A&P Practical Weight and Balance: A Worked Problem
An A&P practical weight and balance exercise asks you to work with the numbers, units, and aircraft data. This O&P study example uses invented scale readings and arms to demonstrate the FAA handbook method. The arithmetic is an illustration, not data for a real aircraft or a prediction of your assigned project.
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Which weight-and-balance tasks are in the O&P standard?
The ACS skill list includes performing weight-and-balance calculations, computing forward and aft loaded CG limits, computing empty weight and empty-weight CG, and identifying tare items. The FAA sample’s General project uses the loaded-CG-limit task (AM.I.C.S6). Read the assigned task: an empty-weight calculation and a loaded-limit calculation are different exercises.
FAA-S-ACS-1, p. 4 · FAA sample O&P, PDF p. 6
For real work, follow the manufacturer’s data or other applicable approved data and the DME’s instructions. The study examples below do not establish aircraft-specific limits or replace the assigned procedure. The Weight & Balance Handbook expressly gives manufacturer-specific information precedence over conflicting handbook information.
FAA-S-ACS-1, p. A-3 · FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, p. 16 · FAA-H-8083-1B, p. iii
What are the givens in this practice problem?
For this illustrative empty weight CG calculation, assume the training aircraft is in the empty-weight configuration required by its manufacturer, is properly levelled, and has the following invented readings. Arms are in inches from one common imaginary datum. The nose weighing point is forward of that datum; both main points are aft.
| Weighing point | Scale reading (lb) | Tare (lb) | Net weight (lb) | Arm (in) |
|---|---|---|---|---|
| Nose | 302 | 2 | 300 | -20 |
| Left main | 452 | 2 | 450 | +50 |
| Right main | 453 | 3 | 450 | +50 |
| Total | 1,207 | 7 | 1,200 | — |
The handbook method subtracts tare from the scale reading to obtain the net weight at each point. It then multiplies each net weight by its arm to obtain its moment. Keep the sign of the arm in the multiplication.
FAA-H-8083-1B, p. 3-6 · FAA-H-8083-1B, p. 2-2
How do you calculate the moments and empty-weight CG?
| Weighing point | Illustrative calculation | Moment (lb-in) |
|---|---|---|
| Nose | 300 × (-20) | -6,000 |
| Left main | 450 × 50 | +22,500 |
| Right main | 450 × 50 | +22,500 |
| Total | -6,000 + 22,500 + 22,500 | +39,000 |
The FAA method divides total moment by total weight. For the invented data above, CG = 39,000 lb-in ÷ 1,200 lb = +32.5 in. The illustrated empty weight is 1,200 lb, with its CG 32.5 inches aft of the chosen datum. The positive result follows from the signed moments in this example.
FAA-H-8083-1B, p. 2-2 · FAA-H-8083-1B, p. 3-6
For a study cross-check, add the scale readings and tares separately: 1,207 - 7 = 1,200 lb. Then repeat the moment sum before dividing. This is our checking routine, not an FAA step.
Does 32.5 inches mean the aircraft is within limits?
No. A CG result must be compared with the applicable aircraft data. For an empty-weight CG, that means the empty-weight CG range on the aircraft’s TCDS, when one is listed. If the result falls outside that range, or the TCDS lists the range as “None,” the handbook calls for an adverse-loading check of the forward and aft limits. No range was supplied in this invented problem, so the arithmetic alone establishes no within-limit conclusion.
FAA-H-8083-1B, p. 2-6 · FAA-H-8083-1B, p. 1-3 · FAA-H-8083-1B, p. 7-6 · FAA-H-8083-1B, p. iii
On your worksheet, identify the datum, the weighing configuration, the net weights, and the limit source before drawing a conclusion. If the assigned project concerns loaded forward and aft limits, use the project information and aircraft records for that task instead of substituting this empty-weight example.
What should you rehearse next?
Redo the calculation from a blank sheet, then explain why tare was removed and why the nose moment is negative. For a separate spoken review, use the weight-and-balance oral questions. Keep the calculation practice tied to the assigned task and its references.
Frequently asked questions
Is this the exact weight-and-balance problem I will receive at the O&P?
No. The values here are invented for study, and the ACS does not disclose the selected tasks before testing.
Should I use the gross scale reading to calculate the aircraft moment?
No. In the handbook method shown here, subtract tare at the weighing point before multiplying net weight by its arm.
Why is the nose moment negative in this example?
Because the illustrated nose arm is -20 inches relative to the chosen datum, so 300 lb multiplied by that arm gives -6,000 lb-in. This sign comes from the example’s givens, not a rule that every nosewheel arm is negative.
Does a correctly calculated CG prove that the aircraft is airworthy?
No. The calculation still needs the applicable aircraft configuration and limits; this example provides no approved limit range or real-aircraft release determination.
Rehearse the spoken answer with DMEReady
DMEReady is an AI voice examiner for the A&P oral in your phone or computer browser. You answer out loud, and it asks follow-up questions the way a DME would. An oral can also be built from the ACS codes on your Airman Knowledge Test Report (AKTR). It rehearses the oral; it does not train hands-on practical skills. After a session, the report shows what you covered, what you missed, what a complete answer includes, and where to read in the FAA handbooks. You can save it as a PDF study sheet or share a result image that never shows your answers or name. The first drill is free, with no sign-up. DMEReady is an AI examiner, not a human DME. It is independent and is not affiliated with or endorsed by the FAA; it does not predict or guarantee results.
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Related guides
Sources
FAA sources checked October 18, 2026.
- FAA-S-ACS-1
- FAA sample oral and practical test
- FAA Order 8900.1, Vol. 5, Ch. 5, Sec. 11, Administer an Oral and a Practical Test (CHG 929, 9/17/2024)
- FAA-H-8083-1B, Weight & Balance Handbook (with October 2025 addendum)
About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides
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