My Forney F-1 is placarded against "sustained operation" between about 1900-2150 RPM. I say about because I don't remember the exact numbers but the tach is marked and I pay attention to that marking. When changing power there is a marked increse in vibrations when passing through this zone. Evidently some harmonic sets up , with the attendent danger of fatigue cracking. The engine is a C-90.
Va Couper --- In [email protected], Dan Caliendo <[EMAIL PROTECTED]> wrote: > > Just took delivery of a 415C and made the maiden flight Sunday > evening. It runs smooth under 2,000 and above 2300 rpm; but pretty > rough feeling > inbetween those two rpm's. Is this common with a "standard" prop and > C-90 engine? Is it worth exploring a dynamic prop balance with this > combination? > I know it has new engine mounts, this vibration has been noticed by > previous owner who avoided those rpm's for that reason, and fairly > recent TOH. > Thanks, > Dan C >
