Robinson R22 Corner [Archive copy]
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The way I've always done it in my R44 is, having completed mag checks to manually wind on throttle to test the RPM horn. The throttle is then shut to split the needles. I then turn on the governor and slowly wind on the throttle manually until 80% when the governor takes over and automatically takes it up to 102% (in the R44). This ensures that the governor is in control all the way so ensuring no overspeed and excercising the governor over its full range.
The Original Whirly
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Nr Fairy,
I'm trying to picture this scenario. At what point did you switch off the governor? Any idea how? The governor will not work at lower than 80% RPM, and has an upper limit of 115%, above which it won't kick in. If it's winding up the RPM, and gets switched off during that, does it go above 115%? I don't know, but I suppose it's possible. Also, if you raise the collective at all, that'll bring up the RPM too, if the governor's off.
If you go through the whole thing more precisely, I'll see if I can work it out.
I'm trying to picture this scenario. At what point did you switch off the governor? Any idea how? The governor will not work at lower than 80% RPM, and has an upper limit of 115%, above which it won't kick in. If it's winding up the RPM, and gets switched off during that, does it go above 115%? I don't know, but I suppose it's possible. Also, if you raise the collective at all, that'll bring up the RPM too, if the governor's off.
If you go through the whole thing more precisely, I'll see if I can work it out.
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NR,
Good on ya for seeking advice and not just flying off.
The 22 can handle amazing amounts of "rough" treatment. I guess having a big donk loafing about instead of ringing it's guts out helps.
Both needles "Off the scale" a wee bit hard to work out if the donk went to 111% or 130%. The ginger beers will have to make an assesment of possible damage.
Done something very similar years ago (overspeed on start H300). Got a pretty good idea how you're feeling
cheer up! in a 100yrs it won't matter at-all.
Personnally I teach manual throttle to 100% then gov on, wind throttle off a bit 95% to see it takes up the slack. Pick-up to the hover make sure gov keeps 104%.
Shut-down, manual throttle to 75%.....then gov off.
I don't like the way the gov "Cranks" on the throttle if you let it pick up from 80% (black box runaway springs to mind).
I've caught too many students trying to wind on throttle during shut down while fussing with the gov, so ensure they roll throttle off before thinking about anything else.
Ohh look, the suns come up. It must be another day
Good on ya for seeking advice and not just flying off.
The 22 can handle amazing amounts of "rough" treatment. I guess having a big donk loafing about instead of ringing it's guts out helps.
Both needles "Off the scale" a wee bit hard to work out if the donk went to 111% or 130%. The ginger beers will have to make an assesment of possible damage.
Done something very similar years ago (overspeed on start H300). Got a pretty good idea how you're feeling
cheer up! in a 100yrs it won't matter at-all.Personnally I teach manual throttle to 100% then gov on, wind throttle off a bit 95% to see it takes up the slack. Pick-up to the hover make sure gov keeps 104%.
Shut-down, manual throttle to 75%.....then gov off.
I don't like the way the gov "Cranks" on the throttle if you let it pick up from 80% (black box runaway springs to mind).
I've caught too many students trying to wind on throttle during shut down while fussing with the gov, so ensure they roll throttle off before thinking about anything else.
Ohh look, the suns come up. It must be another day
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Both needles off the clock? Am I right in thinking that the greater damage is likely to be to the engine, rather than the rotor?
I do my mag checks and needle splits at 80 per cent, then raise the lever a tad and flick the governor on. The governor takes the revs up and if all's well, the horn quits at 98 per cent. Anyone take issue with that?
Fairy: I've yet to do my overspeed. The suspense is killing me.
I do my mag checks and needle splits at 80 per cent, then raise the lever a tad and flick the governor on. The governor takes the revs up and if all's well, the horn quits at 98 per cent. Anyone take issue with that?
Fairy: I've yet to do my overspeed. The suspense is killing me.
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The Nr Fairy
Off the cuff I can think of three possibilities.
1) The governor failed. Wouldn't be the first time. It's a solid-state computer so it could easily be some spurious electrical fault that can't be duplicated during troubleshooting. See the safety bulletin about not flying close to transmission masts. I've had a governor that kept "hunting" for the right RPM, constantly surging by 1-2%. A new controller solved that.
