When increasing power in a constant speed propeller aircraft, which should you always increase first to prevent undue engine stress?

In a constant speed propeller aircraft, increasing RPM first is crucial to ensure that the propeller can efficiently convert the engine's power output into thrust without causing stress on the engine. When the RPM is increased before making any adjustments to manifold pressure, the propeller can maintain an appropriate blade angle, allowing it to manage the increased power characteristics effectively.

If the manifold pressure were to be increased without proper RPM adjustment, it could lead to excessive load on the engine that is not yet matched by sufficient thrust production. This mismatch can cause engine stress, leading to potential damage or reduced longevity. Therefore, starting with an RPM increase allows the propeller to adjust to the engine's power output in a controlled manner, ensuring smooth and efficient operation.

In contrast, increasing manifold pressure without prior RPM adjustments could risk overloading the engine, resulting in potential operational issues. Earlier adjustments to fuel flow or airspeed are also relevant, but they should follow the adjustment of RPM to maintain efficient engine performance and prevent undue stress. Thus, prioritizing RPM when increasing power is a best practice for engine health and operational efficiency in constant speed propeller aircraft.