Dynamic prop balance - worth it?

[Slick Nick]

I’ve got my prop coming off at annual here for a warranty re-seal (it was just overhauled last year and one of the blades started weeping.) I haven’t noticed much in the way of adverse vibrations thus far, but is the cost of a dynamic balancing worth it when the prop is reinstalled? I typically run at either 2500 or 2400 rpm depending on if I’m doing a best power or Econ cruise. If I get it balanced to a specific RPM, say 2500, will that make a noticeable difference when I choose to run 2400? 

I fly a lot, and as I mentioned I haven’t really noticed much vibration as it is, but if it’s something I’m missing out on I’d definitely go for it. A smoother running engine is good for longevity. 

Would love to hear some feedback, good or bad, if it’s worth it. McCauley C214 2 blade on a ‘91 J model. 

[mike_elliott]

yes

[Hank]

Yes, dynamic balancing is worthwhile. 

[Pinecone]

Another yes.

Vibration is bad for most components and actually the airframe itself.

[Paul Thomas]

Lower RPM have higher amplitudes. 

[MikeOH]

Yes.

[EricJ]

A buddy was having one of our local prop balancing guys do his airplane, so while he was here I had him do mine, even though I didn't really have any complaints.    He said mine was pretty good to start with, but he did manage to get it better.   On his instruments it wasn't a huge change (I don't remember the numbers), but it was a difference.   Interestingly, even that small change was noticeable in the airplane.   It really did make a noticeable difference, which I thought was pretty cool.

[FlyingDude]

Yes, I do dynamic balancing (as an a&p) and every single one of my customers said they could feel the difference. 

[dkkim73]

Any opinions on rebalancing after changing cylinders? (3 since balancing after prop overhaul)

[GeeBee]

23 minutes ago, dkkim73 said:

Any opinions on rebalancing after changing cylinders? (3 since balancing after prop overhaul)

Yes, do it. I just had mine done last Friday. I usually do it every 3 years or 500 hours whichever occurs first. I was talking with the shop about changes that require re-balance and changing cylinders is one of them.

[Bolter]

(on my former J) I also thought nothing of my vibration levels, but was convinced by my A&P to let him do it.  Sure enough, it was a seat of the pants measurable difference, for all of my typical operating speeds.  I do not think that balancing for 2500 rpm means that 2600 and 2400 rpm will be rough as a trade off.

I do not think I have heard anyone complain that balancing did not make an improvment.  

[Hank]

1 hour ago, GeeBee said:

Yes, do it. I just had mine done last Friday. I usually do it every 3 years or 500 hours whichever occurs first. I was talking with the shop about changes that require re-balance and changing cylinders is one of them.

What is your rationale for this? 

I had mine checked at annual in 2018, having been done during overhaul by the previous owner around 2003-04. It was still under 0.01 ops. Haven't checked it since.

[GeeBee]

1 hour ago, Hank said:

What is your rationale for this? 

I had mine checked at annual in 2018, having been done during overhaul by the previous owner around 2003-04. It was still under 0.01 ops. Haven't checked it since.

Prop blades erode, sometimes you have to dress out nicks and if you have de-ice boots so do they. Mine did not change much but it did change. 

[Slick Nick]

Thanks everyone for the input! I’ll be getting it done 

[TaildraggerPilot]

It’s worth every penny, as long as the pennies don’t add up to more than $425

[hubcap]

Definitely worth it in my opinion. I noticed the biggest difference in cruise, not so much in the pattern or climb. 

[jager3]

I’ve been involved in blade balancing aircraft since the “mid ‘70’s on everything from big helicopters to my own Mooney. It extends component times and provides a smoother flight in most aircraft configurations. My Mooney’s 0-360 Lyc was never the “smoothest” running engine ever designed; dynamic prop balance is about the cheapest way to extend TBO of your components IMHO.

[philiplane]

On 8/25/2025 at 10:10 AM, Slick Nick said:

I typically run at either 2500 or 2400 rpm depending on if I’m doing a best power or Econ cruise. If I get it balanced to a specific RPM, say 2500, will that make a noticeable difference when I choose to run 2400? 
 

It's recommended to balance a prop (and the engine too, by default) at the commonly used cruise RPM. Only because that is where the engine spends most of its time.

Whether that is 2400 or 2500 rpm, makes little difference. 

[Justin Schmidt]

Am i the only on that does 2350 or 2300 lol

[Hank]

8 hours ago, Justin Schmidt said:

Am i the only on that does 2350 or 2300 lol

I vary RPM by altitude:

• Up to ~3500 or so, 23/2300
• 4000-7000, 22/2400
• 7500 & up, WOT-/2500

It greatly simplifies ATC step-climbs and descents, as well as approach entries.

[Slick Nick]

Update:

Put a couple of hours on the airplane since annual. I had the prop rebuilt with new bearings and to replace some leaky seals, and figured I'd have it dynamically balanced once it was reinstalled. Before balancing, the prop checked out at 0.25ips. Its important to note that I don't know if it was that bad before the prop rebuilt, but that was the starting point, which is pretty terrible. After 6 iterations, they got it down to 0.05ips at 2500 RPM. They attempted to get it dialed in even further, but wound up just chasing the same amount around the plot. I am happy with 0.05ips. 

After flying the airplane, I can confirm a VERY noticeable difference in vibration. Especially now when transitioning through the "forbidden range" on short final, the glareshield doesn't vibrate nearly as bad as it used to. I was charged 4 hours labor. I tried several cruise RPM's yesterday, and everything from 2700 down to 2200 is smooth as silk. 

For anyone else considering a balance, it's well worth it. 

[jeremyc209]

I post this another forum but thought it would get more exposure here. 

Just got my prop balanced and oil changed when my plane was in for avionics next door.

Started at 0.20 IPS @ 2400rpm

Ended at 0.01

I'll upload the sheet if anyone wants to see it. Added 9ish grams in one place. 

Question: Oddly enough, after my first flight my prop stopped in different position, 2 and 8 o'clock. After my test run up a couple weeks ago (the fog has been killer here) it stopped at the normal 10 and 4 position. I don't remember it ever stopping like that before but I've only owned it since February. I always push it backwards the same way so I would have noticed the prop stopping in a different position before.

Do your props always stop in the same spot without fail or is the occasional odd stop normal?

[Hank]

10 hours ago, jeremyc209 said:

Do your props always stop in the same spot without fail or is the occasional odd stop normal?

There is some variation where my prop stops. It's a 3-blade, and to use the tow bar, I need 2 blades down and one up, but occasionally it stops with one down, right in front of the nose gear leg.

[wombat]

How many bolts hold the prop on the flange, and are they always re-clocked to the same position when re-installing?   I thought there were 6 bolts, so if they remove and re-install in a different orientation, you could be off by 1/6, 1/3, 1/2, 2/3, or 5/6 of a rotation, or be exactly where you were before.

[Slick Nick]

2 hours ago, wombat said:

How many bolts hold the prop on the flange, and are they always re-clocked to the same position when re-installing?   I thought there were 6 bolts, so if they remove and re-install in a different orientation, you could be off by 1/6, 1/3, 1/2, 2/3, or 5/6 of a rotation, or be exactly where you were before.

I think on my engine there is a locating dowel on the flange so the prop can only go on one way?