R44 - Governor Goes mental

[generalspecific]

Thoughts and suggestions please..
Started the 44 today, run up normal governor confirmed on and then up through 80%.. governor took it and engine and rotor rpms ran up normally until the engine was at about 88% then there was an engine only needle spike for about 1 second of about 5% (this was a guage spike as there was no accompanying engine note increase).. then it settled down and ran up as normal to 102% engine rpm.
Ran the low rpm check.. light and horn ok and then a normal run back up to a governed 102%.
P's and t's green lights out (i.e governor on) and into a stable 4 foot hover. Sitting in the hover checking the greens one more time and wham... the governor grabbed the throttle and snappped it wide open ( i can only describe the force of motion as the same as when the governor takes hold at 80% and runs the engine to 102%)... engine and rotor rpm heading for the moon in a hurry so i snapped the throttle closed for a hover auto..
Following ground runs we cpould not replicate the 88% engine rmp needle spike or the governor run away, but the govvernor is no governing at the 104% red line...
Now with the engineers while they check out the governor and the engine and rotor overspeed which luckily was minor as i was staring at the guages when the run happened...
Has anyone heard of this or had it happen to them?? Reiterate, the governor was on, the hover was stable, there was no change to the collective pitch nor any pedal movement prior to the event.. it just ran..
I can only describe it as like the governor trying to run the engine up from 102% to god knows where in the same way it does from 80-102%...
Sure got my attention :eek:

[misterbonkers]

mobile phone interference?

[JimBall]

Could be: oil in the magnetos.

The "governor" (it doesn't govern, it is easily over-ridden) has a sensor in the magnetos which can be dirtied by oil. Had this happen straight after a 100H check whilst doing the ground run - the engine/rotor started to run away, so closed throttle. Shut down. Restarted with engineers watching avidly and it happened again.

Turned out that an engineer had been too liberal with oil in the magnetos.

If it ain't broke.........

Check and let us know.

[generalspecific]

phone was off... oil in the mags is a thought, the engineer cited a mag problem as a possible..

will keep you informed

[Dr Mark Cowley]

I have had the same thing happen over the years. It was found to be a hairline crack somewhere in the magnetos, that opened up when it got warm after a few minutes running. It sent the engine rpm haywire

[Great View]

It's most likely a mag problem, your governor gets its "RPM signal" from a second set of points in the R/H mag (if I remember correctly). When you have a governor problem, the mag is the first thing to check and 90% of the time, the mag is the culprit. I have had, on a couple of occasions, the governor control box go out on me (which is rare but does happen).It resulted in a gradual increase in rpm and was easily detected by the pilot. Its located behind the L/H rear seat back and is (except for one screw) quite easily replaced.
I'm curious to see what they find, so keep us posted.

[helimutt]

Not sure if the governor systems are the same on R22 and R44 but once saw a governor run up very quickly on R22 and the fault was in the governor box itself. Soon as you let go the throttle it would drive straight upwards too quickly for a low time student to catch.

[generalspecific]

this was definately a throttle through the roof job... frustratingly a ground run failed to replicate the fault but the governor is now governing to 104% not 102%..

Thanks for all the helpful posts, at least i know I am not going mad and after some overspeed checks and the removal of the seat cushion from my butt.. looks like no harm done..

[uttanutta]

Could be a sticky fuel servo, they seem to stick around 80-90% then lets go and governor struggles to catch it. Only seems to do it on first start and can not be reproduced when engine is warm. Fuel servo has be removed and sent for repair.

Good luck.

[3top]

Okay,

if it was a run-away as described, it was possibly a cut or shortened wire from the points in the right mag (actually on the left side in the helo).
The rpm signal comes from a set of points in that mag. The signal wire gets occasionally trapped between the rather sharp edge of the condenser (?..) and the mag cover. Vibration takes it to the wire and you get shorts, with a loss of signal, which the governor reads as low-rpm. Sometimes you can't find this one, as you open the mag cover all looks good. You have to really look close. IF you find the pinch a layer of electrical tape will do until you can replace the signal wire.
Watch the wire routing! Don't get it pinched again.
Oil in the mags is another one. Not always from too much grease in the mag, but from shot mag seals to the engine.

Same thing happened to me with an intermitent "hunting" of the mag - pinched wire.

