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marrty41

governor

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Sitting with my instructer the other day with 75%rpm in the 22 and I engaged the governor switch nothing happened looked round to him and he informs me that unless we are at 80% nothing will happen.How does the governor work and is it foolproof just curious?

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Well, I can give you the basics, as that's all I know myself.

 

Basically you have a control unit that senses the engine RPM thru the right mag (points) The rotor RPM is sent to the control unit thru a magnetic pick-up at the main transmission input shaft. The control unit then somehow decides what needs to happen and adds or removes power thru an electric motor that turns the throttle. The control unit also decides when to engage and disengage itself (80%) I believe this is preset and can't be changed in the field

 

No, they aren't foolproof, that's why we have a switch to shut it off if need be. I had one that wanted to maintain 108% (in the red) instead of 104% There is high and low side that the governor tries to maintain, something like 102% to 105%, not sure of this though, and I believe that this can be adjusted in the field.

 

Hope that helps

 

Fly Safe

Clark B)

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The rotor RPM pickup, Tach, or Low rotor RPM system all have nothing to do with the throttle governor.

 

The governor gets its imput soley off a second set of points in the right (co-pilot's) side magneto. They run to a control box behind the co-pilot's seat. When the governor is switched ON, it is active between 80-110% ERPM. The governor will maintain the factory set engine RPM (2652?) +/- a few pecent, regardless of what the tach says. In fact, the way you calibrate the tach is to turn the governor on and adjust the tach needle to the top of the green.

 

Back to the mechanics of it.....Again, behind the co-pilot's seat, there is a pigtail from the control box to a small actuator. The arm from the actuator is connected to the throttle bar that run between the to grips. When ERPM gets low, throttle is increased and vice versa.

 

A little about the "GOV OFF" light, this was an after thought and it gets it's power off the governor switch. It has no idea whether or not the governor is actually working, just if the switch is on or off.

 

Now the rotor RPM system. The tach indication and the low rotor RPM system are completely separate from each other as well. If you look under the MR driveshaft flex coupling, you'll see two magnetic pickups. One goes to the tach, the other to the low rotor RPM warning system.

 

The low rotor RPM system is a control box underneath the instrument console. It's set to activate the light and horn at a set driveshaft RPM which equals 97% RRPM (used to be 90%). Like the governor--since it's factory preset--you use this system to adjust and calibrate the tach to read 97% when the horn and light activate.

 

The tach....The tach has seperate circuit breakers for each side (engine and rotor). For the rotor RPM side, it will be powered as long as you have one or more of the following switches in the ON position: Master battery, Alternator, and/or Clutch engaged. So if you have an electrical fire and turn off your battery and alt, the RRPM side of the tach will still work. You will lose the low rotor RPM system and the governor though.

 

This is one of the reasons why it is considered an inflight emergency if your alternator goes out. If you lose it, and the battery goes dead, your RRPM tach will not be powered along with the other systems. The other [main] reason it's an emergency, the alt belt catching fire from a frozen pulley or getting shredded and thrown into the main drive belts.

 

But do you see a trend? All three systems--the governor, the low rotor RPM system, the both sides of the tach--are all independant of each other. If you lose any one (or two), you will still be able to know where the RPM is or when is getting low.

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Delorean,

 

OK, I want to make sure that I understand this. I'm on board with everything you say, but I am confused with Rotor RPM not being part of the Governor. Does the wiring for the Low RRPM and RRPM Tach go thru the control unit for the governor? I've attached a drawing that I have of the R22 governor system, and to me it looks like the RRPM is part of the governor control unit.

 

Not arguing, just asking, I know you have alot more knowledge of the systems than I.

 

RobinsonR22.pdf

 

 

I am going to get as good as you at explaining this stuff, even if it kills me!!!

Have time for some tutoring? :huh:

 

Fly Safe

Clark B)

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Can't speak to the R22, but in all the helos I've flown you can think of the throttle as a valve that limits the maximum fuel to, and thus power available, from the engine. You can reduce NR out of the governed range with throttle on those, which could be a response to a high-side governor failure. Several models I've flown require that the throttle be opened to the max normal position so that the governor has full throttle control.

 

The Astar's a little different, in that you can advance the ECL (analogous to a throttle) through the full throttle governed range, taking the fuel control out of the loop if it fails.

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Delorean,

 

OK, I want to make sure that I understand this. I'm on board with everything you say, but I am confused with Rotor RPM not being part of the Governor. Does the wiring for the Low RRPM and RRPM Tach go thru the control unit for the governor? I've attached a drawing that I have of the R22 governor system, and to me it looks like the RRPM is part of the governor control unit.

 

Not arguing, just asking, I know you have alot more knowledge of the systems than I.

 

RobinsonR22.pdf

I am going to get as good as you at explaining this stuff, even if it kills me!!!

