Need help for my cyclic vibration

[Henry_GyroLife]

I have AutoGyro NTO sport 2017 with rotor head sytem 3. The current hobbs read is 470 hours. I recently replaced sim washers for rotor and my cyclic has very small vibrations in a straight flight, but it getts more vibrations on take off, in turns and in vertical descending. Do I have to replace bushings on the rotor and rotor tower ? What hours should I replace these bushing normally ?

 

[Vance]

Follow the maintenance manual Henry.

I have replaced the teeter bushings and teeter bolt on several Cavalons.

Lubricate them often and they will last longer.

Even with proper lubrication the bushings and bolt have a limited life.

I don’t remember what the schedule is; just follow the recommendations.

There are also specifications for the bolt wear although we always replaced it with the bushings.

If I put my finger on the bolt and rotor head and someone twisted the blade back and forth I could sometimes feel the play, sometimes not.

As I recall AutoGyro USA has a tool available.

We made our own.

 

[Strike]

ILThe bushing system that mto uses is truly absurd!! It has NOTHING mechanically!! All models use bearings or real bushings suitable for this purpose, but they still use bushings today with PTFE coating definitely not suitable for this purpose! Difficult to maintain! Difficult to find! Incredible 🥴

 

[Brent Drake]

Almost sounds like a propeller out of balance. Check it for nicks and such.

 

[Henry_GyroLife]

Follow the maintenance manual Henry.

I have replaced the teeter bushings and teeter bolt on several Cavalons.

Lubricate them often and they will last longer.

Even with proper lubrication the bushings and bolt have a limited life.

I don’t remember what the schedule is; just follow the recommendations.

There are also specifications for the bolt wear although we always replaced it with the bushings.

If I put my finger on the bolt and rotor head and someone twisted the blade back and forth I could sometimes feel the play, sometimes not.

As I recall AutoGyro USA has a tool available.

We made our own.

Thank you, Vance. I thought so too. I checked the manual, but there is no specific hours to replace these bushings. I contacted AutoGyro USA and they mostly think it is due to excessive wear of bushings.

 

[Henry_GyroLife]

ILThe bushing system that mto uses is truly absurd!! It has NOTHING mechanically!! All models use bearings or real bushings suitable for this purpose, but they still use bushings today with PTFE coating definitely not suitable for this purpose! Difficult to maintain! Difficult to find! Incredible 🥴

Sure it needs more maintenance, but it is so simple and robust.

 

[Henry_GyroLife]

Almost sounds like a propeller out of balance. Check it for nicks and such.

Thanks for your suggestion. My prop is in valance pretty good. I think it is related to my rotor system.

 

[Abid]

Henry
I believe MTO tetter tower bushing is supposed to be replaced every 200 hours.
The problem with AG system is they are relying on the bushing and the teeter bolt to be the bearing surface. Averso has bearing in the teeter block and we use oilite bushings within the teeter tower. The bearing is the bearing and the bolt does not act like a bearing surface and can be tightened snug. Thus the bolt never has to be turned. In AG system every so often you have to rotate the teeter blt a quarter turn to make the bolt wear evenly.
In this kind of system it is next to impossible to keep the same rotor track and balance for a long time as even a thousands of a wear point will create a tracking issue. This does not occur with other systems using bearings. You should try changing the bushings. That may make things better. But ideally whenever you change the bushings or even whenever you rotate the teeter bolt you are getting away from your dynamic balance and have to do it again in an ideal world.

 

[Henry_GyroLife]

Follow the maintenance manual Henry.

I have replaced the teeter bushings and teeter bolt on several Cavalons.

Lubricate them often and they will last longer.

Even with proper lubrication the bushings and bolt have a limited life.

I don’t remember what the schedule is; just follow the recommendations.

There are also specifications for the bolt wear although we always replaced it with the bushings.

If I put my finger on the bolt and rotor head and someone twisted the blade back and forth I could sometimes feel the play, sometimes not.

As I recall AutoGyro USA has a tool available.

We made our own.

Henry
I believe MTO tetter tower bushing is supposed to be replaced every 200 hours.
The problem with AG system is they are relying on the bushing and the teeter bolt to be the bearing surface. Averso has bearing in the teeter block and we use oilite bushings within the teeter tower. The bearing is the bearing and the bolt does not act like a bearing surface and can be tightened snug. Thus the bolt never has to be turned. In AG system every so often you have to rotate the teeter blt a quarter turn to make the bolt wear evenly.
In this kind of system it is next to impossible to keep the same rotor track and balance for a long time as even a thousands of a wear point will create a tracking issue. This does not occur with other systems using bearings. You should try changing the bushings. That may make things better. But ideally whenever you change the bushings or even whenever you rotate the teeter bolt you are getting away from your dynamic balance and have to do it again in an ideal world.

