Aircraft Flight Controls Balancing

Flight Controls

• Determining underbalance or overbalance of a control surface can be done in several ways, as illustrated in Figure 7-1.

Balancing Instructions

Aileron

• To determine the balance of an aileron, place it in a balance fixture upside down.
• The aileron is 100% balanced when the flat surface is 3 degrees down from horizontal, measured near the center hinge.
• The specification for the aileron is nominally 100-percent static balanced.
• If an aileron is underbalanced, the unbalance moment can be calculated by multiplying the weight by the distance D.
• The allowable underbalance (tail heavy) is 4 inch-pounds.

Elevator and Rudder

• To determine the balance of an elevator or rudder, place the control surface in a balancing fixture, ensuring free rotation at hinge points.
• The elevator and rudder are 100% balanced when the trailing edge is level with the hinge line.
• The final step in rebalancing is verification that the proper amount of weight was added or removed.

Balance Adjustment

• To adjust the balance, follow the procedure until the surface is balanced according to the specifications.
• If a surface is underbalanced, additional weight must be added forward of the hinge line.
• The required amount of weight can be estimated by dividing the number of inch-pounds out of tolerance by the distance from the hinge line at which the weight will be added.
• If a surface is overbalanced, weight must be removed from the balance weights in the nose of the surface.
• The total adjustment to be made is the unbalance moment plus the minimum amount of underbalance specified.

Learn about the methods to determine underbalance or overbalance of a control surface, specifically the aileron, in aircraft flight controls. Understand the balancing instructions and specifications.