H

Hansgiant

Member
Hello,

I have noticed a fairly pronounced vibration on landing my RV12. This happens on touchdown on the main wheels. I thought initially that I was touching down too fast but made a careful note of the speed the last time 50Kts. This only happens on tar or concrete strips not on grass or gravel.
Perhaps my tyres are a bit soft if so what is the correct tyre pressure that works?

Thanks for any advice offered.

HansGiant
RV12
ZU-FGV
 
The only time I experienced that type of noise and vibration it was because I inadvertently had a little brake applied. I am now careful to slip my feet well down to avoid the issue. In my opinion it is very easy to have a little brake applied if you aren't careful.
 
Ensure the wheels have been balanced. You can see and buy a simple balancing stand at Harbor Freight. I few months ago, I flipped the tires to even wear and did not re-balance them. On takeoff and landing had a good vibration just before liftoff and right after touchdown. Pulled the wheels, put them on the stand. They were way out of balance with the original weights. Removed the original weights and then added weights to balance both wheels. Vibration gone!
 
HansGiant (cool name),

I have not balanced my wheels, and have never noticed a wheel-related vibration. Probably just the luck of the draw, my tire/wheel combination happened to be well balanced.

If you are touching down at 50 you are not in the proper landing attitude. I do not teach that the stick should be all the way back. I prefer to have the student think of the landing attitude that should be achieved, which is nose high, holding the airplane just barely off the surface until you have dissipated all the excess airspeed, and the wings are just about ready to stall. This happens to work out to about 35 knots in the RV-12, but you should be concentrating on holding the proper attitude, not reading the gauges at that point. Once the mains are on the runway, keep the nose wheel off the ground by increasing back pressure until you can't hold it off any longer.

50 knots is a good over-the-fence speed, but touchdown should be much slower, and it will be if you hold the airplane off as long as you can. The payoff to slow touchdown speeds is less wear and tear on the gear and tires. and if wheels are at all out of balance, less vibration.

Hope this makes sense. Suggestion - find an instructor who flies tailwheel airplanes, do some practice landings with him/her.

John
 
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Marty, thanks for that link. Looks simple and the price is right. Even though I have not had any noticeable wheel vibration, I think that at next year's condition inspection I will reverse the tires and balance just on general principles.

John
 
Solution found! Yeah!

Thanks fellow RV'rs for all the input And advice.
The problem was the main gear wheel bearing was loose on one side. We found that the wheel itself had some lateral play. We removed the split pin and the castle nut from the axel, removed the wheel, checked and re-greased the roller bearing and put it all back together. We needed to tighten the castle nut a little more which sorted the lateral movement of the wheel, which now turns smoothly.
The aircraft has only got 124 hours on it but I guess the wheel bearings need a chance to settle, which is why a little tightening was necessary.

Happy:):):)
 
Hansgiant said:
The aircraft has only got 124 hours on it but I guess the wheel bearings need a chance to settle, which is why a little tightening was necessary.
Click to expand...

Or maybe the bearings weren't adjusted using the procedure recommended by Matco. It is in the documentation that comes with the wheels/braked kit.
 
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