Jump to content
2018 Page Fly-in Cancelled! Read more... ×
207WF

dynamic prop balance?

Recommended Posts

Yes, and it was moderately out of balance. I don't remember the original reading... I think it was around .4 to .5 ips. I got it down to .02.

 

Flew for a few hundred hours, nice thing was that the exhaust stopped cracking all the damn time.

Share this post


Link to post
Share on other sites

I had my CT's prop balanced.  The prop wasn't that far out but it was enough to warrant having this done.  This improves cabin comfort but the important things is prop vibration can be detrimental to engine components - as Corey points out with his remarks about exhaust cracks.  Air frame components might also be affected by vibrations which originate at the prop if these vibrations are not attenuated by the engine mounts.  There's a good article on prop balancing in this month's EAA Sport Aviation mag. 

Share this post


Link to post
Share on other sites

Had mine done.  Big difference in felt vibration.  Mine was pretty bad out, near the limits...it went from 0.6 to 0.05.

Hi , what is the meaning of 0.6 to 0.05 

how do do you gauge it ?

can you do the balancing by your self ?

thaks.. 

Share this post


Link to post
Share on other sites

You have to use specialized equipment to dynamic balance a prop. They cost thousands.

 

Those measurements are in inches per second (but since it's supposed to be acceleration, it should actually be inches per second per second).

Share this post


Link to post
Share on other sites

Thanks for the reply.

My ctls is 2009 model and on 545 h. I have a vibration problem for the last 40-50 h.

 

We checked for the carb sync. But it was ok. I noticed that propeller's blades are tracking in different paths. Not cycling on the same path.1-3 cm distance between two paths.

 

when the engine is cold and when it s on low rpm there is a big vibration. on hi rpm s it looks normal.

 

I am using a neuform 3 blade propeller.

What do i have to do? 

Share this post


Link to post
Share on other sites

There is no damage on the blades :(

 

You should check tracking by hand, rotating slowly, preferably with plugs off.

 

If you still see the abnormal tracing, you need to take apart the prop. 1-3cm is HUGE and extremely abnormal. SOMETHING is wrong. Check to make sure the hub isn't damaged, or that the prop isn't separating from the flange, and make sure the blade angles are set correctly.

Share this post


Link to post
Share on other sites

Our local A & P is getting a dynamic balancer.

 

I think he said $275 or thereabouts for a balance. $75 if the machine shows the prop "close enough".

 

I'm thinking about getting it done.

Share this post


Link to post
Share on other sites

Is it possible that blade angels will change by them self?

 

if one of the blade s angle is higher than the others , it will track in a front line from the others. And this can cause a vibration..

 

on high rpm s it is all normal.

 

I dont know what to do? do you think , do i have to send them back to neuform to check for the balance?

 

someone told me that there is a soft material inside the blades. by the time they can change the balance and they have to be checked by the producter.

 

I am confused :(

Share this post


Link to post
Share on other sites

I can't give a lot of advice without seeing it myself. If you're saying the track is 1-3cm off, then you NEED To check it.

 

Yes, the blades can move on their own, especially if the bolt torque hasn't been checked in a long time. Vibration can loosen bolts. If that 1-3cm variation is caused by blade angle variation, then those blades will be noticeably off.

 

Regardless of the cause, you really should take a close look at the prop hub, blades, etc. I've only seen damaged blades track this far off.

 

Are you checking track in this manner?

 

Share this post


Link to post
Share on other sites

thank you a lot... this will help me a lot. and it is easy to do.

 

1-3 cm tracking mistake is when the engine is running in 2500-3000 rpm. when you turn it by hand slowly you it much more less.

 

I think that if one of the blades attack angle is higher than the other , it will try to track in a fronter line from the others. and this will cause vibration.

 

thanks a lot agian. this weekend i will go to hangar to check it again like this method and i will share my experiences.

 

nice to meet you ..

 

mehmet

Share this post


Link to post
Share on other sites

thank you a lot... this will help me a lot. and it is easy to do.

 

1-3 cm tracking mistake is when the engine is running in 2500-3000 rpm. when you turn it by hand slowly you it much more less.

 

I think that if one of the blades attack angle is higher than the other , it will try to track in a fronter line from the others. and this will cause vibration.

 

thanks a lot agian. this weekend i will go to hangar to check it again like this method and i will share my experiences.

 

nice to meet you ..

 

mehmet

Ah OK, then you don't have to worry if it's pretty close. You don't want to check blade tracking on a prop while the engine is running because the tail movement is significant (helis are checked while running though!). You can use an angle gauge or prop protractor to correct the blade, but it is absolutely critical that you use a careful, deliberate, and precise process to set it. You need to use a common point on the airplane itself to set the blades, as even rotating and mucking about with the blades will shift it around a little.

 

I often use the hub as my calibration point, and I re-zero after each reading or adjustment. I aim for no more than 1/10th of a degree variation between all of them.

 

As you torque the bolts, the angle will change. Tighten a little at a time and recheck. Once you get around half torque, they won't shift much anymore.

Share this post


Link to post
Share on other sites

thanks .  I will do it with a tecnician. It s little bit much for me for the first time :)

 

I dont have the neuforms adjustment tool. but tecnicians in turkey make tools for them self. 

 

if one blade is in an different angle to the others , I will only adjust that one and wont touch the other blades.

 

is that correct ? or do I have to set all of them from the zero ?

Share this post


Link to post
Share on other sites

Just make sure they all match, and you get the correct RPM. You can use an angle gauge or prop protractor. It's actually quite commonly known how to do it.

 

You should first determine if your RPM is correct for in flight WOT, and if so, record what your ground static RPM at WOT and check after adjustment. If you have one blade way off, you will end up adjusting all of them.

 

Once that is done, do a runup, and recheck torque. You can do a dynamic balance now. Then after that, say around 25 hrs, recheck and retorque to make sure it hasn't moved.

 

When you change blade angles at all, your dynamic balance is invalidated and have to do it again.

Share this post


Link to post
Share on other sites

Where and what did you guys use to add weight?

 

I add a little paint to the band at the blade tip .

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×