The key point that this thread is about is a vibration that is NOT "normal". The key indicator is a change in the magnitude of the vibration with a change in RPM. There are enough of you out there that have responded to me directly that state you have made all attempts at correcting the "normal" vibration issues, ruling out alternators, cowl interference, motor mounts, dynamic balancing, crank counter weights, etc. Those things are normal and would not likely cause damage to the crank prop flange if left untreated. The problem we are discussing is related to the prop/engine combination.
We have confirmed reports of 550 motors being smooth with McCauley props, Aerocomposite Props and MT props, to answer Charley's question below. However, NO ONE has come forward and said "My 550 engine/Hartzell Scimitar 78" prop combination is smooth". I would be very interested if someone out there can say that. To the contrary, I have received multiple responses from 4 different aircraft types that say "I have dealt with this for a long time and can't fix it". Now what?
Bob R
Ed Martin's legacy is smooth. Mine has had a lot of annoying vibes as you describe but virtually all have been removed with lots of cowling interference fixes and plug change. Many pilots forget the alternator can be a wicked source of vibration and it is almost in the same plane as the prop.
The problems I had originally were in that freq range and visible at the wingtip also.
Paul
On 2013-07-25, at 9:54, Charles Brown <browncc1@verizon.net> wrote:
Has anyone definitely flown a vibration-free IO-550 Lancair (or TSIO-550) with *any* propeller? And by vibration-free, I mean it is free of low-frequency 10-20Hz stuff, not the normal noise of flying. What I'm wondering is... is it the 550, making such vibration with *any* propeller?
Charley Brown
Legacy RG 280hr
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Bob Rickard
President, Rickard Consulting Group, Inc.
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