At what temperature do the propeller blades heat for 90 seconds before turning off for 90 seconds?

The correct temperature threshold for heating the propeller blades for 90 seconds before turning them off for another 90 seconds is indeed less than -16 degrees. This procedure is typically implemented as part of frost or ice prevention measures on aircraft. When temperatures drop to levels below -16 degrees Celsius, the risk of ice accumulation on the propeller blades increases, making it essential to heat them periodically to ensure safe operation and optimum performance.

In this context, the heating cycle is critical as it helps to maintain the blades’ effectiveness and prevent ice from negatively impacting aerodynamic performance. This specific operating procedure aligns with safety protocols and operational guidelines in cold weather conditions, ensuring that pilots can manage potential hazards associated with ice on the propellers effectively.