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Hi All:
Just wondering if anyone has an idea on which way to go to start trouble shooting this problem.
Here are the particulars:
I have a Legacy with about 120 hrs on it. Performance Engines IO-550 / Hartzell Prop / Mags.
It has been running exceptionally well, very smooth until just yesterday when I first noticed a sort of nondescript rumble/vibration after a long descent at relatively high speed, from 17,500'.
As we slowed to enter the pattern for landing it cleared up and everything seemed normal. I went out and flew today to see if it was just an anomaly......apparently it was NOT.
* A download of all the engine parameters was normal...... nothing out of the ordinary.
* Engine run-up and full power run were all normal/smooth.
* Takeoff and initial climb out were all normal with no vibration UNTIL we accelerated through approximately 165kts.
* At 165kts and greater, on three successive flights, we felt a distinct cyclical type vibration setting up. It's a bit hard to describe in words but it does NOT seem to be a steady vibration (like a gear door) but seems to feel almost like a prop out of balance.
* Without touching the power or prop we can make the vibration go away by raising the nose and slowing < 165kts.
* When we do get the vibration > 165kts..... you can mitigate it somewhat by increasing prop RPM. The vibration is still there but not has bad.
* The prop is NOT surging in any way, RPM's are rock steady and remain where they are set.
* The issue is serious enough, in my mind, that I am DRIVING tomorrow from San Diego to Las Vegas.......and I HATE driving;)))
So in summary, it seems this vibration just happened somewhat spontaneously (ie. not progressively worsened over time) and although were not ruling anything out, it seems to be Engine/Prop/Speed related.
We would GREATLY appreciate any ideas, comments, suggestions.... we are kind of at a loss as to which way to head in troubleshooting/fixing this problem.
Best regards,
Erik Larson
asw20747@aol.com
(619) 301-7475
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