2) Awfully unlucky timing if you bumped the governor switch off. If you keep your left hand on the throttle grip (as you should), you'll notice that with the technique that you describe (governor ON at 75%, roll up to 80%, governor takes over and puts RPM at the top of the green), the governor rolls the throttle off by a small amount as the RPM goes through about 97%. If you swith the governor off before this point an overspeed might result.
3) The governor got switched off with RPM at 104%, but then the collective creeped up (quite possible depending on rigging if the pilot doesn't hold it down). The mechanical correlator will then increase RPM quite a bit (nearly had an overspeed like that once).
If you let the governor bring the RPM up as you describe, it's a good idea to hold the throttle grip so as to prevent the governor from winding it open as far as it wants to. I hold it to keep the manifold pressure below 15" (near sea level). At low RPM the tail rotor is nearly useless, so on a slick or icy ramp the torque from an enthusiastic application of throttle by the governor (or pilot) can spin you around despite full left pedal.
t'aint natural
As I understand maintenance requirements following an overspeed: between 110% and 116% (over redline but still on the scale of the tach), simple inspection of both engine and rotor system, possibly also check tail rotor driveline runout. Over 116% (off the scale): expensive engine teardown inspection, several engine parts scrapped regardless, magnafluxing of several parts of the rotor system, main rotor spindle bearings inspected, and definitely check tail rotor driveline runout. Expensive and time-consuming.
Off the cuff I can think of three possibilities.
1) The governor failed. Wouldn't be the first time. It's a solid-state computer so it could easily be some spurious electrical fault that can't be duplicated during troubleshooting. See the safety bulletin about not flying close to transmission masts. I've had a governor that kept "hunting" for the right RPM, constantly surging by 1-2%. A new controller solved that.
2) Awfully unlucky timing if you bumped the governor switch off. If you keep your left hand on the throttle grip (as you should), you'll notice that with the technique that you describe (governor ON at 75%, roll up to 80%, governor takes over and puts RPM at the top of the green), the governor rolls the throttle off by a small amount as the RPM goes through about 97%. If you swith the governor off before this point an overspeed might result.
3) The governor got switched off with RPM at 104%, but then the collective creeped up (quite possible depending on rigging if the pilot doesn't hold it down). The mechanical correlator will then increase RPM quite a bit (nearly had an overspeed like that once).
If you let the governor bring the RPM up as you describe, it's a good idea to hold the throttle grip so as to prevent the governor from winding it open as far as it wants to. I hold it to keep the manifold pressure below 15" (near sea level). At low RPM the tail rotor is nearly useless, so on a slick or icy ramp the torque from an enthusiastic application of throttle by the governor (or pilot) can spin you around despite full left pedal.
t'aint natural
As I understand maintenance requirements following an overspeed: between 110% and 116% (over redline but still on the scale of the tach), simple inspection of both engine and rotor system, possibly also check tail rotor driveline runout. Over 116% (off the scale): expensive engine teardown inspection, several engine parts scrapped regardless, magnafluxing of several parts of the rotor system, main rotor spindle bearings inspected, and definitely check tail rotor driveline runout. Expensive and time-consuming.
Buitenzorg :
Your last paragraph has confirmed my worst fears. Ah well - like I say, at least no-one got hurt. I don't think it was governor failure, however much I'd like to !
Whirly :
Don't know where/when I switched the governor off. I THINK - and I don't know exactly, which is something else pissing me off - that I inadvertantly did it but don't know exactly when during the wind-up sequence. I didn't raise the lever - on that machine it was stiff enough to make me think I'd left friction on when I first lifted off, so it's not, in my mind, a possibility.
t'aint :
I do the mag checks at 75%, then wind up to 100%, lift the lever slightly and roll off to abut 95% - horn comes on at 97%, and I wind back up to 100% ( horn should go off ) then do the needle split, and as a natural consequence try to end back at 75% to do the final VAs. I'd done those when I got my brain-fart.
Hone :
When winding down, I simultaneously roll off throttle and switch off the governor after assuring with a brief glance the RPM is decreasing.
Thanks for all the input. However, can anyone describe to me how the thing is designed to work in the normal sequence of events, i.e. how FR thinks events should progress ?
