Prop Balance Graph

Walt · #1 03-29-2017, 07:59 PM

Just thought I'd post a quick view of another prop balance, this one on a RV14 with a new IO390 and Hartzell composite, as usual owner didn't notice any vibration but thought it would be good to check it while he was in the neighborhood.

Not sure if all the numbers will be visiable but the red circle represents the upper limit of 0.2 IPS. This one started off at 0.463 IPS (more than twice the upper limit) with a final result of 0.005 IPS on the 3rd run.

Do yourself and your equipment a favor, get er done.

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Norcalrv7 · #2 03-29-2017, 10:25 PM

Wow! Great results. Where are you mounting the weights? Starter ring gear or spinner back plate?

Walt · #3 03-30-2017, 06:33 AM

Quote:

Originally Posted by Norcalrv7

Wow! Great results. Where are you mounting the weights? Starter ring gear or spinner back plate?

I use the starter ring gear when available (like it is on our RV's) to avoiding having to drill holes in the spinner back plate plus it's also much easier than R&R the spinner multiple times.

The 0.005 this one ended up at is unusually low and should not be considered a "bench mark" for balancing. My typical goal is 0.05 IPS or less which is half the recommended after balance limit of 0.1 IPS.

I believe the 390 with its counterbalanced crank combined with the Hartzell composite prop contributed to the excellent results. The spectrum analysis also showed lower than average vib readings.

Noah · #4 03-30-2017, 10:15 AM

How do these readings change after greasing the prop - which is required annually? Each of several Zirc fittings requires 3 shots IIRC on my Hartzell CS prop, and occasionally air in the grease gun makes these shots inconsistent. Always wondered if this imbalance of grease affects prop balance. Have you ever balanced, greased, and measured the imbalance afterwards??

Walt · #5 03-30-2017, 12:56 PM

Quote:

Originally Posted by Noah

How do these readings change after greasing the prop - which is required annually? Each of several Zirc fittings requires 3 shots IIRC on my Hartzell CS prop, and occasionally air in the grease gun makes these shots inconsistent. Always wondered if this imbalance of grease affects prop balance. Have you ever balanced, greased, and measured the imbalance afterwards??

Nope can't say that I have, but I would suspect minimal changes as the grease is very near the centerline of the hub where weight changes have the least effect.

vic syracuse · #6 03-31-2017, 05:36 AM

I do a lot of prop balances as well and do not notice the grease making a difference. I think it tends to settle out evenly after the engine is run a bit.

Vic