle slightly and at some point the governor would "grab it" and bring you on up to 104% No issue there.
Does the governor have a "high Nr limit" above which point it would fail to function?
In other words, if one found themselves in an overspeed condition above 104%, and the governor was off, would it then take Nr back down when engaged, or is there a speed at which it no longer could do that?
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Marc
Specifically, we know that if you were at, say, idling above the tail resonance range and it was on, one could bring up the throttle slightly and at some point the governor would "grab it" and bring you on up to 104% No issue there.
Does the governor have a "high Nr limit" above which point it would fail to function?
In other words, if one found themselves in an overspeed condition above 104%, and the governor was off, would it then take Nr back down when engaged, or is there a speed at which it no longer could do that?
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Marc
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RW
I believe the governor should work at all engine speeds above the normal 80% but can't find the info in R22 POH. On the other hand, there shouldn't be any occasion when the engine should be overspeeding with no governor in use, unless there is a bad pilot at the controls or this is a hypothetical situation.
I look forward to the correct info.
I believe the governor should work at all engine speeds above the normal 80% but can't find the info in R22 POH. On the other hand, there shouldn't be any occasion when the engine should be overspeeding with no governor in use, unless there is a bad pilot at the controls or this is a hypothetical situation.
I look forward to the correct info.
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The highest overspeed I have had while flight training has been 115%. The governor was trying to fix the error but I was also taking control so not sure how fast it would have fixed the problem, I didn't feel compelled to wait and find out.
As said, best to keep out of that area all together!
Fly safe...
As said, best to keep out of that area all together!
Fly safe...
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True, no one wants to be there in the first place 
It is a hypothetical. I'm sure we all covered malfunctioning governors commanding an overspeed, this is somewhat reverse to that.
The info is appreciated, I wasn't able to find anything in the POH either.
Thanks!
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Marc
It is a hypothetical. I'm sure we all covered malfunctioning governors commanding an overspeed, this is somewhat reverse to that.The info is appreciated, I wasn't able to find anything in the POH either.
Thanks!
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Marc
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If the governor were off and the Nr was in excess of 104% and then it was turned on, the detection system would signal the gearmotor to simultaneously decrease throttle and increase collective reducing the rotor speed to the deadband range of 101% and 104%. Conversely it would do the opposite if the system were below 101% and the governor was turned on.
I do not know if there is a speed at which the governor would not respond.
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The Cat
I do not know if there is a speed at which the governor would not respond.
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The Cat
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this is sort of related, but not really: the r22 rpm needles will stick at the upper limit, if subjected to a large enough overspeed; so what if you have an engine failure and in the heat of the moment, overspeed the rotor? there would be no remaining tach to land, as far as I can figure - any thoughts?
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as far as i can see nobody has mentioned that the lower limit is 80% at which the governor will grab it, also I am not sure at what point it fails to work on the upper limit, but i believe it to be 110-115%,
I did hear a story of someone who overspeed one for about 2 minutes, but they were above the governor range and it didnt respond and unforunately they didnt have the presence of mind to roll the throttle at all and presumably have done some damage. (imagine what damage they could do starting a jetranger up!!!!)
also there was an accident recently where the tail fell off an R22 as a direct result of an overspeed, because as I understand it the tail rotor drive shaft starts "whipping" at about 130-135% because the harmonics and resonation have been designed out of the normal operating range and this whipping causes a lot of collateral damage, so that would efectively be your upper upper limit if you had a real engine failure and mentally you completely lost the plot during the subsequent auto and engine off landing.
a semi related issue, I have noticed that there appears to be a lot of resonation in the R44 at 75% rpm when running up, but am not sure where this is coming from, does anyone know?
elpirata
I did hear a story of someone who overspeed one for about 2 minutes, but they were above the governor range and it didnt respond and unforunately they didnt have the presence of mind to roll the throttle at all and presumably have done some damage. (imagine what damage they could do starting a jetranger up!!!!)
also there was an accident recently where the tail fell off an R22 as a direct result of an overspeed, because as I understand it the tail rotor drive shaft starts "whipping" at about 130-135% because the harmonics and resonation have been designed out of the normal operating range and this whipping causes a lot of collateral damage, so that would efectively be your upper upper limit if you had a real engine failure and mentally you completely lost the plot during the subsequent auto and engine off landing.
a semi related issue, I have noticed that there appears to be a lot of resonation in the R44 at 75% rpm when running up, but am not sure where this is coming from, does anyone know?
elpirata
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elpirata, I did mention the governor taking over at 80% but maybe didn't word it the way I should have.
