CPAER Canada Commercial Pilot Practice Exam 2026 – Complete Prep Guide

In a Constant Speed Propeller equipped with counterweights, when oil pressure is lost, the blades will move to the Full Coarse or Feathered Position. This is an important safety feature designed to protect the aircraft.

In normal operation, oil pressure is used to adjust the propeller blade angle for optimum performance. When there is a loss of oil pressure, the mechanism that typically maintains the blade angle is compromised. The counterweights act as a fail-safe system; without the oil pressure to keep the blades in a fine position (which allows for more power and thrust), the counterweights pull the blades to a coarse or feathered position.

This feathered position reduces drag significantly, especially in the event of an engine failure, as it aligns the blades with the airstream. Hence, this minimizes the impact on flight performance and allows the pilot to manage the situation more effectively during an emergency.

Understanding the interaction between oil pressure and counterweights in a Constant Speed Propeller is crucial for pilots, as it affects how the aircraft responds in critical situations.