Power Settings - New Engine - Fixed Pitch Prop
Hi Everyone - I'd be grateful for a bit of advice:
Our 1992 AA5 has just had a factory remanufactured engine fitted and, weather permitting, I will be conducting the first flight test tomorrow (following a ridiculously thorough preflight...) The engine is a 180hp O-360-A4K and we have a fixed pitch cruise prop.
Lycoming advises the 1st flight to be conducted at 75% power for the 1st hour and at settings between 75% and 65% for the second hour (and generally for the 1st 50 hours to be flown at 75%).
As those familiar with Grummans will know, the Tiger POH does not publish power settings by RPM (we're supposed to get these from Lycoming directly). The Lycoming engine manuals, however, rather unhelpfully assume that you know the manifold pressure setting (our aircraft, similar to most other fixed pitch a/c, does not have a manifold pressure gauge). Therefore, the Lycoming power setting charts are completely useless in this case.
From past experience and other aircraft, I think 75% power is about 2,550 RPM and that 65% is somewhere in the region of 2,400 RPM (at reasonably low altitudes and roughly standard temperatures).
Does anyone else have any experience with this or know the exact figures?
Alternatively, does anyone have access to a better chart from which I can ascertain what RPM I should set to achieve a given percentage power setting at a specific altitude/temperature?
Thanks!