As for the other point made above about no needles to indicate rpm after an overspeed (ie stuck), answer this question: does the low rpm horn work mechanically from the needles?
As for the other point made above about no needles to indicate rpm after an overspeed (ie stuck), answer this question: does the low rpm horn work mechanically from the needles?
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Intersting question on the overspeed. I agree with LZ on what would happen if the governor were switched on during overspeed with govnr out initially. It has the ability to add and remove throttle input and is constantly doing so, eg. when flaring, when a gust of incoming airflow enters the disc, when the pilot uses right pedal in the hover etc. It would react just the same in the above conditions.
I'm not so convinced that it will raise the lever slightly to control excess RRPM as I understood the latest (Mk 3) gvnr did not move the lever like the Mk 2 model used to (lots !)but I'd be corrected.
An intersting point is that if the governor can only increase and reduce throttle input, it is only controlling RRPM through that. It doesn't have any mechanism (a brake or similar) to slow RRPM if they were increased above the range of governor/throttle control by an aerodynamic effect on the disc and I wonder that if some flying technique or manooeuvre caused a huge increase in RRPM it may be out of the governor's authority range and it would not be able to reduce RRPM.(If it does still increase collective pitch by rasing the lever then the increase in drag would reduce RRPM). So, in theory at least, the upper limit of governor operation has to be when the governor can no longer reduce RRPM by reducing throttle.
Incidentally, I had an R22 governor fail a few years ago which allowed RRPM to rise to around 110% in straight and level flight before it was switched out. The fault was traced to a faulty logic unit/signal generator which is fitted behind the LHS back, on the cockpit side of the firewall.
One of the main concerns (and there are many)
about overspeed is the amount of centrifugal force exerted on the MR blade attachment bearings ('spindle bearings')is 4.5 tons at 104% but will rise exponentially to 9 tons if allowed to reach 114%.
I'll find out about the horn operation in the morning, interesting Q! I'm pretty certain it is a system that blows the horn if impulse rate from the left mag becomes too low, as opposed to being triggered by the needle, but we'll see.
I'm not so convinced that it will raise the lever slightly to control excess RRPM as I understood the latest (Mk 3) gvnr did not move the lever like the Mk 2 model used to (lots !)but I'd be corrected.
An intersting point is that if the governor can only increase and reduce throttle input, it is only controlling RRPM through that. It doesn't have any mechanism (a brake or similar) to slow RRPM if they were increased above the range of governor/throttle control by an aerodynamic effect on the disc and I wonder that if some flying technique or manooeuvre caused a huge increase in RRPM it may be out of the governor's authority range and it would not be able to reduce RRPM.(If it does still increase collective pitch by rasing the lever then the increase in drag would reduce RRPM). So, in theory at least, the upper limit of governor operation has to be when the governor can no longer reduce RRPM by reducing throttle.
Incidentally, I had an R22 governor fail a few years ago which allowed RRPM to rise to around 110% in straight and level flight before it was switched out. The fault was traced to a faulty logic unit/signal generator which is fitted behind the LHS back, on the cockpit side of the firewall.
One of the main concerns (and there are many)
about overspeed is the amount of centrifugal force exerted on the MR blade attachment bearings ('spindle bearings')is 4.5 tons at 104% but will rise exponentially to 9 tons if allowed to reach 114%.
I'll find out about the horn operation in the morning, interesting Q! I'm pretty certain it is a system that blows the horn if impulse rate from the left mag becomes too low, as opposed to being triggered by the needle, but we'll see.
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Someone mentioned above that the old style of governors use to operate the collective as well. I remember it as having a brown snake under your had trying to wriggle its way out. The thing would move up and down and roll on and off continuously which was a very uncomfortable thing - it literaly made you let go of the collective. They changed it for the better. Now it only operates the throttle.
One thing that should be noted is that the governor sensing unit is in the magneto's. Not as you would think, as a result of RRPM. It is controlled by engine RPM only. If you lose the engine the governor is probably no longer needed (hee hee). It is up to the pilot to control an overspeed all by himself. There is no input for the governor to switch itself off at high engine RPM.
