Tail rotor indexing stops the tail rotor from wind milling in winds up to how many knots?

Tail rotor indexing is a crucial safety feature that prevents the tail rotor of the helicopter from wind milling when the aircraft is on the ground in certain wind conditions. Wind milling occurs when the tail rotor spins freely in the direction of the wind, which can lead to instability and control issues.

The correct answer states that tail rotor indexing stops the tail rotor from wind milling in winds up to 60 knots. This capability is vital because it helps maintain a stable and safe environment while the helicopter is stationary on the ground, especially during adverse weather conditions or high winds. By ensuring the tail rotor does not spin freely, it minimizes the risk of unexpected movements of the aircraft that might compromise safety.

The options that reference a lower wind speed, such as 30 or 45 knots, do not adequately reflect the designed capabilities of the tail rotor indexing feature. Choosing 75 knots overstates the protective ability of the indexing, as it is beyond the operational limits established for safety protocols. Hence, the specification of 60 knots aligns with helicopter design standards for effective tail rotor management, ensuring pilots and ground crews can confidently operate the aircraft in various wind conditions.