In flight, which statement best describes feathering behavior when oil pressure is removed from a McCauley propeller?

In flight, which statement best describes feathering behavior when oil pressure is removed from a McCauley propeller?

• A. Aerodynamic forces keep the propeller rotating fast enough that centrifugal force holds the blades unlatched so they can move to the feather position when oil pressure is removed.
• B. The blades immediately feather when oil pressure is removed.
• C. The blades move to feather due to spring pressure.
• D. The governor re-engages to hold speed.

Answer: (A)

Feathering happens when oil pressure is removed, and the propeller blades are driven to a high pitch to minimize drag in an engine-out condition. In a McCauley prop, the turning blades create centrifugal force that helps keep the pitch mechanism from locking (unlatched). With the oil pressure gone, there’s nothing forcing the blades to stay in their previous low-pitch setting, so the combination of centrifugal force and the prop’s internal weights and springs allows the blades to move to the feather position. The result is rapid feathering driven by the loss of oil pressure, aided by the fact that the rotating prop establishes the conditions for the mechanism to respond once pressure is gone.

Feathering happens when oil pressure is removed, and the propeller blades are driven to a high pitch to minimize drag in an engine-out condition. In a McCauley prop, the turning blades create centrifugal force that helps keep the pitch mechanism from locking (unlatched). With the oil pressure gone, there’s nothing forcing the blades to stay in their previous low-pitch setting, so the combination of centrifugal force and the prop’s internal weights and springs allows the blades to move to the feather position. The result is rapid feathering driven by the loss of oil pressure, aided by the fact that the rotating prop establishes the conditions for the mechanism to respond once pressure is gone.