Cheers
One thing that should be noted is that the governor sensing unit is in the magneto's. Not as you would think, as a result of RRPM. It is controlled by engine RPM only. If you lose the engine the governor is probably no longer needed (hee hee). It is up to the pilot to control an overspeed all by himself. There is no input for the governor to switch itself off at high engine RPM.
Cheers
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So, in answer to the above about control of rotor rpm with stuck needles. If you were able to, with enough time to think, rotor rpm could be lowered slowly to the horn coming on and then controlled accordingly using the horn as a low limit. The possibility of overspeed at the bottom isn't really a problem if engine failure occurred, the main thing is to get to a safe height without losing rpm and without overspeeding, then saving your life as the first and most important thing. A helicopter can be fixed/replaced, a life cannot.
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So imagine this scenario. You are a low time R22 pilot, and you have lifted off and are climbing out and notice that both needles are off the clock and the governor is switched off (forget about how you got into this situation). You switch on the governor and to your dismay it fails to bring things back into the green band. You at first think the needles are stuck up there for some reason but the last thing you want to do is roll off the throttle in case the horn is u/s too and you inadvertently lose RRPM, as it has been drilled into you that danger lurks down there. However a blade centrifugal force of 9 tons lives above the top of those meters as noted above.
So what do you do?
So what do you do?
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Mine too Muffin ...
I would pull in a slight amount of collective and lower a crack of throttle, looking for a response, and if not getting any, return to departure point ASAP. (the arguement is that you are over, so a slight reduction if the indications are correct shall not harm you, but it leads me to -> )
At the same time, if it is a governor gauge malfunction, you might just be sitting where you should be and not seeing that indication.
So that begs my next question? Could one in that situation tell if the engine is truly "Revved" by ear? (Assuming you have some time in it, you should notice an "elevated" noise level (maybe?)
I suppose there could be numerous permutations of this, dependant on what one wants to try.
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Marc
I would pull in a slight amount of collective and lower a crack of throttle, looking for a response, and if not getting any, return to departure point ASAP. (the arguement is that you are over, so a slight reduction if the indications are correct shall not harm you, but it leads me to -> )
At the same time, if it is a governor gauge malfunction, you might just be sitting where you should be and not seeing that indication.
So that begs my next question? Could one in that situation tell if the engine is truly "Revved" by ear? (Assuming you have some time in it, you should notice an "elevated" noise level (maybe?)
I suppose there could be numerous permutations of this, dependant on what one wants to try.
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Marc
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Spot on Helimutt.
Part of my training was to fly with no tacho. (needles) visible and to manage RPM you did just that, reduced RPM very gently by raising the lever (remembering that there is a lag) and when you get a 'beep' lower it slightly. Have to say that RPM awareness without ref. to tachs is MUCH easier in 300's, even a two hour improver can hear the difference, much harder in R22 but not impossible.
I have to say that I totally agree with the view that the most important thing is for the student to get to a good height (10 ft or less) with low forward AS (it slides best foward!) and it is then unlikely that serious injuries will be sustained (as far as can be predicted) whatever pilot action follows (or not).
Too many low time pilots and students have the wits scared out of them by instructors (although they'll rarely admit it) demonstrating EOL after EOL like a kid with a new toy. They'll sometimes develop an aversion to the word "Autos" when most of them are terminated 'full on to the ground'. (Oh god, not again....!) Too much focus appears to be placed on engine failure when it is far more likely that the student will get himself into vortex than to suffer this.
(Two accidents very recently in NZ may well have been due to vortex condtions but no engine 'failures' (more often poor carb heat management is the cause of stoppage anyway) appear to have occurred for a much longer period).
Sure, some EOL's should be done, and dual of course, but how many demonstrations of full vortex recovery are done during PPL? 1 or 2 maybe, (if any) reinforced by 5 or 6 from incipient stage? I say this because I beleive the number of both emergency procedures should be about equal and whilst there may be need for more vortex recoveries, less EOL's full on to the ground would bring much benefit -
Less stress on the Helis.
Perhaps less insurance (dream on...!)
Less risk of rollover and all the associated dangers of EOL.
Students much happier to enter auto, control RPM, choose agood site then get the most crucial part done well without fearing the ending and perhaps performing poorly throughout the approach because of that fear.
What's the point of embedding an aversion to a life saver?
The focus should be only centred on getting to that ideal height/speed right through training and one day, maybe during a future check ride it may be allowed to just slip onto the ground as easy as pie, no fuss or drama.
