PPL » Aircraft Tech Knowledge (A) » Weight and Loading
12.108 Weight and Loading
12.108.2 Given a basic aircraft load sheet/data, demonstrate the ability to:
(a) calculate the C of G position;
To calculate the centre of gravity (C of G) position, determine the moment of each item, then divide the total moment by the total weight.
Step 1 — Calculate the Moment of Each Item
Weight × Arm = Moment
Where:
- Weight = weight of the item
- Arm = distance from datum
- Moment = turning effect
Step 2 — Total the Weights and Total the Moments
Total Weight = Add up all Weights
Total Moment = Add up all Moments
Step 3 — Calculate C of G Position
This gives the C of G arm (distance from datum).
Example
| Item | Weight (lb) | Arm (in) | Moment (lb-in) |
|---|---|---|---|
| Empty aircraft | 1500 | 40 | 60,000 |
| Pilot | 170 | 37 | 6,290 |
| Passenger | 150 | 73 | 10,950 |
| Fuel | 200 | 48 | 9,600 |
| Baggage | 50 | 95 | 4,750 |
Totals:
Total Weight = 2070 lb
Total Moment = 91,590 lb
Calculate C of G:
C of G = 44.2 in
Answer: C of G = 44.2 inches aft of datum
Final Check
Compare the calculated C of G with the aircraft’s approved C of G limits to confirm it is within range.
Summary:
Weight × Arm = Moment
Total Moment ÷ Total Weight = C of G Position
(b) use a typical loading graph to determine C of G position;
A loading graph provides a quick method of determining the aircraft’s centre of gravity position without manually calculating every moment.