This is a reminder that the normal engine speed operating limit (top of green arc, representing ~75% BHP) changes with altitude.
See also POH:
- Section 4: ENROUTE CLIMB and CRUISE
- Section 5: CRUISE PERFORMANCE / RANGE / ENDURANCE
– 2,500 RPM between sea level and 5,000′
– 2,600 RPM from 5,000′ – 10,000′
– 2,700 RPM above 10,000′