Which surface does not have manually operated trim tabs installed?

The correct answer highlights that the right aileron does not have manually operated trim tabs installed. In aviation, ailerons are crucial for roll control, and they can be equipped with trim tabs to help alleviate the need for constant pilot pressure on the controls to maintain straight and level flight or to counteract any imbalance.

In many aircraft designs, including those similar to the T-54A, only one of the ailerons might be fitted with trim tabs for operational efficiency or to reduce pilot workload. In this case, the aircraft features a manually operated trim tab on the left aileron, which assists in balance and control during flight.

Most aircraft utilize trim systems on vertical and horizontal stabilizers as well, allowing for effective management of pitch and yaw stability. The vertical stabilizer often has a rudder trim tab for side-to-side adjustments while the horizontal stabilizer may have elevator trim tabs for pitch adjustments. The absence of a manually operated trim tab on the right aileron is a specification unique to the aircraft's design aimed at simplifying controls while still maintaining effective flight operations with the available trim systems.