Your last paragraph has confirmed my worst fears. Ah well - like I say, at least no-one got hurt. I don't think it was governor failure, however much I'd like to !
Whirly :
Don't know where/when I switched the governor off. I THINK - and I don't know exactly, which is something else pissing me off - that I inadvertantly did it but don't know exactly when during the wind-up sequence. I didn't raise the lever - on that machine it was stiff enough to make me think I'd left friction on when I first lifted off, so it's not, in my mind, a possibility.
t'aint :
I do the mag checks at 75%, then wind up to 100%, lift the lever slightly and roll off to abut 95% - horn comes on at 97%, and I wind back up to 100% ( horn should go off ) then do the needle split, and as a natural consequence try to end back at 75% to do the final VAs. I'd done those when I got my brain-fart.
Hone :
When winding down, I simultaneously roll off throttle and switch off the governor after assuring with a brief glance the RPM is decreasing.
Thanks for all the input. However, can anyone describe to me how the thing is designed to work in the normal sequence of events, i.e. how FR thinks events should progress ?
Iconoclast
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How high is up? How much is too much?
To: The Nr Fairy
According to the R-22 POH the maximum allowable rotor and engine speed is 104%. You indicated that you experienced an overspeed beyond that point however you did not indicate the actual rotational speed other than to state that the gages went off the scale. Any excedence of the allowable speed would necessitate some type of inspection, which you indicated was done. However if the overspeed drove the instruments off the scale there is no way of telling exactly how fast both the engine and rotor were turning. If this is the case, I would think that the helicopter should have been grounded and an engineering (not LAME engineering) examination should have been performed to determine if excessive stresses were experienced due to “Centrifugal forces" on the main and tail rotor blades and the two rotorheads as well as other rotating parts of the drive line. Also the engine should have been torn down to determine if any of the moving parts had been overstressed or possibly stretched.
Not knowing the CAA regs. I would think that there would be a requirement to enter the overspeed occurrence in the aircraft log with further indication of what inspections were performed to clear the helicopter for further flight. Otherwise your inadvertent overspeed may manifest itself at some later date causing harm to the unaware pilots.
According to the R-22 POH the maximum allowable rotor and engine speed is 104%. You indicated that you experienced an overspeed beyond that point however you did not indicate the actual rotational speed other than to state that the gages went off the scale. Any excedence of the allowable speed would necessitate some type of inspection, which you indicated was done. However if the overspeed drove the instruments off the scale there is no way of telling exactly how fast both the engine and rotor were turning. If this is the case, I would think that the helicopter should have been grounded and an engineering (not LAME engineering) examination should have been performed to determine if excessive stresses were experienced due to “Centrifugal forces" on the main and tail rotor blades and the two rotorheads as well as other rotating parts of the drive line. Also the engine should have been torn down to determine if any of the moving parts had been overstressed or possibly stretched.
Not knowing the CAA regs. I would think that there would be a requirement to enter the overspeed occurrence in the aircraft log with further indication of what inspections were performed to clear the helicopter for further flight. Otherwise your inadvertent overspeed may manifest itself at some later date causing harm to the unaware pilots.
Lu :
Not often someone pisses me off, but you've managed it
If you've read the thread properly, you should have picked up that the aircraft didn't fly again. I shut down immediately after the incident. When I got back to home base I wrote up the overspeed in the tech log - this will ground the aircraft until it's been checked.
And, again if you've read the thread properly, you may want to re-read Buitenzorg's post for info on the checks required after an overspeed.
Not often someone pisses me off, but you've managed it
If you've read the thread properly, you should have picked up that the aircraft didn't fly again. I shut down immediately after the incident. When I got back to home base I wrote up the overspeed in the tech log - this will ground the aircraft until it's been checked.And, again if you've read the thread properly, you may want to re-read Buitenzorg's post for info on the checks required after an overspeed.
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NR
the general order is in the manual
the governor i dont think should be turned on at 80% and let go to find its way up because:-
- it may use exessive power to do so,
- it may not be functioning properly.
if the govenor is turned on at 80% i think the throttle should be controled (overridden) by the pilot to ensure a smooth accelleration of the engine and rotor system.
NR -you say the tack's were off the scale, was the engine sounding like it was up there with them??
