Koamill writes:
It seems that in both model Nr needs to be drooped to get better performances... And that, I think, is the main question, what improve in performance you get drooping Nr.
I think there is not a simple answer to your question, because I believe that the optimum Nr for OEI climb is a function of Weight, altitude, temperature, and airspeed. I’m not aware of any Flight Manual performance charts that show OEI ROC as a function of Nr (albeit I haven’t seen the Flight Manuals for all the different models). If a manufacturer determines that reducing the normal AEO Nr produces better OEI climb performance overall, then the OEI climb performance charts will be published for the reduced Nr. When flying Category A (Performance Class 1) procedures, the pilot is not at liberty to deviate from the Certified procedure. Presumably the manufacturer has already experimented with different Nr’s and published Flight Manual performance data and OEI emergency procedures accordingly.