Despite it seems rather fast the governor is actually slow.
You can check this yourself. When ready for take-off raise the collective rather quickly (still smooth, please!!) and you will raise the rpm, as the correlator is acting way faster than the governor.
Same goes the other way. Just barely touch the ground and lower the collective quickly (see above!!) and rpm comes down.
Governors go out rarely...but you never know.
I would chase the signal wire first, then the points....

Let us know how this one ends!

3top, :cool:

[BHenderson]

Does the governor take at 80% or 82%? The R44 I fly occasionally runs at 104% engine, 102% rotor, taking at 82% at run up.

[3top]

Bhenderson,
if the rotor and engine show a split like that, your mechanic needs to adjust the dual needle indicator...
3top

[chopperpug]

I have also had the wire to the points in the mag short out, similar results. Main reaction, don't panic and override the Governor, its not the be all and end all of the R44. But same reason, when the points were put in, the wire was poked behind the condenser and slowly rubbed. Was a bit to track down though, becuase as previously stated, its not always obvious on first inspectoin, so we had changed the Govenor box and tried various other things before hunting this one down. Was just erratic though, it didn't run away past 110%, varied between 108 and 96.
Did have another erractic govenor problem with which the end result was a friction problem with the govenor motor itself located behind the front pax. There is a friction washer that is a factory preset friction, and not (according to maintenance manual) adjustable in the field. Replaced the whole govenor motor and problem solved.
Just as an aside on mags, had two newly overhauled mags put on, and within 45 hours, both went at the same time. Had a rough running engine for approx 8 hours, and was trying all sorts of solutions in discussion with our engineers, wasn't really fouling plugs, timing was good on the ground. Then had one mag fail completely, just on take off roll, and the second go the moment I ran on. Turned out the main set of point in each mag, the wire had been overcrimped, and bent, and a little vibration fractured the wires (Most likely the burping and carrying on that they have a tendancy to do whilst ground running, and then as it go more intermittent, more and more vibration and so on, and evenutally shorted out permanently on the mag casing. Was an interesting afternoon.
chop.

[helifixer]

Change your governor control box! Another hint: You shouldn't be diagnosing your helicopter faults on a rumour forum.

[JimBall]

You shouldn't be diagnosing your helicopter faults on a rumour forum

On the other hand - it helps to spread the word and, in this case, makes pilots concentrate on start-up. The number of pilots who start an R44 like it is their car - on the phone, chatting to pax, eyes not on instruments.

[VeeAny]

Helifixer

Whilst you do have a point, I Always read these threads with great interest, as they tend to make others who have had similar problems come out of the woodwork, and usually point out some valid places to look and generally serve as a good starting point for places to go and have the engineers look, if they don't already know.

No I am not engineer, but a pilot with an interest in all things technical.

GS

[bvgs]

Helifixer, don't really see "generalspecific" standing there mouse in one hand tools in the other waiting for instructions to fix his problem. These forums are a great wealth of knowledge and by people sharing their experiences can aid and assist others.

[generalspecific]

Agree....we have very competent engineers to find and fix these things. I'm just the chimp what flies it!

Simply never had a governor try to run away with me like this and was simply wondering via forum wisdom whether anyone else had anything like this.

As usual the forum has proved its worth!

Thanks to all and I'll let you know what the engineers finally diagnose.

[3top]

chopperpug,

I like your use of the word "interesting" :):)

3top:cool:

[3top]

GeneralS and all others,

watch your MR blades on the R-44.
In my backyard (Pacific Ocean :)) there where another 2 cases of MR leading edge delamination (leading edge of the upper skin pulls up from the Stainless leading edge/spar, basically a glue failure).
Times around 1100 to 1200 hrs.
The latest one was only about 4 nm from the boat, but the pilot had to put it in the water - ship survived. He said he never had anything vibrating so bad :*

You might blame this on the salt and tunaboat environment, but I spent 3800 hrs out there and wore out 2 helis. NEVER any problems with the blades and these where really badly worn.....

Supposedly the blame is with the operator, ....says Frank &Corp.

