And what was the cost please?
0.01 IPS is totally outstanding.
Having seen this done a number of times I find it incredible that such a figure could be achieved and was still there 5 minutes later 
What RPM was it done at?
I had dynamic prop balancing done a month ago, and we got to 0.06 IPS (at 2000 RPM). The last prop balancing had been done eight years ago. The mechanic took the weights off, and after everything was finished, he had to put them back on at the same position, except for one smaller weight at the opposite site. In other words, surprisingly, not much had changed in eight years. This explained why I did not notice any difference. Disappointing, since I expected some vibration improvement, but glad, since it suggests (I believe) no unreported prop strike in the last 8 years.
My last balancing also didn’t really change anything – as per the end of the report I posted earlier (at the end).
It doesn’t look like a small nick in the prop (for example) has much of an effect.
What I see so far seems to point to vibration issues being caused by stuff which may be unexpected. Some unintended coupling between the engine and the airframe has to be the biggest thing which one can do something about. For example if you have a hot air hose which is excessively tight. Or the exhaust pipe is touching the cowling where it passes through it (that was a problem on some TBs, I recall). Or the baffle seals have been done in a very stiff material, or done in a way which doesn’t allow them to slide (they are cut too narrow and just get wedged between the engine baffles and the cowling).
A new prop, especially a 3 blade one, can be terribly out of balance, but once you have taken care of that, the rest gets a lot harder.
Also I think a lot of it is subjective. I have flown with pilots who say their plane is smooth as a turbine but I could not see any difference to mine. That is why I started doing those vibration measurements, so I had an objective reference.
The biggest thing I discovered with those measurements is that the fundamental is insignificant. The main vibration components are harmonics, and the fact that the big one is a 6th harmonic
is just plain weird. The 3rd and 6th are nothing to do with any rotating parts.
Fenland – £250 + VAT. Two years ago MT quoted 300 Euros – other places are cheaper.
Peter – RPM 2280, planned on 2300 (cruising RPM), but the instrument decided it was happy with 2280.
I have slight vibration in the foot wells, this is not uncommon in RV’s as the exhaust is exiting just a few inches away.
Forgive my ignorance. But if you don’t feel any vibration in the aircraft, why would you get the prop balanced? Is it to stop long term damage from vibrations that you can’t feel? Or is there a requirement to do it every so often?
There is always vibration in aircraft
Loads of it.
There is an argument that it doesn’t do avionics much good so minimising it is a good idea.
Also, if it has never been done, it is worth doing because some planes are wildly out. Referring to Norman’s diagram above, my TB20 came from the factory at about 1.5 IPS. The vibration was very obvious even to me at the time – it felt really “sharp” and much worse than a PA28 I used to fly – and I refused to accept the aircraft. Eventually Socata climbed down and agreed to get it dynamically balanced. It cost about 200 quid and a flight to Exeter. Why was it so bad? Really crap QA at Hartzell was probably the start because a prop which is really accurately statically balanced (that’s all that a prop shop does) should not be that bad.
I am 100% certain that most vibration in SEPs cannot be eliminated, simply because it comes from the propeller airflow hitting the airframe. Try touching the windscreen during flight. It’s like holding a hammer drill, when drilling a hole in a wall.
Is there any update on this information?
My TB20’s Prop got attacked by some FOD (at Blackbushe or Redhill) and needs to be filed and then Balanced. The Prop was in very good condition unfortunately.
I am looking to get this done as quickly as possible.
Thanks.
Colin wrote:
My TB20’s Prop got attacked by some FOD (at Blackbushe or Redhill) and needs to be filed and then Balanced. The Prop was in very good condition unfortunately.
Can’t help with in the UK, although I do prop balances here in France.
That said, I doubt that any prop dressing will have a significant impact on the balance.
Would be interesting to make a balance run before AND after dressing the prop to see.
What is the process for correcting an imbalance on a prop? Is it simply a question of removing material from a blade tip?