- also there was a thread a while back on a similare situation with a bigger side effect, i think it was on a thread about active niose reduction headset, the tale boom was severed.
the general order is in the manual
the governor i dont think should be turned on at 80% and let go to find its way up because:-
- it may use exessive power to do so,
- it may not be functioning properly.
if the govenor is turned on at 80% i think the throttle should be controled (overridden) by the pilot to ensure a smooth accelleration of the engine and rotor system.
NR -you say the tack's were off the scale, was the engine sounding like it was up there with them??
- also there was a thread a while back on a similare situation with a bigger side effect, i think it was on a thread about active niose reduction headset, the tale boom was severed.
PPRuNe Enigma
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Well I was originally taught to put the governor on and let it capture from 80% as per the manual.
But: another instructor shortly after that gave me the advice which I now follow, to manually take it to the bottom of the green arc, let it settle and let the governor pick up from there.
This simplifies checking the low RPM horn - I can do that at 97% just before engaging the governor, and most importantly avoids the rapid winding on of throttle that you get when the gov. cuts in from 80% which I must admit had always alarmed me from the point of view of drivetrain stresses and overshooting as seems to have happened here.
But: another instructor shortly after that gave me the advice which I now follow, to manually take it to the bottom of the green arc, let it settle and let the governor pick up from there.
This simplifies checking the low RPM horn - I can do that at 97% just before engaging the governor, and most importantly avoids the rapid winding on of throttle that you get when the gov. cuts in from 80% which I must admit had always alarmed me from the point of view of drivetrain stresses and overshooting as seems to have happened here.
Iconoclast
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Yeah but.....
To: The Nr Fairy
Pissing you off was not my intention. I did note that the instructor had placed the helicopter in an unserviceable status until an inspection was performed. I was speaking in generalities in reference to what must be done in the event of an overspeed and what the outcome could be if the inspection was not performed or if the authorities (in your case the instructor) had not been notified. It was not until I had posted that I went back and saw the post from Buitenzorg in which he stated in greater detail exactly what I had posted.
Now it’s up to you to inform us all as to what was discovered from the check and what checks were performed. That way everyone can learn from your unfortunate experience.
Many years ago I saw an USAF training film dealing with a similar situation in which a hard landing on a P-39 was not reported. The next pilot took the P-39 for a flight and he hit turbulence and lost both wings. Your experience should be a learning experience for all the pilots and mechanics on this forum. Knowing what the results of the overspeed were relative to the corrective maintenance that was required to restore the R-22 to service will make all of them more aware of the possibilities and problems of incurring the same situation.
From what I got out of this thread there is no consensus as how to deal with the start-up of the R-22 and by inference the R-44. Your experience should be reported to Robinson and at the same time the operator of the R-22 should query Robinson to determine if it has happened before.
Pissing you off was not my intention. I did note that the instructor had placed the helicopter in an unserviceable status until an inspection was performed. I was speaking in generalities in reference to what must be done in the event of an overspeed and what the outcome could be if the inspection was not performed or if the authorities (in your case the instructor) had not been notified. It was not until I had posted that I went back and saw the post from Buitenzorg in which he stated in greater detail exactly what I had posted.
Now it’s up to you to inform us all as to what was discovered from the check and what checks were performed. That way everyone can learn from your unfortunate experience.
Many years ago I saw an USAF training film dealing with a similar situation in which a hard landing on a P-39 was not reported. The next pilot took the P-39 for a flight and he hit turbulence and lost both wings. Your experience should be a learning experience for all the pilots and mechanics on this forum. Knowing what the results of the overspeed were relative to the corrective maintenance that was required to restore the R-22 to service will make all of them more aware of the possibilities and problems of incurring the same situation.
From what I got out of this thread there is no consensus as how to deal with the start-up of the R-22 and by inference the R-44. Your experience should be reported to Robinson and at the same time the operator of the R-22 should query Robinson to determine if it has happened before.
Iconoclast
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Don't ask. Don't tell
To: The Nr Fairy
Here is a situation similar to your experience.
Here is a practical example of what can happen when a pilot experiences a compressor stall on a turbine-powered helicopter and does not report it. In this case there were three unreported compressor stalls on an Agusta-Bell 205.
