FAA Private Pilot Airplane (PAR)Performance, Weight and BalanceMedium
An airplane is loaded to a total weight of 2,100 lb with a CG of 84.5 in. The pilot adds 20 lb of baggage at an arm of 140.0 in. What is the new CG?
- A86.5 in
- B83.0 in
- C85.0 in
- D84.5 in
Show answer & explanationAnswer & explanation
Correct answer: C. 85.0 in
Original moment = 2,100 × 84.5 = 177,450 lb-in. New baggage moment = 20 × 140.0 = 2,800 lb-in. New total weight = 2,120 lb; new total moment = 180,250 lb-in. New CG = 180,250 ÷ 2,120 = 85.0 in.
Why the other options are wrong
- A. This overstates the aft shift caused by the small baggage addition.
- B. This is too far forward and does not match the added aft moment.
- D. This ignores the added baggage entirely.
Adding Weight and CG Shift
Adding weight aft of the current CG shifts the CG aft; the new CG is found by dividing the new total moment by the new total weight.
- New moment = old moment + (added weight × its arm)
- New weight = old weight + added weight
- New CG = new total moment ÷ new total weight
Memory trick: Add aft weight, CG creeps aft.