I say interesting Vibration problem because it goes away, after 30 min. it is almost gone and after 1 hr. it is completely smooth. I have a LlVP with a 550E and 4 blade MT prop. I had the engine completely overhauled 15 hrs ago and the prop sat on a pale for almost 4 months. The prop had new seals and grease installed over 200 hrs ago.

The problem is just after take off the panel glareshield vibrates up and down about 1 in. The engine installer balanced the prop before a test pilot flew it. He reported a vibration so I had the prop rebalanced after 5 hrs. Every take off since has done this and with RPM changes, power changes it is consistent. The only change in vibration is Time. It is perfectly smooth after 1 hr.

 

Possible causes;

Maybe a stuck valve or lifter not adjusting?? Not likely.

 

The MT prop still leaked grease after the seal replacement 200 hrs ago, however, a lot less then before. So one thought is that the remaining grease rests on one side of the hub when parked for 2 weeks and since it is in the cold end of the crankshaft, is heavy grease, and it doesn't get the warm oil for some time, it may take that long for it to even out around the HUB, causing out of balance?

 

Another is I'm told that the MT prop blades have a bearing preload that is set when being installed in the Hub, and that preload needs to be set the same for all 4 blades. This is done by hand and feel, I'm told. If one is loaded too much it lags in the Tracking and will cause this vibration which corrects itself after hub warms or given some time at the same setting. ???? Why would this start now after being off the engine and then reinstalled?

 

These are my three possibilities. I would love any thoughts and or experiences.