The pilot was instructing a student in autorotations and chopped the throttle. The student did not respond to the situation telling the pilot that the instrument indicated that the engine was still running. By that time the rotor RPM was bleeding off quite rapidly and the pilot dove the helicopter to bring up rotor speed while at the same time re-engaging the engine. The compressor stalls had so damaged the free wheeling unit that the pilot could not engage the engine to the transmission so he elected to make a conventional run-on landing. While the rotor was slowing down the pilot was doing some paperwork when the rotor broke off the mast hitting the pylon and punching the stabilizer bar through the right hand side of the fuselage just missing the student.
The accident report reflected the damaged freewheeling unit and this pointed to compressor stall. Bell Helicopter on the other hand stated that it was the pilots’ fault in making a very rough landing causing the rotor mast to bend backward allowing the rotor to strike the pylon. This theory was blown away by demonstrating that in order for this to happen the fuselage structure would have to yield to allow the rearward movement of the transmission and this was shown not to have occurred. Bell won out and the compressor stall theory was disproved because there was no entry in the logbooks. In the event of a compressor stall the entire driveline and the dynamic system had to be torn down and inspected as well as inspecting the fuselage and this was never done because it was never reported. It was several weeks after the investigation that the engineering manager was approached by the Bell TecRep who told him that he was aware of the three compressor stalls and, he was well aware of the ongoing investigation and the conclusions of the engineering manager yet he never offered this information.
One of the reasons Bell went with their story was that at that time the 206s and HU1-Es had experienced 56 or more mast separations and did not want to worry the customer. Regarding the Bell TecRep I don’t know if he is still working for Bell but the engineering manager left the company and is living in Pincourt, Quebec.
The moral of this story is what if the mast separation had occurred in flight?
Here is a situation similar to your experience.
Here is a practical example of what can happen when a pilot experiences a compressor stall on a turbine-powered helicopter and does not report it. In this case there were three unreported compressor stalls on an Agusta-Bell 205.
The pilot was instructing a student in autorotations and chopped the throttle. The student did not respond to the situation telling the pilot that the instrument indicated that the engine was still running. By that time the rotor RPM was bleeding off quite rapidly and the pilot dove the helicopter to bring up rotor speed while at the same time re-engaging the engine. The compressor stalls had so damaged the free wheeling unit that the pilot could not engage the engine to the transmission so he elected to make a conventional run-on landing. While the rotor was slowing down the pilot was doing some paperwork when the rotor broke off the mast hitting the pylon and punching the stabilizer bar through the right hand side of the fuselage just missing the student.
The accident report reflected the damaged freewheeling unit and this pointed to compressor stall. Bell Helicopter on the other hand stated that it was the pilots’ fault in making a very rough landing causing the rotor mast to bend backward allowing the rotor to strike the pylon. This theory was blown away by demonstrating that in order for this to happen the fuselage structure would have to yield to allow the rearward movement of the transmission and this was shown not to have occurred. Bell won out and the compressor stall theory was disproved because there was no entry in the logbooks. In the event of a compressor stall the entire driveline and the dynamic system had to be torn down and inspected as well as inspecting the fuselage and this was never done because it was never reported. It was several weeks after the investigation that the engineering manager was approached by the Bell TecRep who told him that he was aware of the three compressor stalls and, he was well aware of the ongoing investigation and the conclusions of the engineering manager yet he never offered this information.
One of the reasons Bell went with their story was that at that time the 206s and HU1-Es had experienced 56 or more mast separations and did not want to worry the customer. Regarding the Bell TecRep I don’t know if he is still working for Bell but the engineering manager left the company and is living in Pincourt, Quebec.
The moral of this story is what if the mast separation had occurred in flight?
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Nr. , Don't fret it mate. Every one makes a mistake. Poor consolation I know, but congratulate yourself on doing the right thing after the occurrence - re:telling someone.
I read in the AAIB website a while ago about an R22 crash where the cause was a recent undisclosed overspeed - I think the lower part of the conrod broke away from the crank shaft or something due to the earlier overspeed. Not good.
As for my part I always wind the throttle up to 90%+ manually before flicking the governor on just so there's not that sudden surge of throttle as the governor grabs it...
