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Ballast placement relative to the affected limit

Aviation Mechanic General (AMG) practice question 20 of 25 on Weight and Balance. ACS element AM.I.C.K8 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONTo correct an out-of-limits CG with the least amount of ballast, the ballast should be placed

  1. Aas far as possible from the affected CG limit
  2. Bas close as possible to the datum
  3. Cat the aircraft's center of gravity so no additional moment is produced
Show the answer and explanation

Correct answer: A. as far as possible from the affected CG limit

  • A — correct The handbook states ballast is always placed as far away from the affected limit as possible, because a longer arm means less weight is needed.
  • B — incorrect The datum is only a measurement reference; the distance that matters is between the ballast and the limit being corrected.
  • C — incorrect Ballast works by producing a moment; placing it at the CG would add weight without shifting the balance.

BACKGROUND

Ballast is used to attain the desired CG when the CG is not within limits or not where the operator wants it. It is usually located as far aft or as far forward as possible to bring the CG within limits while using a minimum amount of weight. In the handbook's example, 47 lb of ballast in a forward baggage compartment corrected an aft CG, and the text notes that if the ballast could have been bolted farther forward at the engine firewall, less ballast would have been needed. The amount needed is found from the loaded weight, the distance the CG is out of limits, and the distance between the ballast location and the affected limit.

STUDY TIP

Longer arm, less ballast: always look for the location farthest from the limit being exceeded.

KEY POINTS

  • Ballast is placed as far as possible from the affected limit.
  • A longer arm reduces the ballast weight needed.
  • Ballast weight depends on loaded weight, distance out of limits, and ballast arm.

SOURCES

  • FAA-H-8083-30B ch06 "Use of Ballast"
  • FAA-H-8083-30B ch06 "Temporary Ballast Formula"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.