I have determined that there is some minute induced oscillation at 2500 to 2550 rpm.
++++++++++++++++++++++ My uninformed views Mark: A buddy died in a KR when the spinner parted company - I prefer to take things that spin (and shake) serious. I don't remember what and where, but I have flown an airplane that was placarded against operation in a given rpm range - I presume it was for a similar reason. I believe that it was a bit of good fortune that you had the starter flex-plate acting as a tell-tale, would you have otherwise known? I tend to think that the propeller is a part of whatever conditions are setting up this harmonic resonance - it may move to a different rpm range (or go away) if you changed props. Maybe that is a test you should consider before you "fix" the problem. Even a borrowed prop that is not really suitable for the KR would provide some info. It may be worth the trouble to move the existing prop relative to the hub - maybe 90 degrees (or closest). Another test worth considering - some form of temporary brace (reinforcing) on the flexplate. Maybe this oscillation is restricted to The Vair flexplate (it always looked a bit gangly for its size), but maybe one should assume that this is acting on more than just the flexplate. Even if you cure the symptom by spacing the starter - the resonance will still be present with that engine /prop /spinner combo (in the flexplate at least). Oscillation is high speed flexing - is this introducing fatigue? Consider marking it on your ASI and avoiding that range. (Do not rely on memory). +++++++++++++ Last night I tweaked the flexplate until it was tracking true ++++++++++++++++ How? Regards Steve J Ok - 49 days - enough already.
