Dynamic Balancing in FL/Southern GA

[Hang 4]

Looking for recommendations for a Dynamic Balance in the South East. My on field AP doesn't do it and I've had a tough time finding someone good to do it. One thing I'm looking for is using the holes in the Lycoming flywheel for the weights vs drilling into the spinner backplate.
I had a cylinder go bad and with the new one in, there is a definite vibration that was not there before.
Any thoughts?

 

[Bell206]

I had a cylinder go bad and with the new one in, there is a definite vibration that was not there before.

To clarify, this is a new vibration after the cylinder change or did an existing vib get worse?
Is the vib noticeable at all RPMs or just a specific RPM or range?
Does the vibration frequency and/or amplitude change with RPM or stay the same?
Did you use the same piston, piston pin, pin plugs with the new cylinder, or was it all changed?
Was anything else removed during the cylinder change?

 

[Gary Ward]

Wonder if they weighed the new parts and compared to the old parts? Was the prop removed during the change?

 

[Bell206]

they weighed the new parts and compared to the old parts?

FYI: Lycoming uses a part number coding system to indicate weight ranges for certain parts like connecting rods, pistons, piston pins and plugs. I haven't checked on it in years but for those items needing individual field replacement one needed to get a part with an "S" suffix which fit into a narrow weight range. So actual weighing should technically not be needed. An engine spectrum check will find it though.

 

[Hang 4]

Can't answer those questions right now, AP closed and that level of detail wasn't logged. Having said that, I had a broken ring for an undetermined amount of time. The new cylinder has changed the power profile a lot and I had a balance done when that cylinder was making less power. Pretty sure that's the difference and it's not a very big vibration, just enough that I know it's an issue.

Repeating my original question, what's a go-to place in the SE to get it balanced?

 

[Bell206]

The new cylinder has changed the power profile a lot and I had a balance done when that cylinder was making less power.

Don't have any suggestions for a balance provider, but just be sure to not mask an existing problem with a new balance. It can happen. Good luck.

 

[mondtster]

Heed Bell’s warning about masking the real problem. I’ve been there before, and it can sometimes be difficult to unravel the story once you start changing things trying to make it better.

In my opinion, I don’t think a cylinder change due to a broken ring should cause that much change. I’d be looking at what got changed at that point before I’d try to fix it with a balanced.

 

[donjohnston]

Looking for recommendations for a Dynamic Balance in the South East.
Any thoughts?

Sunset Eagle in Panama City (KECP) does dynamic balancing.

 

[unsafervguy]

saint aviation at x35 does them i believe. give jesse a call

 

[Hang 4]

I appreciate the comments about the possibility of the new cylinder causing the vibration. I'll mention the vibration and double check what got replaced on Monday when the shop is open. Having said that, I'm pretty comfortable that the additional power that cylinder is making is most of the issue. I had the prop balanced about a year ago and I'm pretty sure the ring was broken then. The CHT difference (now lower) in the old cylinders after the replacement is dramatic. They were making up for the "lazy" cylinder for quite a while. Also, the vibration I have now is not that bad, just a bit more than what I'm used to. Lastly, the last balance I had was not that great and expensive, so looking for a new source.

An engine spectrum check will find it though.

@Bell206 One of the things I was looking for was what I think you are describing as an engine spectrum check. If I recall, it uses a second sensor to find the source of vibration beyond just the prop and flywheel? There seems to be a bit of difference between AP's that have a dynamic balancer and those that can really understand what's going on in the whole powertrain. That was part of what I was looking for.

 

[Bell206]

There seems to be a bit of difference between AP's that have a dynamic balancer and those that can really understand what's going on in the whole powertrain.

Maybe. From my experience, a number of mechanics only have equipment that can balance props. It takes additional functions and software to perform spectrums with the equipment costs usually north of $3000 vs the $1500 for prop only. And yes it takes a 2nd velometer at the rear of the engine in addition to the original velometer at the front. With this set up and the required software you can check across the entire spectrum of frequencies in the engine. Plus there's the knowledge required to perform the spectrum tests as well.

Perhaps give some area engine shops a call and see if they can run a spectrum and balance your prop all at the same time. It was an option I had offered. But just to reiterate, vibration is not technically a function of engine power. Out of curiosity, why did you have the previous balance performed? Was it routine in nature, or did you have similar vibration as this one?

 

[Hang 4]

Perhaps give some area engine shops a call and see if they can run a spectrum and balance your prop all at the same time. It was an option I had offered. But just to reiterate, vibration is not technically a function of engine power. Out of curiosity, why did you have the previous balance performed? Was it routine in nature, or did you have similar vibration as this one?

Thanks - the previous balance was after a prop overhaul. (fixed pitch). Full history, I've had the plane about 5 years. Got one done about 4 years ago in ATL. Difference was dramatic for the better. Had a prop overhaul as part of an annual two years ago. Had some minor vibration and had a second balance done. Wasn't thrilled with this outfit. Didn't have the same good effect as the prior one. The prop has some normal tip wear and I like to do a dynamic balance every couple of years. I moved from ATL to Northeast FL and have a great AP/IA on my home field of KFIN. He doesn't do balances so I'm on the hunt for another place and looking for someone that is really gifted at it vs just has a balancer.