In CG weighing, the arms extend parallel to which feature of the aircraft?

• A. The wing
• B. The centerline
• C. The tail
• D. The datum line

Answer: (B)

Arms in CG weighing are the lever distances used to compute moments, and they run along the aircraft’s length. That means they are parallel to the longitudinal axis, or centerline, from the chosen reference datum to where the weight acts. This orientation makes sense because shifting weight forward or aft changes the balance along the fuselage, and moments are calculated as weight times arm along that same longitudinal direction. The wing region or the tail aren’t the directions used for the lever arm, and the datum line serves as the reference point for zero moment rather than defining the arm’s direction. So the arms extend parallel to the centerline.