Final answer:
A loss of oil pressure on an aircraft with propeller counterweights will feather the propeller blades to reduce drag. The related Boeing 767 incident was due to a fuel miscalculation, not loss of oil pressure, but it emphasizes the necessity of system checks and understanding.
Step-by-step explanation:
A loss of oil pressure on a twin-engine aircraft fitted with propeller counterweights will typically result in the automatic movement of the propeller blades into the feathered position. Propeller counterweights are designed to move the blades to a position that minimizes drag in the event of an engine or oil pressure failure. Without oil pressure, the counterweights move the blades so that they are more or less aligned with the airflow, reducing drag and making the aircraft easier to glide and control.
In the case of the incident involving the Boeing 767, this design function was not directly applicable as the loss of power was due to a fuel miscalculation and not a loss of oil pressure. However, it does highlight the importance of proper system knowledge and checks, such as ensuring that gauges are read in the correct units of measurement to prevent accidents.