An aircraft with an empty weight of 1,800 pounds and an empty weight CG of +31.5 was altered as follows: 1) two 15-pound seats removed at +72; 2) structural modifications +14 at +76; 3) seat and safety belt 20 pounds at +73.5; 4) radio equipment 30 pounds at +30. What is the new empty weight CG?

An aircraft with an empty weight of 1,800 pounds and an empty weight CG of +31.5 was altered as follows: 1) two 15-pound seats removed at +72; 2) structural modifications +14 at +76; 3) seat and safety belt 20 pounds at +73.5; 4) radio equipment 30 pounds at +30. What is the new empty weight CG?

• A. +31.50
• B. +31.61
• C. +32.65
• D. +32.20

Answer: (B)

CG is the weighted average location of all empty-weight components, found by dividing the total moment by the total weight. Start from the original empty weight and moment: 1,800 lb with a CG of +31.5 in gives a moment of 1,800 × 31.5 = 56,700 in-lb. Apply each change while updating both weight and moment: - Remove 30 lb at +72 in: weight becomes 1,770 lb, moment becomes 56,700 − (30 × 72) = 54,540 in-lb. - Add 14 lb at +76 in: weight becomes 1,784 lb, moment becomes 54,540 + (14 × 76) = 55,604 in-lb. - Add 20 lb at +73.5 in: weight becomes 1,804 lb, moment becomes 55,604 + (20 × 73.5) = 57,074 in-lb. - Add 30 lb at +30 in: weight becomes 1,834 lb, moment becomes 57,074 + (30 × 30) = 57,974 in-lb. Final CG = 57,974 / 1,834 ≈ 31.61 in. Thus the new empty weight CG is about +31.61 inches.

CG is the weighted average location of all empty-weight components, found by dividing the total moment by the total weight. Start from the original empty weight and moment: 1,800 lb with a CG of +31.5 in gives a moment of 1,800 × 31.5 = 56,700 in-lb.

Apply each change while updating both weight and moment:

• Remove 30 lb at +72 in: weight becomes 1,770 lb, moment becomes 56,700 − (30 × 72) = 54,540 in-lb.

• Add 14 lb at +76 in: weight becomes 1,784 lb, moment becomes 54,540 + (14 × 76) = 55,604 in-lb.

• Add 20 lb at +73.5 in: weight becomes 1,804 lb, moment becomes 55,604 + (20 × 73.5) = 57,074 in-lb.

• Add 30 lb at +30 in: weight becomes 1,834 lb, moment becomes 57,074 + (30 × 30) = 57,974 in-lb.

Final CG = 57,974 / 1,834 ≈ 31.61 in.

Thus the new empty weight CG is about +31.61 inches.