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?
Jim, I was really hoping someone would have had
some input as I am building this exact same configuration. I can not think
of a plausible reason for the engine to be creating this vibration and then
going away after an hour, so I think it must be the prop. Did you get any
input from MT Props?
Craig
Berland