3top:*

[chopperpug]

Oh, and I should have pointed out that the mags were overhauled at a major facility that does hundreds of these, lest anybody thinks I was putting dispersions on the fantastic engineering staff at the place I was working for at the time. (Forget buying the chief pilot a beer, use your minimal wage on keeping the engineers happy, they will keep you happy) And yes, it was an afternoon to keep me entertained. Trying to explain what had happened to a couple of foreign language people who did not understand much english was a very amusing exercise. To this day I think they still think that I turned the engine off deliberatley. :}
Where I was at the time also had a lot of issues with the new Stainless blades, as has been talke about in other threads. I was lucky enough to get out of flying 44's before these came in. Not much chop for bush work, one small twig and there it goes.... you can see the money roll past the bosses eyes. Much thinner and much less tolerance for any damage.
Anyway.. thats well off topic.. sorry.... not much else to do up here at the moment.. too hot for most people.
chop

[generalspecific]

Weeel ladies and gents... the aircraft is back on line and sure enough it was a right mag problem.

The oil seal between the back of the engine and the right mag had cracked and allowed oil into the mag which had pooled and "drowned" the sensor giving eroneous readings to the governor (which then tried to open the throttle wide when we were already at 102% engine rpm).

All fixed and thanks very much to all who helped point us in the right direction

[500e]

Nasty fault that could be very costly,correlator and twist seems a least problem scenario.

[thekite]

Are you always so parsimonious? Looking for advice on PPrune is incredibly worth while. :=

I recently was advised (thanks to Eric Ferret) what was wrong with the Hiller I had been flying in 1981, when it tried to kill me on 3 occasions.

CASA couldnt help, none of the heli LAMEs in Bankstown could help, and my boss sacked me for talking to CASA! Even Ray Prouty could not come up with an idea.

Read more; scold less. And have a nice day...:E

thekite

[topendtorque]

Hey Kite
you haven't bin checking your PM's.

also;-

the Hiller I had been flying in 1981, when it tried to kill me on 3 occasions.

CASA couldnt help, none of the heli LAMEs in Bankstown could help, and my boss sacked me for talking to


Maybe you weren't carrying your bible like your boss was reputed to?????

That's if it is the Hiller outfit that i'm thinking of.
cheers tet

[3top]

quote:
also;-

Quote:
the Hiller I had been flying in 1981, when it tried to kill me on 3 occasions.

CASA couldnt help, none of the heli LAMEs in Bankstown could help, and my boss sacked me for talking to....

Maybe you weren't carrying your bible like your boss was reputed to?????

That's if it is the Hiller outfit that i'm thinking of.


You got to be kidding!!

The bible is/was a basic outfit for the HIller?? :eek:
Well, then you really don't need a POH anymore.

Just a pair of legs, ...to run fast! ....as far away from the beast as possible!

3top :cool:

[thekite]

No, did not see a bible, although if divine intervention was involved, it might explain why Stanley Hiller never saw reason to fit chip detectors.
tk

[rockpecker]

Yip, had the same thing happen in a R44 Raven 1 a few years ago. After initial rev runaway, the governor continued hunting, and I turned it off and flew RPM manually back to base. All OK in cruise but not nice once you start changing power settings and trying to control RPM in the hover. I was spoilt by never having the opportunity to fly anything other than machines with governors, probably old news to the more senior pilots out there, so once that governor is gone, it is sorely missed. Turned out to be the governor control unit itself. From then on, no assumptions, check the needles as they go up, as in a turbine start.

[topendtorque]

Seriously, it is an event that has happened often enough and as shown in the thread there is no redundancy, except for the bible.

Therefore the redundancy package MUST BE:
THAT PILOTS WHO LEARN ON SUCH MACHINES ARE TAUGHT TO HANDLE SUCH MACHINES WHEN THE BLESSED THING FAILS.

It's only a small ask, and no I am not shouting, just stating the bleeding obvious.

If pilots have to take up to 105 hours to get a CHPL surely this can done during the routine to break the boredom, instead of us guys at the coal face having to spend money insuring our machines safety with extra training.

[Evil Twin]

Funny you should mention being taught manual rpm control.
I only ever done one mini circuit with the govenor off during my instruction to simulate a govenor failure. However, on my PPL flight test as we left our confined area to fly back to the airfield my examiner switched off the govenor and announced 'govenor failure'. Initially I didn't find this too bad, straight and level, then decending back past the tower towards the hangar starting to get busy keeping the needles in the green. Then this is what he made me do, all with the govenor off:-

Come to a 3 foot hover in front of the hangar
Maintain a 3 foot hover while reducing throttle and therefore RRPM to 90% without decending and without pulling more than 24 inches
Sit there at a 3foot hover with the RRPM horn blaring away in my ear for what felt like forever, but was probably only 10 seconds
Bring the RRPM back up to the green without decending and without pulling more than 24 inches

Once stabilised he then switched the govenor back on and I was allowed to land and shut down.
I reckon I sweated more in those few minutes than I'd ever done in all of my flying.:eek:
Thankfully I passed, but what a lesson that was.
Cheers ET

[topendtorque]

Evil Twin
I think you should solemnly thank your examiner for suiting you to the improbable in later life. not only in robinsons do you have the problem of governor control failing; there have been a few threads on B206 fuel control units in the same vein. and other threads testify to similar problems on more complex machinery, all of which would be much easier handled by a pilot that was exposed as you were if not much more to your redundancy training.

