The basic aircraft design assumes that lateral symmetry
exists. For each item of weight added to the left of the
centerline of the aircraft (also known as buttock line
zero, or BL-0), there is generally an equal weight at a
corresponding location on the right.
The lateral balance can be upset by uneven fuel loading
or burnoff. The position of the lateral CG is not normally
computed for an airplane, but the pilot must be aware
of the adverse effects that will result from a laterally
unbalanced condition. [Figure 1-4] This is corrected by
using the aileron trim tab until enough fuel has been used
from the tank on the heavy side to balance the airplane.
The deflected trim tab deflects the aileron to produce
additional lift on the heavy side, but it also produces
additional drag, and the airplane flies inefficiently