And yes, the Heli IS expendable over one's life and I think that less would be lost overall if 'full on' EOL demo. were rarer. Maybe more unlucky vicitims of engine stoppage would survive if they were taught with more attention paid to getting to less than 10 ft and almost zero AS.
Anyway, just my view.
Part of my training was to fly with no tacho. (needles) visible and to manage RPM you did just that, reduced RPM very gently by raising the lever (remembering that there is a lag) and when you get a 'beep' lower it slightly. Have to say that RPM awareness without ref. to tachs is MUCH easier in 300's, even a two hour improver can hear the difference, much harder in R22 but not impossible.
I have to say that I totally agree with the view that the most important thing is for the student to get to a good height (10 ft or less) with low forward AS (it slides best foward!) and it is then unlikely that serious injuries will be sustained (as far as can be predicted) whatever pilot action follows (or not).
Too many low time pilots and students have the wits scared out of them by instructors (although they'll rarely admit it) demonstrating EOL after EOL like a kid with a new toy. They'll sometimes develop an aversion to the word "Autos" when most of them are terminated 'full on to the ground'. (Oh god, not again....!) Too much focus appears to be placed on engine failure when it is far more likely that the student will get himself into vortex than to suffer this.
(Two accidents very recently in NZ may well have been due to vortex condtions but no engine 'failures' (more often poor carb heat management is the cause of stoppage anyway) appear to have occurred for a much longer period).
Sure, some EOL's should be done, and dual of course, but how many demonstrations of full vortex recovery are done during PPL? 1 or 2 maybe, (if any) reinforced by 5 or 6 from incipient stage? I say this because I beleive the number of both emergency procedures should be about equal and whilst there may be need for more vortex recoveries, less EOL's full on to the ground would bring much benefit -
Less stress on the Helis.
Perhaps less insurance (dream on...!)
Less risk of rollover and all the associated dangers of EOL.
Students much happier to enter auto, control RPM, choose agood site then get the most crucial part done well without fearing the ending and perhaps performing poorly throughout the approach because of that fear.
What's the point of embedding an aversion to a life saver?
The focus should be only centred on getting to that ideal height/speed right through training and one day, maybe during a future check ride it may be allowed to just slip onto the ground as easy as pie, no fuss or drama.
And yes, the Heli IS expendable over one's life and I think that less would be lost overall if 'full on' EOL demo. were rarer. Maybe more unlucky vicitims of engine stoppage would survive if they were taught with more attention paid to getting to less than 10 ft and almost zero AS.
Anyway, just my view.
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sps
My instructor had a few thousand hours in R22's and some of the things demonstrated to me were, looking back, unbelievable really.
I had an aversion to autos for the reason stated above. Every time he said "lets do some autos" I just wanted to go home.
I flew in the US for a spell and when I was doing my check flight with the instructor, I did the auto to the ground. He nearly s**t himself and informed me they didn't do them to the ground in training over there. I later found out he was a fixed wing instructor who had just converted to a rotary instructor and had 60 hours in helos!!!
Anyway, if I demonstrate an auto as an AFI I can only do them to a recover to the hover anyway. I personally don't see the point of going to the ground because the important part of an auto is an entry. If the student masters the initial entry, control all the way down, and knows the drill, then he has every chance of saving himself.
We all have our own ideas on this I guess.
I learned to fly using the R22 HP without a governor, and , having the lower tail, was great fun drawing lines on grass strips with the stinger!!!!!!
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"Practice Autorotation- Go, Oh S**T!!!"
My instructor had a few thousand hours in R22's and some of the things demonstrated to me were, looking back, unbelievable really.
I had an aversion to autos for the reason stated above. Every time he said "lets do some autos" I just wanted to go home.
I flew in the US for a spell and when I was doing my check flight with the instructor, I did the auto to the ground. He nearly s**t himself and informed me they didn't do them to the ground in training over there. I later found out he was a fixed wing instructor who had just converted to a rotary instructor and had 60 hours in helos!!!
Anyway, if I demonstrate an auto as an AFI I can only do them to a recover to the hover anyway. I personally don't see the point of going to the ground because the important part of an auto is an entry. If the student masters the initial entry, control all the way down, and knows the drill, then he has every chance of saving himself.
We all have our own ideas on this I guess.
I learned to fly using the R22 HP without a governor, and , having the lower tail, was great fun drawing lines on grass strips with the stinger!!!!!!
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"Practice Autorotation- Go, Oh S**T!!!"