Vibration in the nose wheel

[zhoser]

Hello

 

My name is Carlos and I write from Madrid (Spain). I have just bought a second hand Savannah Xl with a rotax 912 ULS and tundra tires. I am very happy with the plane except for a problem in the nose wheel.

 

When I land the plane the nose wheel vibrates a lot and the noise and vibration are very noticeable. I always try to hold the nose wheel most of the time in the air holding back the stick until its limit to prevent it. When I do it very well it vibrates very little, but if I relax a little and the nose wheel touch the ground with a little speed (with 50 km/h) it starts to vibrate a lot and I think this is not normal.

 

I spoke with Spanish ICP dealer and they told me it is normal, and I don’t have to concern about it, but I spoke with some Savannah Xl owners in Spain and they told me they don´t have this problem, maybe from time to time the nose wheel can vibrate a little if you land very fast but not so much how I described to them.

 

I´ve had different planes in my life but I never had a vibration like this in any plane. And in the other hand landings are not comfortable thinking all time to prevent this vibration. I can´t believe this be a design mistake and I think I have some problem in the nose wheel.

 

I noticed when I move the nose fork it has a big play (left-right) and even the screws touch the nose tire leaving a mark in the tire.

 

Some pilots told me I could reinforce the nose fork to prevent this but I am not sure to do this modification without to know if this is normal or what is the problem.

 

¿Do you know if this is normal or not?, ¿what should I check? ¿Is there any solution to prevent this situation?. I like very much the plane but this vibration is getting in a problem.

 

I would appreciate a lot your advices.

 

Regards

 

Carlos

 

 

[Skee]

Is the plastic plate in the lower support bad? the one clamped between two plates?

 

 

There is also a upgrade for it.

 

 

Is the wheel bearings bad?

 

What is your Tire pressure?

 

 

[rick morawski]

Hi Carlos

 

I think it would be the tyre is out of balance. The "tundra" tyre is really a golf cart tyre and they don't bother with balance issues when manufacturing because they only go slow. When they are put on an aircraft where they go fast then balance issue can show up.

 

You could swap the tyre with one of the mains or get a new one but still no guarantee it will be balanced. I read where one guy tried five tyres before he got one that was good enough.

 

Cheers

 

Rick

 

 

[Kyle Communications]

Also check that your wheel bearings are tight on the nose wheel shaft

 

 

[zhoser]

Thank you for your quick answers. I am going to check all you told me.

 

¿What is the correct tire pressure for these tundra tires? ¿ is it possible to get another tundra tires better than these golf cart tires? ¿ Where can I get the upgrade you showed me?

 

Regards

 

Carlos

 

 

[Skee]

ICP has the upgrade and tire pressure should be 0,8 bar i think..

 

If you have the Cash and want premium tires and wheels you can buy the Beringer wheels/tires, awsome quality.

 

http://www.beringer-aero.com/

 

i did, but Premier cost allot,

 

 

 

 

 

[erd72]

I had the same problem,

 

- Put the sav on the tail slider, normally if your plan is balance it will stay like that

 

- Deflate the tyres and make a "massage" of the tyre to be sure that the tube is at the right place then reflate at 0.8 b if you can make a balance of the complete wheel

 

- Check the bearings wheel

 

- Check the upper fitting of the suspension arm (if you have too much gap it can also come from some cracks in the firewall)

 

- Check the sliding of the suspension arm, the gap is less than 1 mm. You can reduce bu de / re sassembly of the plate.

 

-Check also the fitting bolts and nuts of the fork

 

If you don't need bush tyres, you can also use another tyre like 6x6 airtrac

 

I hope it could help you.

 

 

[zhoser]

Thank you for the information. I will check all you told me.

 

 

[Ultralights]

the bolt heads should't hit the tyre at all. if they are, the tyre is to tall for the axel location. usually when installing bigger tundra type tyres, the axel has to be moved down a few centimetres.

 

 

[Russ]

I was surprised just how far out of balance my nose wheel was.....lots

 

 

[mcrowley]

One simple trick to balance a tire can be borrowed from motorcycle riders. Put about 4 ounces of dynabeads in the tube after temporarily removing the valve stem, then simply air it back up. It works perfectly on the large rear tire on my Honda Goldwing.