If this makes you feel any better, I've heard of a guy doing a 12 month checkride who got in an R22 and started it up on full throttle.... and it was several seconds before he realised why the engine sounded so loud ...
I read in the AAIB website a while ago about an R22 crash where the cause was a recent undisclosed overspeed - I think the lower part of the conrod broke away from the crank shaft or something due to the earlier overspeed. Not good.
As for my part I always wind the throttle up to 90%+ manually before flicking the governor on just so there's not that sudden surge of throttle as the governor grabs it...
If this makes you feel any better, I've heard of a guy doing a 12 month checkride who got in an R22 and started it up on full throttle.... and it was several seconds before he realised why the engine sounded so loud ...
Senis Semper Fidelis
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NrF,
You have my deepest sympathy, but also you have my absolute admiration, for you elected to stay on the ground and tell some one! that was a shinning example of doing it right, I have had the misfortune of being the next pilot to take off in a R22 that had suffered from an overspeed exactly like you have explained, only the people who knew about it" thought it would be alright" after a flight of four minutes and a vibratory induced sterilisation I was fortunate to be able to land, but could not feel any of my limbs for about twenty minutes.
I repeat I admire your ability, but I am sorry that it will cost you dear.
Many regards
Peter RB
You have my deepest sympathy, but also you have my absolute admiration, for you elected to stay on the ground and tell some one! that was a shinning example of doing it right, I have had the misfortune of being the next pilot to take off in a R22 that had suffered from an overspeed exactly like you have explained, only the people who knew about it" thought it would be alright" after a flight of four minutes and a vibratory induced sterilisation I was fortunate to be able to land, but could not feel any of my limbs for about twenty minutes.
I repeat I admire your ability, but I am sorry that it will cost you dear.
Many regards
Peter RB
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Yes.
I put it into a field pdq, glad to be on the ground.
Was assured by the operator that it was an intermittent fault on the machine (!!). After some persuasion, flew it back a 3/4 miles back to the home airfield - probably a mistake, but no problems.
why do you ask?
I put it into a field pdq, glad to be on the ground.
Was assured by the operator that it was an intermittent fault on the machine (!!). After some persuasion, flew it back a 3/4 miles back to the home airfield - probably a mistake, but no problems.
why do you ask?
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The other day, I saw a chip detector pulled from a main transmission that was covered with metal....
and the light did not go off....
The reason the plug was pulled was a grinding sound noted during coast down...
The electrical system worked, and this was not the first time the operator has noted this problem with the chip detector.
In the past, the chip detector was cleaned, and checked for continuity, with no faults found.
Theories abound about sludge in the oil acting as an insulator...the chip plug is on the bottom of the transmission with no oil flow around it...
Just wondering if anyone had an experience with the system working properly....
and the light did not go off....
The reason the plug was pulled was a grinding sound noted during coast down...
The electrical system worked, and this was not the first time the operator has noted this problem with the chip detector.
In the past, the chip detector was cleaned, and checked for continuity, with no faults found.
Theories abound about sludge in the oil acting as an insulator...the chip plug is on the bottom of the transmission with no oil flow around it...
Just wondering if anyone had an experience with the system working properly....
I've since spoken to a guy who runs Robinson safety courses in the UK, and after our conversation I've put together this little blurb as there seem to be all sorts of differing ways that people use for the last moments before going flying. He's most amenable to speaking to complete strangers about flight safety - if you feel theneed, let me know and I've got his contact details ( thanks Whirlybird ).
The last items on the POH "Starting Engine and Run-up" checklist for the R22 ) page 4-7 ) are:
Cyclic/Collective Friction .... Off
Governor on ..................... RPM 102% - 104%
Lift collective slightly ......... Horn light at 97%
Now, that last but one item is a bit ambiguous. Here's the advice from as close to FR as you'd like:
1. Do all the mag checks and needle splits at 75% - my understanding is that this is for noise reduction.
2. When ready, at 75% turn the governor on. Roll on throttle, ensuring the governor captures at 80%. RELEASE BUT GUARD the throttle until RPM stabilises at 104% - if it runs away upwards, you can catch it before it goes BEYOND LIMITS.
3. At 104%, roll off a bit of throttle and ensure the governor takes RPM back to 104% - at this point I suppose you could also do the RPM horn check.
