Weight and Balance Fundamentals

Weight and balance rests on a few terms. The empty weight is the airplane with operating fluids but no people, bags, or usable fuel. The useful load is what is left before hitting maximum gross weight — the pilot, passengers, fuel, and baggage. Where each item sits is measured by its arm, the distance in inches from the reference datum, and the product of weight and arm is the moment. To work a loading problem you list every item with its weight and arm, multiply to get each moment, add up the weights, add up the moments, and divide total moment by total weight to find the center of gravity. A loading is legal only if the total weight is at or below the maximum AND the CG falls between the forward and aft limits. Both tests must pass; an airplane can be light but still nose- or tail-heavy. Because fuel burns off during flight and shifts the CG, a loading that is legal at takeoff must remain legal at landing. The exam works this as arithmetic on Testing Supplement loading graphs and tables: drill the full moment computation, plotting a load on the CG envelope, the effect of moving or adding baggage and of fuel burn on CG position, and how much weight change brings an over-gross loading back to maximum gross. Practice with the FAA loading-graph figures until reading moments off the chart is routine — the questions are calculations, not definitions.