Several reasons for a restricted RPM, due to harmonic
vibration...some say not to have prolonged operation in
certain RPM ranges, some have a red range in the green arc.
I think Lycomng has a FAQ on their engines.


"Roy Smith" wrote in message
...
| john smith wrote:
| Jack Allison's discussion of the Hartzell AD for his
Arrow has gotten me
| to thinking.
| What aircraft do you fly/have you flown/do you have
first hand knowledge
| of which have a red zone somewhere in the green arc of
the tachometer?
|
| My club used to have an Arrow-II which had a red arc from
(IIRC 2150 - 2300
| RPM). Green above and below that. The POH listed only
two allowable
| cruise RPMs: 2100 or 2400, nothing in between.
|
| I may be off a little on the actual numeric values.