4. Roll on a SMALL amount of throttle - 1 or 2 percent - to ensure the governor brings the RPM back down. POH allows momentary transgressions into the red band.
After that, you're all ready to fly. Why has this been promoted as the way to do it, and what other considerations are there ?
Firstly, you're not doing two things at once, i.e. switching the governor on AND rolling on throttle, so you can monitor RPM rise.
Secondly, this is a critical phase - you're just about to go flying - so unneccessary distractions should have been sorted out before now. Total concentration on getting to operating RPM then lifting safely is crucial.
One of the problems with the governor is that is has made the pilot less aware of the RPM because it is assumed that the governor will maintain 104% automatically. It will for most of the time, but it's not infallible. Remember that the RPM gauge is a PRIMARY instrument. Look after the RPM and everything else will look after itself.
As an aside, we discussed briefly the issue mentioned by Buitenzorg where it's possible that the machine can spin on a slick or icy ramp and Grainger's concerns about overstressing the drive train. The advice is that normally the MP doesn't need to be controlled to avoid overstressing the drive train but a slick / icy ramp may need the throttle guarding to prevent a spin.
Hopefully, I'll not overspeed a Robbie again - if I do, it might be worth looking at less expensive hobbies, like burning £50 notes.
The last items on the POH "Starting Engine and Run-up" checklist for the R22 ) page 4-7 ) are:
Cyclic/Collective Friction .... Off
Governor on ..................... RPM 102% - 104%
Lift collective slightly ......... Horn light at 97%
Now, that last but one item is a bit ambiguous. Here's the advice from as close to FR as you'd like:
1. Do all the mag checks and needle splits at 75% - my understanding is that this is for noise reduction.
2. When ready, at 75% turn the governor on. Roll on throttle, ensuring the governor captures at 80%. RELEASE BUT GUARD the throttle until RPM stabilises at 104% - if it runs away upwards, you can catch it before it goes BEYOND LIMITS.
3. At 104%, roll off a bit of throttle and ensure the governor takes RPM back to 104% - at this point I suppose you could also do the RPM horn check.
4. Roll on a SMALL amount of throttle - 1 or 2 percent - to ensure the governor brings the RPM back down. POH allows momentary transgressions into the red band.
After that, you're all ready to fly. Why has this been promoted as the way to do it, and what other considerations are there ?
Firstly, you're not doing two things at once, i.e. switching the governor on AND rolling on throttle, so you can monitor RPM rise.
Secondly, this is a critical phase - you're just about to go flying - so unneccessary distractions should have been sorted out before now. Total concentration on getting to operating RPM then lifting safely is crucial.
One of the problems with the governor is that is has made the pilot less aware of the RPM because it is assumed that the governor will maintain 104% automatically. It will for most of the time, but it's not infallible. Remember that the RPM gauge is a PRIMARY instrument. Look after the RPM and everything else will look after itself.
As an aside, we discussed briefly the issue mentioned by Buitenzorg where it's possible that the machine can spin on a slick or icy ramp and Grainger's concerns about overstressing the drive train. The advice is that normally the MP doesn't need to be controlled to avoid overstressing the drive train but a slick / icy ramp may need the throttle guarding to prevent a spin.
Hopefully, I'll not overspeed a Robbie again - if I do, it might be worth looking at less expensive hobbies, like burning £50 notes.
The Original Whirly
Join Date: Feb 1999
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Nr Fairy,
Thanks for that. I went flying yesterday, and remembering your experience I did more or less just that - monitored the RPM carefully as the governor took it up into the green. It occurred to me then that I should always have been doing that, as no instrument is infallable - but you do what you're trained to do unless you see a reason to change it. So many thanks for bringing this to everyone's attention. And having had one overspeed myself (and I agree, burning £50 notes would be a lot more fun
), I'm extremely concerned to avoid another one.
Thanks for that. I went flying yesterday, and remembering your experience I did more or less just that - monitored the RPM carefully as the governor took it up into the green. It occurred to me then that I should always have been doing that, as no instrument is infallable - but you do what you're trained to do unless you see a reason to change it. So many thanks for bringing this to everyone's attention. And having had one overspeed myself (and I agree, burning £50 notes would be a lot more fun
), I'm extremely concerned to avoid another one.