Final answer:
The function of a propeller overspeed governor in the event of lost oil pressure is to maintain a safe propeller speed to prevent overspeed.
Step-by-step explanation:
The function of a propeller overspeed governor in the event of lost oil pressure in the propeller system is to maintain a safe propeller speed to prevent overspeed. When there is no oil pressure, the governor will react by decreasing the blade angle of the propeller to limit its rotational speed. It does this by changing the pitch of the blades or using centrifugal force.