If RPM is low and manifold pressure is high, what initial corrective action should be taken?

When the RPM (Revolutions Per Minute) is low while the manifold pressure is high, the initial corrective action should focus on reducing the load on the rotor system to help restore the proper operating parameters. Lowering the collective pitch decreases the angle of the rotor blades, which reduces lift and subsequently lowers the load on the engine. This action allows the engine to spool up the rotor's RPM more effectively, addressing the low RPM condition while still respecting the high manifold pressure.

By taking this action, the pilot effectively allows the engine to operate within a more favorable range, increasing the chances of the rotor reaching its optimal RPM. This is particularly important in a helicopter, where maintaining adequate rotor speed is critical for safe flight operations. Lowering the collective pitch is a common and effective method for managing engine performance issues relating to RPM fluctuations in this scenario.