AutoGyro maintenance manual doesn't specify any hours to replace these bushings. I heard some replace them at annual inspection. I haven't changed mine for 470 hours. I can feel small pray when I twist my rotor head again the teeter bolt. I will replace them as soon as I get removing tools from AutoGyro. BTW, I noticed some performance degrading (climb rate as well as top speed) when I started having this problem.

 

[Abid]

AutoGyro maintenance manual doesn't specify any hours to replace these bushings. I heard some replace them at annual inspection. I haven't changed mine for 470 hours. I can feel small pray when I twist my rotor head again the teeter bolt. I will replace them as soon as I get removing tools from AutoGyro. BTW, I noticed some performance degrading (climb rate as well as top speed) when I started having this problem.

You should replace both the bushings and teeter bolt 200 hours. Your bolt is acting as the bearing surface just like trike’s Jesus bolt and we replace that every 200 hours also and it does not even teeter. Just pitch inputs from the pilot.

 

[Strike]

Enrico
Credo che la boccola della torretta MTO dovrebbe essere sostituita ogni 200 ore.
Il problema con il sistema AG è che fanno affidamento sulla boccola e sul bullone basculante come superficie di appoggio. Averso ha un cuscinetto nel blocco basculante e utilizziamo boccole in oilite all'interno della torre basculante. Il cuscinetto è il cuscinetto e il bullone non agisce come una superficie di appoggio e può essere serrato saldamente. Pertanto il bullone non deve mai essere girato. Nel sistema AG ogni tanto è necessario ruotare l'oscillazione di un quarto di giro per far usurare uniformemente il bullone.
In questo tipo di sistema è quasi impossibile mantenere la stessa traccia e lo stesso bilanciamento del rotore per un lungo periodo poiché anche migliaia di punti di usura creerebbero un problema di tracciamento. Ciò non si verifica con altri sistemi che utilizzano cuscinetti. Dovresti provare a cambiare le boccole. Ciò potrebbe migliorare le cose. Ma idealmente ogni volta che cambi le boccole o anche ogni volta che ruoti il bullone dell'altalena ti allontani dal tuo equilibrio dinamico e devi farlo di nuovo in un mondo ideale.

E Is this would be an ideal system for machines of this value? In 2023?🤔 I think there's something not working properly 😁 I think!!

 

[JAL]

I have AutoGyro NTO sport 2017 with rotor head sytem 3. The current hobbs read is 470 hours. I recently replaced sim washers for rotor and my cyclic has very small vibrations in a straight flight, but it getts more vibrations on take off, in turns and in vertical descending. Do I have to replace bushings on the rotor and rotor tower ? What hours should I replace these bushing normally ?

What are you calling sim washers?

 

[WaspAir]

Shim washers?

 

[JAL]

If the shim washers are the spacers on either side of the rotor that center the block between the towers, then this applies.

For AG they set spacer thickness in the factory for each rotor head during balancing as the rotor block might need to be slightly off center to be balanced. I think for most rotors both sides are generally equal but sometimes they are not, they can be few thousands in difference in thickness of each spacer which you may not notice by sight or even feel.

If you replaced the spacers with standard ones without measuring the originals, then your rotor head may not be centered on its mass and there is slight vibration as a result. Measure the thickness of the original ones if you still have them. The spacers are not under load so don't really need to be replaced very often, as others have mentioned replace the bushings and teeter bolt regularly. I replace mine every 100 hours or so.

I only found this out because after my first teeter bolt swap out the rotor was vibrating more and turned out that i didn't mark which side the spacers came from (assuming they were the same thickness) so my rotor was slightly out of center. I swapped the spacers around and it went back to normal.

If you do have the originals that you can measure, then get the new ones machined to the same thickness. Then there is 50/50 chance that you will install them on the wrong sides initially (if you don't know which side the originals come off) so if the rotor vibrates increases, then swap sides and it should then be close to your original vibration.

If you don't know what the spacers thickness were originally (you don't have them anymore) then you may have to go through a rotor balance, which is bit of pain. You need to get some new spacers that are maybe 5 thousand thinner than the current ones and 10 one thousand shims (you can make these out of coke cans or buy them). You put the thinner spacers on with 5 shims on each side. Go fly and feel the vibration, then move one shim to the other side, go flying if the vibration is worse than try the extra shim on the opposite side if the vibration improves then you know which side the extra shims need to be, continue moving the shims across until you find the smoothest rotor vibration. Now you know that the spacer thickness for each side is the spacer plus the number of shims. You may then want to get some new spacers machined to the appropriate thickness, so you are not having to thread the teeter bolt through the spacers and Shims each time you take it out, because that is real pain in the arse. Always mark which side the spacer comes from in any future Teet bolt removal (also which side the teeter bolt nut was on as well).