TSIO 550 guys and or smart engine guys:
I am having a vibration issue and want to see if
anyone has
ideas on what to look for. Basically, at takeoff and climbout to
around
10,000’, the motor and prop are very smooth and strong. There is no
vibration (prop very recently balanced) and all numbers are normal. As
I
pass above 10k to the low flight levels, a vibration in the motor
starts to
develop, and when I level off and set the engine for cruise (LOP,
18gph, 34
MAP, 2500 RPM) the vibration is at its worst. It’s almost like the
prop is out of balance, which is why I had the prop balanced at 2500
rpm.
Speeds are good and all engine numbers are normal, no changes. This
will
remain for an hour or 2, then the motor seems to magically smooth
itself out. On
descent and landing, motor seems smooth and all numbers are normal.
Very
recently, on a 4.5 hour flight, about 3.5 to 4 hours in the vibration
slowly
came back. I don’t know what to blame, and my motor mechanic is
looking at me funny. I should note that at no time do I think the
vibration is horrible or unsafe, just annoying. I can feel it in the
stick and see it in the panel when its happening.
Things I have ruled out:
Balance
of the prop
Dirty
plugs or fuel injectors (new plugs and cleaned injectors)
Speed
effect (increase or decrease speed has no effect)
Fuel
issues
Flight
control flutter or anything like that
Things that have been suggested:
A
bad valve in a cylinder that doesn’t show until you get to altitude,
Or
bad compression in a cylinder that comes and goes (all cyl’s were comp
tested a month ago though)
Turbo
controller not scheduling properly as you climb
Fuel
injection system malf?
I’m hoping one of you has had this problem and
can
point me and the mechanic to the possible culprit. Appreciate any
comments
Bob Rickard
IV-P