Dymamic Prop Balance

[WAFI]

I got my prop dynamically balanced yesterday by Aircraft Propeller Works who met me at KORL on a Sunday morning. Very nice guy and with a few run ups and some weight got it from .33 down to .04 and I can't complain with that number.

Most peoples first question seems to be "Well can you feel a difference?" my answer to that is yes but it is not a dramatic difference, just a noticeable one.  Maybe just a placebo...

The real difference is piece of mind that I know where I stand now and that I'm not causing excessive wear on my engine internals.  

[slowflyin]

I can tell the difference when I lay my phone on the glare shield and it's still there an hour or two later.  

[A64Pilot]

.33 IPS is quite high, it’s actually an acceleration measurement in inches per second. Pretty much everything from helicopter rotor systems to propellors .20 has been considered the max forever, and with the old strobe light balancers it was a good limit as they required a lot of interpretation and use of printed charts and many couldn’t get a stable “clock angle” below about .10.

‘But modern balancers can do much better, but it’s not just the engine, it’s avionics that last much longer not being shook to death and even the airframe itself, fewer “working” rivets etc. 

[WAFI]

@A64Pilot ‘But modern balancers can do much better, but it’s not just the engine, it’s avionics that last much longer not being shook to death and even the airframe itself, fewer “working” rivets etc. 

Agreed... I think this will become an annual thing for me. I might actually go ahead an buy a DynaVibe for the next time. I have a few people that would love to have access to one for a nominal donation. Its a pretty simple procedure now with the new tech spitting out the solutions.

[A64Pilot]

Once balanced it shouldn’t change much, even filing a prop should make very little difference.

Now R&R a prop to change an alternator belt I’ve seen change balance, which you wouldn’t think it would, but it did

[Hank]

  On 10/11/2022 at 3:14 PM, A64Pilot said:

Once balanced it shouldn’t change much, even filing a prop should make very little difference.

Now R&R a prop to change an alternator belt I’ve seen change balance, which you wouldn’t think it would, but it did

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It must have been re-indexed when put back on. Like 180º different for a two-blade, which will certainly change things!

[WAFI]

  On 10/11/2022 at 3:14 PM, A64Pilot said:

Once balanced it shouldn’t change much, even filing a prop should make very little difference.

Now R&R a prop to change an alternator belt I’ve seen change balance, which you wouldn’t think it would, but it did

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The guy that did mine said that as little as uneven torquing on the bolts could change the balance or if the spinner was 180 out would throw it off.

[Hank]

  On 10/12/2022 at 4:33 PM, WAFI said:

The guy that did mine said that as little as uneven torquing on the bolts could change the balance or if the spinner was 180 out would throw it off.

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My (3-blade) spinner and blades are numbered for realignment [sharpie on the inside of the spinner and root of the blades]. The little pieces that screw on behind the blades are also numbered. Helps keep the balance job correct--it was balanced to 0.01 around 2004/05 before I bought it, so I had it checked during annual in 2018, still good.  

[Pinecone]

This is something I would like to have done.  Need to find someone in the mid-Atlantic area.

[A64Pilot]

  On 10/11/2022 at 5:03 PM, Hank said:

It must have been re-indexed when put back on. Like 180º different for a two-blade, which will certainly change things!

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You know it wasn’t but there was enough movement in something to make a difference, it doesn’t take much

 

[carusoam]

  On 10/12/2022 at 7:14 PM, Pinecone said:

This is something I would like to have done.  Need to find someone in the mid-Atlantic area.

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See if sensenich in PA, next to the MSC…

Well…. If you can figure this one out…. 

Best regards,

-a-

[Browncbr1]

I have a prop balancer.    Most of the time, an un-balanced prop starts out around .2-.4.   Usually, after balancing down to .00-.02, a few knots are gained.   Also, less pilot fatigue.  

[A64Pilot]

If you can get down to .0 anything your good, .02 is 1/10 the max allowable for just about all helicopter rotors and also is usually given for props too.

Not too long ago we used strobe lights and of course a strip of reflective tape and read a “clock” angle, then went into paper charts and intersected clock angle and IPS and read how much weight and again angle, installed weight and ran it again and hoped it got better. It was difficult with the old equipment to get a stable clock angle below about .1 IPS so it became more of an educated guess at that point.

Modern equipment took all the skill out of it, but is so much better.

