Opinions on Dynamic Prop balance rpm

[N3322G]

[MULEFLY]

[Dale Vandever]

Pat, we had a few fly-ins in Burnet years ago and an old gentleman, with many years of experience in prop balancing, would fly in from San Antonio and balance props.

He always asked "what rpm do you use in your normal flying?"

He then advised that you run the engine at that rpm while he did the balancing, because that would give you the most benefit.

His success ratio was very high.

Dale

[Mike Foster]

That's how the gentleman that comes to our 'drome does it. Everyone seems happy.

Mike

[N3322G]

Thanks for all the replies. It makes perfect sense to me but as i looked at various materials and websites, 2000 kept coming up and that didn't make sense to me as most Comanche folks I know fly 24 square.

Again, thanks.
Pat

[ics-12766]

My shop will balance where I want... cruise RPM is it

I run the engine for 'em.

[N3322G]

And the results were excellent at Meacham field in Ft Worth

Started .14 IPS left and .14 IPS right
both are within spec

as long as the cowls were already off and the wind was nearly calm...

Ended with .04 IPS left and .03 IPS right

One interesting thing was the A&P tech was ready to mount the weights by drilling through the backplate. At my direction he mounted a heavier weight in the Hartzell provided locations and the results were excellent as shown above. I had wanted to use the on airport prop balancer at 52F but he uses the ACES system which is designed to put weights on the backplate screws that attach the spinner. Even though I have the reinforced backplate, having lost spinners in flight in the past because the backplate broke at those screw locations, I really didn't want to potentially cause a problem in the future so I went to a shop that uses Hartzell weights.

and the owner came out to say the IPS for the engine shows a very smooth running set of engines - compliments of Charlie Melot's shop Zephyr.

BTW for those who know the history, I had the lord mounts' torques checked at annual - they were good. Smile.

Happy Ending.

[Dave Fitzgerald]

[howard]

Mine is balanced with some nuts and bolts on the starter ring gear . It is a much heavier piece of equipment. It will not likely crack.
That is the way my shop does this job.
Howard

[Zach Grant L1011jock]

Dave,
Balancing with the holes in the ring gear is the prefered method. The hartzell weight locations do not allow for much flexibility in positioning of the weights. As Pat is proof, it can be done, but more likely than not, it will be unsuccessful with most engines. BTW, this is how engines are dynamically and statically balanced by the overhaul shops. Note the milled large holes in the ring gear, and some that are only partially through the plate. Some ring gear plates have no big holes, other have 3-4. Balancing an engine (which is what you are doing here, the prop and all the rotating components the prop is bolted to work together) with a prop on a long extension, excessive stresses can be introduced to the crank flange if too much weight is needed. Having the weight centrally locatd closer to a main bearing decreases bending moments.
-Zach

[8266Y]

I just had mine balanced at H & H Propeller at BUY.

The left and right were both OVER 1.0.

As they were doing it, I could hear the pitch change as they were adding weights to them.

After they were done, both the left and right were .01!

On the flight back, it was like the props were not on the plane it was so smooth.

Incase anyone is thinking about it, it is money very well spent!!!

[Zach Grant L1011jock]

Randy,
Glad you had a great experience with this. A reminder for all, this needs to be done anytime any work is done on the props, even something as minor as dressing the leading edge, otherwise you are out of ballance again. Would you rotate your car tires without rebalancing?
-Zach.

[Mike Day]

What is the going rate on Balancing? Where did you get yours balanced last Zach? Nice seeing you last week!!

[Zach Grant L1011jock]

Mike,
Not really sure what the rate is these days, but it has been between 100 and 150 bucks per engine in the past. I have a friend in Indy who is actually the regional tech rep for American Eurocopter, and he does them for me. Really knows his stuff and makes the engines turbine smooth when done. If you are interested let me know and I will hook you up with him.
-Zach

[8266Y]