Have time for some tutoring? :huh:

 

Fly Safe

Clark B)

 

What's the revision date on the bottom of that drawing?? It was cut off the scan in some petty attempt to upstage me. Nice try, but not today.......hahahahahaha.

 

If it's prior to 94-95, that explains why it has the rotor RPM pickup illustrated on it. The old system would move the collective up and down in addition opening and closing the throttle. Really screwy system similar to the R44A's automatic force trim. Never knew if it was the instructor or the machine fighting you on the controls.

 

I don't have a maintenance manual or any wiring diagrams for the Robinsons anymore, but I know for a fact that the RRPM does not go into the governor control box for the R44. I'm almost positive that the same for the R22. Take a look at the current wiring diagram and let us know. The hall effect sensors should be toward the upper right side of the diagram and the governor control box to the lower right of the center point.

 

"You know, I thought I was wrong once......but it turns out I was mistaken about that." :D

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What's the revision date on the bottom of that drawing??

 

No revision date on it. This is from a handout that I received at the RHC safety course in June of this year. You would think that the factory would be handing out only current and up to date material, not long forgotten systems from the 80's!!! I've heard of the system you speak of Obi wan, but never had the honor (or horror) of trying to fly with it. I bet you're right though, the diagram would make sense that way. I don't have access to a current maintenance manual right now. Next time I do, I'll try to remember to look it up.

 

 

"You know, I thought I was wrong once......but it turns out I was mistaken about that."

 

Yep, I thought that too......... then I started hanging out here........ now I'm not sure of anything anymore :huh:

 

Fly Safe

Clark B)

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So if you had no electrical power the governor would not work but the correlator would.

 

Correct. The correlator is a mechanical linkage. Kneel down on the left side of the helicopter and watch the throttle linkage as you move the co-pilot's collective up and down. You'll see it go from full closed at the collective down stop to [almost] fully open at the collective up stop.

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The governor gets its imput soley off a second set of points in the right (co-pilot's) side magneto.

so, does the engine tachometer get its signal from the right (co-pilot side) magneto also or the left (pilot side) magneto?

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so, does the engine tachometer get its signal from the right (co-pilot side) magneto also or the left (pilot side) magneto?

 

Yes, the engine tachometer signal is from the same contact assembly ("points") used by the throttle governor (within the engine-right magneto on the helicopter's left side).

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Yes, the engine tachometer signal is from the same contact assembly ("points") used by the throttle governor (within the engine-right magneto on the helicopter's left side).

Thanks. The only reference that I can think of for this would be a Robinson maintenance manual. You know of any online references for this?

Not that I don't believe you; I just like to have references that go along with what I know.

I might end up getting myself a maintenance manual.

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Thanks. The only reference that I can think of for this would be a Robinson maintenance manual. You know of any online references for this?

Not that I don't believe you; I just like to have references that go along with what I know.

I might end up getting myself a maintenance manual.

No offense taken; in fact, kudos for performing such fact-checking "due diligence".

 

You are correct-the Maintenance Manual (MM) has the relevant info, specifically R22 MM Figures 14-2N (the big foldout) and 14-6E.

 

I do not know of any online schematics for the R22/R44 but an email to RHC Tech Support (http://www.robinsonheli.com/rhc_technical_support.html) will get you your own copy (of a schematic, not the entire MM) pretty quick, and without spending any money.

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 Governor failure

Good morning. Can you help me please.
After the start and heating, ther is a bad situation. the light of Governor do not turn OFF.

At a certain point the interruptor and light seems working correctly but over the 80% RPM, the Governor do not start.
It is the control unit?
Thank You

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On 1/2/2020 at 7:49 AM, Maurizio said:

 Governor failure

Good morning. Can you help me please.
After the start and heating, ther is a bad situation. the light of Governor do not turn OFF.

At a certain point the interruptor and light seems working correctly but over the 80% RPM, the Governor do not start.
It is the control unit?
Thank You

Delorean’s post above gives an excellent description of the system. 

The system is fairly simple. You have a solid-state control unit mounted behind the left seat back. The controller senses engine RPM via tachometer points in the engine right magneto and provides a corrective signal to the governor assembly. 

The governor assembly gearmotor is attached to the collective stick assembly behind the left seat. When activated by the controller, the gearmotor make the required RPM adjustment by driving a clutch connected to the throttle. 

The following is a quote from the R22 maintenance manual:

“The majority of governor problems are caused by the engine's right (helicopter left side) magneto tachometer contact assembly (points) being out of adjustment or faulty.”

Garbage-in garbage-out, engine right magneto or wiring problems upstream of the controller can result in strange or intermittent issues. The controller may not be the problem.

Check out the link below pages 8.34A RPM Governor System and 8.34C Governor Troubleshooting

https://robinsonheli.com/wp-content/uploads/2018/11/r22_mm_8.pdf

click photo to enlarge

spacer.png

Edited by iChris

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