We are balancing the prop of course, but in reality the whole rotating assembly has an effect, I’ve seen some that just wouldn’t balance as in the .1 vibe would move around, but you couldn’t get it any lower be engine mounts. Anything loose can have an effect, if you get one that just won’t balance start looking for sagging mounts or something loose like a muffler.

You would think spinners would be made so that they can only go on one way, but they aren’t. I used to index spinners by drilling a small, about .020 hole in the spinner and the backing plate between screws, sharpie is fine if you don’t forget but does wear off, the small hole isn’t really noticeable and doesn’t wear off.

[Jim Peace]

Did you have to do any of the work?  He took the cowl off and all the engine shrouding?

how long did it take? 
cost?

I just got my prop overhauled and was wondering about getting it balanced.  I am based at the creek. 

[KSMooniac]

I would wait a few hours at a minimum and let the prop run in a bit before getting it dynamically balanced. It is definitely worth it.

Sent from my LM-V600 using Tapatalk

[skykrawler]

  On 10/12/2022 at 7:14 PM, Pinecone said:

This is something I would like to have done.  Need to find someone in the mid-Atlantic area.

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H&H Propeller with TRIAD at Burlington, NC can do it.

[Pinecone]

Thanks.

I talked to Sensenich, they are a bit over $400.

[201er]

  On 10/12/2022 at 7:14 PM, Pinecone said:

This is something I would like to have done.  Need to find someone in the mid-Atlantic area.

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Byron does it for $300

In theory it was a big improvement. Down from 0.50. In reality it’s subtle but noticeable. But I’m sure in the long run it’s worth having less things shaking.

 

[EricJ]

I'd been helping a buddy with an engine swap on an experimental airplane and it got to the point where it was ready for prop balancing.    He found a guy that mostly does experimentals (I think he's not an A&P), so I figured I'd take the opportunity while he was there to do mine as well.   I supervised and signed it off.

On the TIO-540 with freshly-refurbished Hartzell composite 3-blade it started about 0.34 IPS and finished at 0.01 IPS.   The balance guy said most airplanes typically start at around 0.3 or so, and "bad" ones are around 0.5.

My Hartzell manual says 0.2 or less is good enough, and this guy guaranteed 0.07 or he only charges his setup fee of ~$50 or so.

Mine started at 0.17 and ended at 0.02, which he said was about as good as you can practically expect with a four cylinder.   It is noticeably smoother, enough to definitely make long flights nicer, but since mine wasn't awful to start with it's not a dramatic difference.    He recommended having balancing done once a year to keep up with normal wear/etc on the prop, engine, etc.    Afterward I figured I probably should have cleaned the bugs off the blades first, but, oh, well...

 

[Hank]

My prop was balanced after installation by the previous owner in 2003. At annual in 2017, I had it checked, just because it had been so long. It was still at 0.01, so just the $50 set up fee for my peace of mind.

3 blade Hartzell, O--360.

[EricJ]

  On 11/5/2022 at 7:46 PM, Hank said:

My prop was balanced after installation by the previous owner in 2003. At annual in 2017, I had it checked, just because it had been so long. It was still at 0.01, so just the $50 set up fee for my peace of mind.

3 blade Hartzell, O--360.

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Kudos to everybody who properly indexed and clocked the spinner and the prop and the backing plate and the flywheel over all that time!

[Hank]

  On 11/5/2022 at 8:37 PM, EricJ said:

Kudos to everybody who properly indexed and clocked the spinner and the prop and the backing plate and the flywheel over all that time!

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As far as I know, the prop has only been off one time (since I bought her in '07). The blades, spinner openings and cover plates are all numbered, and until my IA retired 3 years ago, I did owner assisted annuals, so all covers and plates on the entire plane were removed and reinstalled by me . . . .

[Browncbr1]

Recently did a fellow MSer who visited here.   The doghouse takes a bit of extra time and it would have been nice to have had the time to fabricate a different bracket to get further forward on the case halves.  The engine was circa 1989, so not sure if the isolators were original or not, but we were getting too much erroneous data below about .03-.02, so we stopped there.  He reported a smoother ride home, but no discernible increase on tas this time.  
 

[carusoam]

Nice details shared gents!

Mooney fly-in at Byron’s one week end…?

Best regards,

-a-

[Pinecone]

My plane is going to Byron for Annual soon.

Depending on if there are any other significant issues, I will have him do this while it is there.