My point is that we seem to be accumulatiung a long list of skills that newbie pilots are NOT trained in.

Like; the above; like not recoginsing VRS and how to recover from it; like not being able to safely establish hover OGE well away from fixed visual cues in VMC; like not being able to land the machine when both fuel tanks or only the one fuel tank was filled with defect fuel and the engine /engines later quit; The list goes on.

where are we going with all this? certainly to a head first credibility crash as number one. I.E. destroying the image of the helicopter as a good vehicle in the public's eyes.

I believe that the OZ training establishments received a brand new training manual recently. It would be interesting to hear if any of regular instructors could tell us that I am wrong.
tet

[Jonnyboui]

Looking at some previous points raised on here I can see Im in the right place.

We have an R44 II (Raven) that has developed a problem, i will detail a bit of background first to give 'a bigger picture'

The ship had an over-speed and as a result the engine was removed and the relevant inspection and rectification was carried out. The aircraft was returned to service with both engineers and pilots 'happy' that the ship was serviceable.
The ship has since flown approx 15hrs and has developed a problem. On the first application of power into the 'governor range' 80-102% (not on start up) but regardless of if the governor is on or off we have 'rough running' at 90-95% power and the engine 'hangs' with some harsh vibration. A second later it will clear very harshly causing the ship to yaw and accelerate and try to over speed. This happens the majority of the time but not every time and does not occur in normal flight the problem does not occur unless the engine RPM is dropped below 80% and then bought back in again for example during auto-rotation checks and again the recovery tries to put the ship into an over-speed situation.
It only occurs during this specific and small band of the power range and also the rough running does not sound like a tappet or sticking valve, it sounds more like a rev limiter on a car to use crude terminology.

[FSXPilot]

get the magnetos checked out by an O/H facility. Failing that send the governor away to be checked.

[JimBall]

Oil contamination in magneto. Broken "P" wire. Problem with terminal at magneto.

[Shawn Coyle]

Did all of you send in Service Difficulty Reports???

[nowing]

I had a similar problem when the engine tach points failed, the machine was nearly unflyable with the governor on. Had to switch off the governor and fly manually which turned out to be a good exercise anyway.

I would be checking the points first up, cheap fix as well.:ok:

[Jonnyboui]

Hey guys, thanks for the input.

Have just had loan (overhauled) serviceable mags fitted and the problem is still there, it makes no difference if the governor is switched on or off. Are now thinking of looking at fuel servo or flow divider!

Just to add also that ship during normal flight is fine, when the engine RPM is dropped below 80% the fault occurs again, you can imagine what that was like recovering from an auto-rotation! So the fault is only there during that narrow power band between 80-95%.

[waragee]

I'd be very suspicious of the fuel control unit, perhaps take it off, inspect all, particularly o rings and refit it.

[flyingrobbyspanner]

I have changed the flow divider for a similar problem in the past .
It may be worth looking at if the normal things dont solve the problem.:ok:

[Jonnyboui]

Just had the Fuel Injection Servo inspected and tested, no fault was found. We have a loan unit coming just to make sure though, inspected the nozzles and they were fine. Anymore thoughts?

[flyingrobbyspanner]

At this stage you have to change the flow divider / fuel spider on top of the engine.

[Jonnyboui]

Hi All,

Just for information, despite having our fuel injector servo bench tested (basically a flow and leak check) and no fault found, a new fuel injector servo was fitted and the problem was resolved. Just to confirm this the original servo was refitted and sure enough the problem came back. Fitted the new and problem did not occur. Very strange fault this one!

We are hoping Precision Airmotive will be able to supply a report as to the fault with the original servo when it is overhauled. By the way they were able to provide an excellent price for a factory new fuel injector servo direct from the states.

[handbag]

I thought this thread was going to be about Frank:E