Dynamic Prop Balancing

[Jamie]

One important thing when balancing also is to find the right RPM you want to balance at. For example, I like to cruise at 2450 RPM, so that's where I ran up to on the ground with the balancer on the plane.

My vibration at that RPM? 0.01IPS. AWESOME! I didn't have to add any weights or anything. Needless to say when I got back home I pulled the spinner and marked the prop against the flywheel to make sure that I always align them the same way.

I always get comments from other pilots about the smoothness of my prop at cruise.

I have flown an $$$ MT $$$$ prop on my plane (of course we didn't balance it). The MT was definitely smoother during take-off but during cruise I think my Hartzell gave the MT a run for it's money in cruise flight. In fact, I believe my Hartzell was just a bit smoother (again, we didn't balance the MT).

[Finley Atherton]

Originally Posted by Webb

For those that are wondering how it is done.

A vibration sensor is bolted to top of the engine. Reflective tape placed on each prop blade in strategic locations. Now comes the part you can't do by yourself. YOU sit in the plane and do a static runnup to 2,400 rpm while the technician uses a strobe light in front of the plane.

You then shut it down, and the tech using bolts and washers adds weight to the starter ring.

Repeat until balanced.

Everything the same when mine was done, except I specified the rpm I was interested in and no one out the front and no strobe light.

Fin
9A

[RV7Guy]

WW 200 RV and ECI IO360. This balanced to a 0.00. The guy has never had a perfect balance before. Extremely smooth!! $150. He's based out of Falcon Field in Mesa AZ (KFFZ).

[steveKs.]

Jim Jeffries was at my home base balancing a AirTractor for a friend. I was visiting with him after I landed and he asked if I wanted my RV8 balanced and I told him it already had been dynamically balanced. He said he would check it and if he couldn't improve it I wouldn't owe him a cent.
I could almost see what was coming and boy was I wrong.
He checked it and said he couldn't improve it a bit, so I got a free check and a coffee cup.

Jim is a gentleman and honest. He travels to your site if you are interested his number is 985-507-9981. I just read it off my coffee cup.

[randylervold]

Originally Posted by Jamie

My vibration at that RPM? 0.01IPS. AWESOME! I didn't have to add any weights or anything. Needless to say when I got back home I pulled the spinner and marked the prop against the flywheel to make sure that I always align them the same way.

Jamie, if you ever remove your prop your balance solution is out the window. Just the few thousands of an inch that the prop can move on the bolts will change it so technically it needs to be rebalanced every time the prop is installed. I have not tested what the error range is for bolt slop placement only but it will be measurable.

[rvbuilder2002]

Originally Posted by randylervold

Jamie, if you ever remove your prop your balance solution is out the window. Just the few thousands of an inch that the prop can move on the bolts will change it so technically it needs to be rebalanced every time the prop is installed. I have not tested what the error range is for bolt slop placement only but it will be measurable.

Randy,
I also have never done a retest after the removal and (properly re-indexed) re-installation of a prop (so I can't say for sure) but I don't think it can move enough to make a measurable difference. The drive lugs on the prop flange are a pretty close fit in the counter bores of the prop hub.
What I have found with testing, is that there can be enough slop in the spinner mounting screws to allow the spinner to be positioned slightly different. I have seen this account for a .02-.03 IPS difference.

[randylervold]

Originally Posted by rvbuilder2002

Randy,
I also have never done a retest after the removal and (properly re-indexed) re-installation of a prop (so I can't say for sure) but I don't think it can move enough to make a measurable difference. The drive lugs on the prop flange are a pretty close fit in the counter bores of the prop hub.
What I have found with testing, is that there can be enough slop in the spinner mounting screws to allow the spinner to be positioned slightly different. I have seen this account for a .02-.03 IPS difference.

When I went through the DSS factory training they told us that remounting the prop in the same place would make a measureable difference though they didn't say how much. I haven't tested that though.

[bhester]

I just ordered my DynaVibe and will be providing Dynamic Balancing Service by the end of Sept.

I am based at KHVC Hopkinsville, KY and will do the work at my airport or yours. I plan on offering a group deal also.

If you've been thinking about getting yours done and live near my area let me know!

I'll let everyone know when I am ready to start.

I am a A&P mechanic and I purchased the unit with the calibration certification so I'll be able to do certified aircraft also.

[rvator51]

Another data point. We had to take our Sensenich prop off to do the S/B for the hollow crank pitting. After remounting it, we had the balance checked and it was still .02 so we left it alone.

[ronschreck]

Originally Posted by randylervold

When I went through the DSS factory training they told us that remounting the prop in the same place would make a measureable difference though they didn't say how much. I haven't tested that though.

When I had my Whirlwind 200RV inspected at 650 hours I asked if it needed to be re-balanced. According to them, NO.